CN107949987B

CN107949987B - Filter superposition for carrier aggregation

Info

Publication number: CN107949987B
Application number: CN201580082882.3A
Authority: CN
Inventors: 德罗尔·雷格夫; 希米·西隆; 埃兹里·多伦; 特所迪克·根纳季; 张军平; 胡根根; 梁栋; 苗延楠
Original assignee: Huawei Technologies Co Ltd
Current assignee: Honor Device Co Ltd
Priority date: 2015-09-07
Filing date: 2015-09-07
Publication date: 2020-03-20
Anticipated expiration: 2035-09-07
Also published as: WO2017041814A1; CN107949987A

Abstract

A receiver system for generating a filtered signal comprises a frequency converter and a filtering unit. The frequency converter includes a local oscillator. The frequency converter receives a radio frequency signal within a first frequency bandwidth and shifts the radio frequency signal to a second frequency bandwidth. The filtering unit filters the displacement signal by applying a band-pass filter (BPF). The derived BPF is generated by superimposing at least one BPF and at least one band-stop filter (BSF).

Description

Filter superposition for carrier aggregation

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a filter superposition technique for carrier aggregation.

Background

The present invention, in some embodiments thereof, relates to carrier aggregation signal processing and, more particularly, but not exclusively, to filtering carrier aggregation signals.

Carrier Aggregation (CA) in wireless communications will become a key method to increase bandwidth and data rate and to utilize the best segmented spectrum available in wireless communications (e.g., LTE, Wi-Fi).

Modern wireless communication standards support the following types of CA:

(i) continuous CA in band;

(ii) intra-band non-consecutive (NC) CA;

(iii) intercand CA.

The aggregated component carriers may have different bandwidths, and each aggregated component carrier may transmit at a different power level. Fig. 1 shows three types of CA.

Non-contiguous carrier aggregation (NC CA) presents many challenges for several reasons:

(i) the aggregate carrier has a wide total processing Bandwidth (BW) that may span the entire frequency band where interfering signals are desired between carriers.

(ii) Data rate and vector magnitude Error (EVM) requirements in LTE and 802.11ac using high order QAM are already stringent and the effects of CA further increase the demand for higher EVM performance.

(iii) EVM requirements for CA-capable transceivers seek to exploit the performance of each component carrier with minimal mutual interference reduction.

(iv) CA in receive mode must consider in-band and out-of-band blockers and carriers with different receive bandwidths and amplitudes.

Fig. 2 illustrates the difficulties of wide processing bandwidth, mutual interference and in-band blockers.

The CA includes a multi-terminal Local Oscillator (LO) and a single-terminal LO receiver scheme. The advantages of a single-ended LO implementation are: only one LO synthesizer circuit is needed without LO pulling and/or coupling risks.

Some prior art processing methods for aggregating different receiver channels span the entire frequency band, thereby processing multiple carriers simultaneously, as shown in fig. 3. The down conversion unit may employ one of the conventional topologies:

(1) superheterodyne type;

(2) low Intermediate Frequency (IF); or

(3) Direct conversion using in-phase and quadrature (IQ) channels.

Broadband direct conversion has several disadvantages. The wideband filter cannot suppress the inband blocker (as shown in fig. 4), which may degrade signal purity and/or saturate baseband (BB) circuitry and analog to digital converter (ADC). A wideband ADC with a high dynamic range and a large number of received bits is required.

An article written by Run Chen and Hashemi h. at the university of southern california in los angeles, california, usa with a Reconfigurable blocker-resilient receiver (Reconfigurable block-resilient receiver with current channel-band carrier aggregation) for synchronous dual-frequency carrier aggregation proposes a technique to symmetrically shift the filter center frequency ± Δ f to produce two low selectivity C-filters (as shown in fig. 5).

A second article written by Run Chen and Hashemi h, university of southern california at los angeles, california, usa, "Reconfigurable SDR Receiver with Enhanced Front-end Frequency selectivity suitable for Intra-Band and Inter-Band Carrier Aggregation (Reconfigurable SDR Receiver with Enhanced Front-end Frequency selectivity for Intra-Band and Inter-Band Carrier Aggregation)" presents a graphical technique for aggregating three component carriers to different Frequency shifts. The second order RC filter frequency shifts to three different positive and negative frequency shifts as shown in fig. 6A. The band-pass filter (BPF) selectivity is enhanced to the second order. A quadratic notch filter is used at DC. In addition, the impedance of the frequency shift filter is inverted using a known technique and the BPFs are aggregated in the current domain, as shown in fig. 6B.

In the above two schemes, the filter is narrow-band and is not wide enough for advanced wireless communication technologies such as CA. The frequency shift Δ f is limited in frequency and increasing Δ f increases power consumption. In addition, low rejection/selectivity filters (e.g., second order bandpass filters) are not suitable for strong blockers inside and outside the aggregate channel. Thus, while prior art methods are directed to blocker suppression, effective and stringent blocker suppression is insufficient.

Other background art includes carrier aggregation for LTE-advanced written by Chester: terminal Design challenge (Carrier rAggregation for LTE-Advanced: Design changes of Terminals) ", Sungchung park, university of Konkuk and Lars

Ericsson research, longde, sweden.

Disclosure of Invention

Direct conversion receivers typically employ a Low Pass Filter (LPF) or a complex BPF centered at 0hz (dc). The bandwidth of such filters is typically adjustable to receive the various BW component carriers and block potential blockers in the vicinity. If two non-contiguous equal BW component carriers are to be aggregated, a highly selective band pass filter should be utilized to suppress the intermediate potential blockers.

To obtain a highly selective band pass filter, embodiments herein superimpose two or more filters to generate a derived filter with a desired transfer function. The filters may be stacked in parallel and/or series depending on the receiver domain requirements (e.g., impedance matching, high impedance, low impedance, etc.). Some embodiments utilize impedance transformers to create the BPF or BSF through impedance inversion techniques.

According to a first aspect of some embodiments of the present invention, there is provided a receiver system for generating a filtered signal. The receiver system includes a frequency converter including a Local Oscillator (LO) and a filtering unit. The frequency converter receives a radio frequency signal within a first frequency bandwidth and shifts the radio frequency signal to a second frequency bandwidth. The filtering unit filters the radio frequency signal within the second frequency bandwidth by applying a band-pass filter (BPF) to generate a filtered signal, wherein the derived BPF is generated by superimposing at least one BPF and at least one band-stop filter (BSF).

In a first possible implementation form of the system according to the first aspect, the receiver system comprises a controller for adjusting the bandwidth of at least one BPF and/or at least one BSF, thereby changing the center frequency and/or the bandwidth of the derived BPF.

In a second possible implementation form of the system according to the first aspect, the at least one BPF and the at least one BSF are centered around a DC frequency, and the derived BPF is displaced around a target positive and negative frequency with respect to the DC frequency.

In a third possible implementation form of the system according to the first aspect, the at least one BPF and the at least one BSF are integrated circuit components in an integrated circuit, wherein the integrated circuit implements a Carrier Aggregation (CA) receiver filter of the receiver system.

In a fourth possible implementation form of the system according to the first aspect, the at least one BPF comprises a plurality of composite BPFs, and the at least one BSF is implemented by transforming an impedance of at least one of the derived BPFs.

In a fifth possible implementation form of the system according to the first aspect, the receiver system is implemented as an integrated circuit component in voltage mode.

In a sixth possible implementation form of the system according to the first aspect, the at least one BSF and the at least one BPF are connected in parallel. In a second possible implementation form of the system according to the sixth possible implementation form of the first aspect, the at least one BPF is wider than the at least one BSF. In a third possible implementation form of the system according to the sixth possible implementation form of the first aspect, the at least one BSF and the at least one BPF generate two symmetrically displaced composite BPFs.

In a seventh possible implementation form of the system according to the first aspect, the receiver system comprises at least one impedance transformer for transforming the derived BPF from a voltage mode to a current mode.

In an eighth possible implementation form of the system according to the first aspect, the at least one BPF and the at least one BSF are defined according to a transfer function in an impedance domain, such that the derived BPF defines a configurable transfer function in the impedance domain.

In a ninth possible implementation form of the system according to the first aspect, the filter signal encodes component carriers defined for Carrier Aggregation (CA) and having a narrower bandwidth than the first frequency bandwidth.

In a tenth possible implementation form of the system according to the first aspect, the at least one BPF comprises a first composite BPF covering the second frequency bandwidth and a second composite BPF covering a frequency bandwidth narrower than the second frequency bandwidth.

In an eleventh possible implementation form of the system according to the first aspect, the at least one BPF and the at least one BSF are integrated circuit components, the receiver system comprising at least one impedance inverter connected in series to the second composite BPF and the at least one BSF.

In a twelfth possible implementation form of the system according to the first aspect, the at least one BSF and the at least one BPF are connected to each other in a serial manner. In a second possible implementation form of the system according to the twelfth possible implementation form of the first aspect, the at least one BPF and the at least one BSF are impedance matched.

According to a second aspect of some embodiments of the present invention, there is provided a method for receiving data transmitted by Radio Frequency (RF) signal combining. The method comprises the following steps:

(i) receiving a radio frequency signal within a frequency bandwidth;

(ii) superimposing at least one band-pass filter (BPF) and band-stop filter (BSF) covering the frequency bandwidth to generate a derived BPF;

(iii) applying the derived BPF to the radio frequency signal to generate a plurality of filtered signals.

In a first possible implementation form of the method according to the second aspect, the plurality of radio frequency signals are received by a frequency converter comprising a single-ended Local Oscillator (LO).

Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not necessarily limiting.

Drawings

By way of example only, some embodiments of the invention are described herein in connection with the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the embodiments of the present invention. Thus, it will be apparent to one skilled in the art from the description of the figures how embodiments of the invention may be practiced.

In the drawings:

fig. 1 illustrates three carrier aggregation techniques;

fig. 2 illustrates the difficulty of wideband CA signal processing;

FIG. 3 is a simplified block diagram of a wideband CA signal processing system;

fig. 4 shows the result of the broadband filtering of the CA signal;

FIGS. 5-6B are simplified transfer functions of a prior art aggregation filter;

FIG. 7 is a simplified diagram of a superposition of two filters according to an embodiment of the present invention;

fig. 8A-8B are simplified block diagrams of a receiver system for generating a plurality of filtered signals according to first and second embodiments of the present invention.

Fig. 9A-9C are simplified diagrams illustrating derived BPF adjustments;

FIG. 10 is a simplified block diagram of BSF formation from BPF using impedance inversion;

FIG. 11 is a simplified block diagram of a direct conversion system according to some embodiments of the present invention;

FIG. 12 is a simplified block diagram of an impedance matched derived BPF according to an exemplary embodiment of the present invention;

FIG. 13A is a simplified block diagram of a high-passband impedance derived BPF in accordance with an exemplary embodiment of the present invention;

fig. 13B is a simplified block diagram of a receiver system including a derived high-passband impedance BPF in accordance with an exemplary embodiment of the present invention;

FIG. 13C is a simplified block diagram of a derived high-passband impedance BPF in accordance with an exemplary embodiment of the present invention;

FIG. 14 is a simplified block diagram of a derived low pass-band impedance BPF in accordance with an exemplary embodiment of the present invention;

figure 15 illustrates the superposition of three filters to produce a derived passband filter transfer function in accordance with an embodiment of the present invention.

FIG. 16 is a simplified block diagram of a derived high-passband impedance BPF according to an exemplary embodiment of the present invention;

FIG. 17 is a simplified flow diagram of a method for receiving data transmitted via RF signal combining in accordance with an embodiment of the present invention;

fig. 18 is a graph illustrating simulation results of blocker channel suppression obtained by a multi-step derivative filter.

Fig. 19 shows the received signal constellation obtained by a multi-order derivative filter.

Detailed Description

Wireless communication systems and chips may have more than one baseband (BB) channel and use complex (IQ) bandpass filtering at baseband. Multiple baseband channels and IQ filters are particularly prevalent in receivers for CA.

Embodiments presented herein employ a DC-centered, highly selective BPF and a band-stop filter (BSF) that are superimposed to create a broadband, highly selective, scalable BPF of targeted positive and negative frequencies. Some embodiments are implemented by impedance inversion, so that high and low impedance baseband filters operate together. Direct conversion CA is supported, as detailed herein.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and/or methods set forth in the following description and/or illustrated in the drawings and/or examples. The invention is capable of other embodiments or of being practiced or carried out in various ways.

The present invention may be a system, a method and/or a computer program product. The computer program product may include one (or more) computer-readable storage medium(s) having computer-readable program instructions stored thereon for causing a processor to perform various aspects of the present invention.

The computer readable storage medium may be a tangible device that can retain and store the instructions for use by the instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic memory device, a magnetic memory device, an optical memory device, an electromagnetic memory device, a semiconductor memory device, or any suitable combination of the foregoing.

The computer-readable program instructions described herein may be downloaded from a computer-readable storage medium to a corresponding computing/processing device, or to an external computer or external storage device via a network, such as the internet, a local area network, a wide area network, and/or a wireless network.

The computer-readable program instructions may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the internet using an internet service provider). In some embodiments, the electronic circuitry comprises programmable logic circuitry, a field-programmable gate array (FPGA), or a Programmable Logic Array (PLA), and the computer-readable program instructions are executable by state information of the computer-readable program instructions to personalize the electronic circuitry to perform aspects of the present invention.

Aspects of the present invention are described below with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer-readable program instructions.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

Embodiments herein provide for superimposing baseband filters to obtain a bandpass filter with a scalable center frequency and bandwidth shifted from DC.

Assuming a filter transfer function H₁(S)，H₂(S)……H_n(S) in which H₁(S) is one at DC (for straight)Receiver-to-receiver) as a center, tunable BW BPF, which can be used for receiving band and H₁(S) as wide as the component carrier. In the examples described herein, H is superimposed₁(S)，H₂(S)……H_n(S) different configurations derive with a new transfer function H_1,2,…n(S) filter. The derived filter represents a plurality of BPFs shifted from DC. Complex (IQ) filters may be added in series and/or in parallel to produce a complex derived BPF. The derived BPF can now be used to filter several narrower component carriers for CA while suppressing potential blockers.

The terms "derived band pass filter" and "derived BPF" as used herein refer to a filter obtained by superimposing at least one band pass filter and at least one band stop filter.

The terms "derived baseband bandpass filter" and "derived baseband BPF" as used herein refer to one derived filter obtained by superimposing at least one baseband bandpass filter and at least one baseband bandstop filter.

The terms "band-stop filter" and "BSF" as used herein include the following configurations: impedance inversion of BPFs, parallel connections, etc., which can be superimposed with other types of filters (e.g., band pass or high pass filters) to block a desired frequency range.

As used herein, the term "BPF" refers to at least one band pass filter and the term "BSF" refers to at least one band reject filter.

The term "bandwidth" as used herein refers to a frequency bandwidth.

FIG. 7 is a diagram illustrating two filters H according to an embodiment of the present invention₁(S)_BBiqAnd H₁(S)_BBiqA simplified diagram of the overlay. H₁(S)_BBiqIs a baseband quadrature (BB IQ) BPF, H₂(S)_BBiqIs a BB IQ band reject filter. The result is H_1,2(S)_BBiqIncluding two composite passbands centered symmetrically about DC.

Some embodiments of the invention use a parallel (parallel) configuration of two IQ BPFs. Wider BPFs have in-band high impedance and out-of-band low impedance, while parallel narrower BPFs have in-band low impedance and out-of-band high impedance. An alternative embodiment uses a series configuration of IQ BPF and IQ BSF. Optionally, the configuration of the derived filter comprises parallel and series components.

Alternatively, all the BPFs forming the derived BPF are identical tunable filters. The BPF can adjust for different bandwidths. Further optionally, the derived BPF includes one or more impedance inverters to invert the impedance of the narrowly tuned BPF.

Some embodiments herein are presented in terms of non-limiting embodiments of complex filters and signals. Similar embodiments may be implemented for simple (non-orthogonal) filters and signals.

The band pass filter used to generate the derivative filter may be implemented by any means known in the art. This includes, but is not limited to, implementing the BPF as an IQ low pass filter. Similarly, the band-stop filter used to generate the derivative filter may be implemented by any means known in the art. This includes, but is not limited to, implementing the BSF as an IQ high pass filter.

Referring to fig. 8A, fig. 8A is a simplified block diagram of a receiver system for generating multiple filtered signals in accordance with an embodiment of the present invention. Receiver system 800 includes a frequency converter 810 and a filtering unit 820.

The frequency converter 810, which has a Local Oscillator (LO) 830, receives a Radio Frequency (RF) signal within a first frequency bandwidth and converts the received RF signal into a second frequency bandwidth having a different center frequency. The filtering operation described herein is applied to the frequency converted signal at the output of the frequency converter 810.

Optionally, frequency converter 810 down-converts the RF signal to baseband. Further optionally, the receiver system 800 is a direct conversion receiver using single ended LO.

Filtering unit 820 generates a filtered signal by applying derived bandpass filter 825 to the signal output from frequency converter 810. Derived BPF 825 is generated by superimposing at least one BPF and at least one band-stop filter (BSF), optionally at baseband.

Optionally, the receiver system 800 further comprises a controller 840. Controller 840 changes the center frequency and/or bandwidth of derived BPF 825 by adjusting the bandwidth of at least one BPF and/or at least one BSF in filtering unit 820.

Referring to fig. 8B, fig. 8B is a simplified block diagram of a composite receiver system for generating multiple filtered signals according to an embodiment of the present invention. Receiver system 850 is similar in structure and operation to receiver system 800 of fig. 8A, except that frequency converter 870 and filter unit 860 operate in the complex plane, and LO 850 is an IQ local oscillator. The derived BPF875 is generated by superimposing at least one BPF and at least one band-stop filter (BSF), optionally at baseband.

Optionally, the one or more filters superimposed to generate the derived BPF are higher order filters. The use of higher order filters may result in a derived BPF with a steeper slope, thereby suppressing the blocker more effectively. Table 1 below shows the simulation results, showing the significant improvement in EVM when using higher order filters.

Optionally, the filtered signal encodes component carriers defined for CA, each component carrier having a bandwidth narrower than the frequency bandwidth of the RF signal. Superimposing filters with different center frequencies may produce a derived BPF that is asymmetric with respect to DC.

Fig. 9A-9C are simplified diagrams illustrating how controller 840 adjusts the derived BPF. FIG. 9A shows a tunable BPF and FIG. 9B shows a tunable BSF. The superposition of tunable filters may produce a derived BPF with a tunable bandwidth and center frequency. For simplicity, fig. 9A and 9B show the superposition of two filters with the same center frequency. Optionally, additional tunable BPFs and/or BSFs are superimposed to generate a tunable derivative BPF by superimposing three or more filters.

Optionally, the derivative filter is dynamically adjusted during CA signal reception and/or processing.

In some embodiments, controller 840 receives data from an external source, uses the data to determine which frequencies should be blocked, and adjusts the derivative filter to block unwanted frequencies. For example, the data may determine the desired frequency band and/or the desired carrier and/or the frequency to be blocked.

Alternatively or additionally, the receiver system comprises a closed loop adjustment of the derivative filter. The receiver system analyzes the received signal at RF and/or baseband frequencies, determines the frequency range to block, and adjusts the derivative filter to block the unwanted frequency range.

Optionally, BPF and/or BSF in filtering unit 820 is centered at DC (0Hz), and derived BPF 825 is shifted around the target positive and negative frequencies relative to the DC frequency.

Optionally, the BPFs and/or BSFs in the filtering unit 820 are connected to each other in a series manner. Further optionally, a matched receiver system (e.g., the exemplary embodiment of fig. 12).

Optionally, the BPF and/or BSF in the filtering unit 820 are integrated circuit components in an integrated circuit that implements a CA receiver filter in the receiver system.

Optionally, the receiver system 800 comprises at least one impedance transformer. This enables the use of impedance inversion techniques in the receiver system, as described in the embodiments below.

Optionally, the filtering unit 820 includes a composite BPF, and at least one BSF is implemented by transforming an impedance of the composite BPF. Fig. 10 illustrates the implementation of the IQ BSF as an IQ BSF by inverting impedance.

In some embodiments, receiver system 800 is implemented as an integrated circuit component in voltage mode.

Optionally, the at least one BSF and the at least one BPF are connected in parallel (e.g., the exemplary embodiment of fig. 13A).

In some embodiments, the BPF is wider than the BSF. Additionally or alternatively, the BSF and the BPF are used to generate a composite BPF of two symmetric displacements.

Optionally, receiver system 800 includes an impedance transformer for converting derived BPF 825 from a voltage mode to a current mode.

Alternatively, BPF and BSF are defined by transfer functions in the impedance domain, and derived BPF 825 defines a configurable transfer function in the impedance domain.

Optionally, the receiver system envelopes multiple BPFs. Further alternatively, the first BPF is a composite BPF covering the frequency bandwidth of the signal at the output of the frequency converter 810, and the second BPF is a composite BPF covering a narrower frequency bandwidth.

Further optionally, the receiver system includes at least one impedance inverter (e.g., the exemplary embodiment of fig. 14) connected in series to the second composite BPF.

In some embodiments, the voltage domain (high impedance within the passband and low impedance elsewhere) BPF is transformed into the voltage domain BSF by an impedance transformer. Furthermore, in some embodiments, the voltage domain BSF is used as the current domain BPF (low impedance in the passband and high impedance elsewhere) by an impedance transformer.

Optionally, the receiver system includes a CA processing unit 845 or 890 (directed to fig. 8A and 8B, respectively). The CA processing unit performs carrier aggregation signal processing of the CA signal after filtering by the filtering unit 820 or 870 (fig. 8A and 8B, respectively).

Exemplary embodiments

Some embodiments described herein are directed to systems for direct conversion through a single-ended LD. The direct conversion of RF to complex IQ baseband may comprise a low pass filter. If the mixer used for the conversion is a switch-based passive device, then such an IQLPF is a BPF for RF. Wide-band span direct conversion can be as simple as the block level in the illustration, and requires one LO and IF band. Direct conversion is illustrated in fig. 11, fig. 11 being a simplified block diagram of a direct conversion system according to some embodiments of the present invention. The RF signal is amplified by a Low Noise Amplifier (LNA) 1100 and down-converted by a mixer 1110 having a single composite LO. The down-converted signal is filtered by a complex low pass filter IQ LPF 1120.

A. Derived BPF for impedance matching

Referring to fig. 12, fig. 12 is a simplified block diagram of a derived BPF for 50ohm impedance matching according to an exemplary embodiment of the present invention.

Fig. 12 shows a derived BPF generated by connecting a tunable IQ BPF 1210 in series with a tunable IQ band-stop filter (BSF) 1250 using a bypass switch 1230. The derived BPF may be 50ohm matched, suitable for passive applications.

B. Derived BPF with high passband impedance

Referring to fig. 13A, fig. 13A is a simplified block diagram of a derived high pass-band impedance BPF according to an exemplary embodiment of the present invention. Fig. 13A shows a derived BPF 1300 generated by configuring the BPF and BSF in parallel using switches. The BSF 1310 connects the composite BPF 1320 in parallel through the IQ switch 1330. The BPF 1320 has a wider bandwidth than the BSF 1310. This results in a derived BPF with two symmetrically tunable BPFs at the output of BPF 1320.

Alternatively, BPF 1320 is a composite high impedance filter and BSF 1310 is implemented as a composite low impedance bandpass filter.

Referring to fig. 13B, fig. 13B is a simplified block diagram of a receiver system including a derived high-passband impedance BPF according to an embodiment of the present invention. The derived BPF 1300 includes a BSF 1310, a BPF 1320, and an IQ switch 1330 configured as described in fig. 13A. The RF signal (shown as the CA signal of the inband blocker) is input to a mixer 1340 connected to the IQ LO. The mixer quadrature output signals are provided to a derived BPF. At the output of the derivative filter 1300, the blocker is already greatly attenuated with respect to the useful Ch1 and Ch2 signals. The filtered signal is input to ADC 1350 for further processing.

Referring to fig. 13C, fig. 13C is a simplified block diagram of a derived high pass-band impedance BPF, according to an exemplary embodiment of the present invention. Fig. 13C shows a derived BPF 1301 generated by configuring two BPFs in parallel and using impedance inversion. The adjustable IQBPF 11350 is connected in parallel with the impedance inverter a/Z1360 through IQ switch 1370. A/Z1360 is connected in series with tunable IQ BPF 21380. As shown in FIG. 10, the series combination of A/Z1360 and BPF 21380 produces a tunable BSF.

The high impedance exemplary embodiments are generally suitable for voltage domain applications.

C. Low pass band impedance derived BPF

Referring to fig. 14, fig. 14 is a simplified block diagram of a derived low pass-band impedance BPF 1400 according to an exemplary embodiment of the present invention. The IQ BPF 1420 is connected in parallel to the IQ BSF 1430 by an IQ switch 1440. Impedance inverter A/Z1410 is connected in series to a parallel BPF/BSF configuration. A/Z1410 inverts the impedance of the voltage domain BPF to obtain the current domain BPF.

Optionally, BSF 1420 is an impedance inverting BPF as described above.

The low impedance exemplary embodiments are generally suitable for current domain applications.

D. Superposition of three filters

The exemplary embodiment described above uses two filters, however in other embodiments the derived BPF is generated by superimposing more than two filters. FIG. 15 shows a superimposed wide bandwidth BPF (Z)_BBiq1) Relatively narrow bandwidth BPF (Z)_BBiq2) And BSF (Z)_BBiq3) To produce a signal having three pass bands (Z)_BBiq) Derived BPF of (1).

Referring to fig. 16, fig. 16 is a simplified block diagram of a derived high-passband impedance BPF, according to an exemplary embodiment of the present invention. The derived BPF 1600 is generated from three BPFs (1610 to 1630) connected in parallel by a/Z1640 and a/Z1650. The bandwidths of the three BPFs decrease sequentially from BPF1 to BPF2 and then to BPF 3. The transfer function of the derived BPF has three passbands for Ch1, Ch2, and Ch 3.

This configuration may be extended to include four or more BPFs.

Data receiving method

Referring to fig. 17, fig. 17 is a simplified flowchart of a method of receiving data transmitted via RF signal combining according to an embodiment of the present invention.

At 1700, an RF signal within a frequency bandwidth is received.

Alternatively, the RF signal is received through a frequency converter employing a single-ended Local Oscillator (LO). Further optionally, the frequency converter performs a direct conversion to baseband.

At 1710, at least one BPF and at least one BSF covering a frequency bandwidth are superimposed to generate a derived BPF. Optionally, the received signal is carrier aggregated and the derived BPF is intended to pass the desired carrier band and filter out blockers between the desired bands.

At 1720, the derived BPF is applied to the RF signal to generate a filtered signal. This filtering may be applied to the RF signal, IF signal or baseband signal.

Superimposing the filter to generate the derived BPF may be performed at least in any of the ways and configurations described herein.

Simulation results

Fig. 18 to 19 show simulation results obtained by derivative filters of different orders.

Fig. 18 is a diagram of the simulation results in a real receiver scenario where the receive channel is DC-centered and requires filtering of adjacent blocker channels. Fig. 18 shows the insufficient first order filtering compared to the rejection of the blanker signal for different filter orders.

Fig. 19 shows the EVM performance of receiver scenarios employing different orders of derived BPFs. The filter stack supports CA with single ended LO direct conversion. Simulation results for the fifth order filter show that the CA filter selectivity is higher than 20 dB/dec. Table 1 shows the EVM obtained at the output of the ADC.

Order of filter	EVM(dB)
		1^st	5.12
3^rd	-10.9
		5^th	-20.1

TABLE 1

The derived filters described herein may utilize the direct conversion baseband BPFs available on-chip (e.g., for parallel reception) to reflect to IF BPFs with scalable BW and center frequency for NC CA reception. Embodiments support receiving and processing non-contiguous CA with two or more advanced wireless component carriers using a single-ended LO signal and provide lupont selectivity and scalability of bandwidth and center frequency. The frequency conversion of the CA signal may be performed by a single-ended LO and no additional LO IF signal, IF BPF or harmonic rejection IF mixer is required.

The description of the various embodiments of the present invention is intended to be illustrative, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles of the embodiments, the practical application, or technical improvements, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein, as compared to the technologies available in the market.

It is expected that during the prosecution of this patent application, many relevant superposition techniques and configurations, filters, carrier aggregation methods, receivers, impedance inverters, impedance converters, frequency translation methods, mixers, local oscillators, signal domains and RF signals will be developed, and the scope of the terms "superposition, filters, carrier aggregation, receivers, impedance inverters, impedance converters, frequency translation, local oscillators, domains and RF signals" is intended to include all such new technologies a priori.

The terms "including," comprising, "" having, "and variations thereof mean" including, but not limited to. This term includes the terms "consisting of … …" and "consisting essentially of … …".

The phrase "consisting essentially of …" means that the composition or method may include additional ingredients and/or steps, provided that the additional ingredients and/or steps do not materially alter the basic and novel characteristics of the claimed composition or method.

As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. For example, the term "compound" or "at least one compound" may comprise a plurality of compounds, including mixtures thereof.

The word "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any "exemplary" embodiment is not necessarily to be construed as preferred or advantageous over other embodiments and/or to exclude other embodiment features.

The word "optionally" is used herein to mean "provided in some embodiments but not" provided in other embodiments. Any particular embodiment of the invention may incorporate a plurality of "optional" features, unless these features contradict each other.

Throughout this application, various embodiments of the present invention may be presented in a range format. It is to be understood that the description of the range format is merely for convenience and brevity and should not be construed as a fixed limitation on the scope of the present invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as individual numbers within the range such as 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

Any numerical range recited herein is intended to include any number (fractional or integer) recited within that range. The phrases "in the first indicated number and the second indicated number range" and "in the first indicated number to the second indicated number range" are used interchangeably herein to mean to include the first and second indicated numbers and all fractions and integers in between.

It is appreciated that certain features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or in any suitable arrangement in any suitable other embodiment of the invention. Certain features described in various embodiments should not be considered essential features of those embodiments unless the embodiments are not otherwise invalid.

All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. Further, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting.

Claims

1. A receiver system for generating a plurality of filtered signals, comprising:

a Local Oscillator (LO) including a frequency converter to receive a plurality of radio frequency signals within a first frequency bandwidth and to shift the radio frequency signals to a second frequency bandwidth;

a filtering unit configured to filter the plurality of radio frequency signals within the second frequency bandwidth by applying a derived-band-pass filter (BPF) to generate a plurality of filtered signals, wherein the derived-BPF is generated by superimposing at least one BPF and at least one band-stop filter (BSF), the at least one BPF and the at least one BSF being defined according to a transfer function in an impedance domain, such that the derived-BPF defines a configurable transfer function in the impedance domain.

2. The receiver system of claim 1, further comprising a controller for adjusting a bandwidth of the at least one BPF and/or the at least one BSF to change a center frequency and a bandwidth of the derived BPF.

3. The receiver system of any preceding claim, wherein the at least one BPF and the at least one BSF are centered around a DC frequency, the derived BPF being displaced around a target positive or negative frequency relative to the DC frequency.

4. The receiver system of any of the preceding claims 1 or 2, wherein the at least one BPF and the at least one BSF are integrated circuit components in an integrated circuit, wherein the integrated circuit implements a Carrier Aggregation (CA) receiver filter of the receiver system.

5. The receiver system of claim 1 or 2, wherein the at least one BPF comprises a plurality of composite BPFs, and wherein the at least one BSF is implemented by transforming an impedance of at least one of the derived BPFs.

6. The receiver system according to claim 1 or 2, characterized by being implemented as an integrated circuit component in voltage mode.

7. The receiver system according to the preceding claim 1 or 2, characterized in that the at least one BPF is wider than the at least one BSF; and/or the at least one BSF and the at least one BPF are specifically configured to generate a composite BPF of two symmetric displacements.

8. The receiver system according to claim 1 or 2, comprising at least one impedance transformer for converting the derived BPF from a voltage mode to a current mode.

9. The receiver system according to the preceding claim 1 or 2, wherein the plurality of filtered signals encode component carriers defined for Carrier Aggregation (CA) and having a narrower bandwidth than the first frequency bandwidth.

10. The receiver system according to any of the preceding claims 1 or 2, wherein the at least one BPF comprises a first composite BPF covering the second frequency bandwidth and a second composite BPF covering a frequency bandwidth narrower than the second frequency bandwidth.

11. The receiver system of claim 10, wherein the at least one BPF and the at least one BSF are integrated circuit components, further comprising at least one impedance inverter connected in series to the second composite BPF and the at least one BSF.

12. The receiver system according to any of claims 1 to 2, wherein the at least one BPF and the at least one BSF are connected to each other in series, in particular a voltage domain BPF is transformed into a voltage domain or a current domain BSF by an impedance transformer.

13. A method of receiving data transmitted via a combination of a plurality of Radio Frequency (RF) signals, comprising:

receiving a plurality of radio frequency signals within a frequency bandwidth;

superimposing at least one band-pass filter (BPF) and a band-stop filter (BSF) covering the frequency bandwidth to generate a derived BPF, the at least one BPF and the at least one BSF being defined according to a transfer function in an impedance domain, such that the derived BPF defines a configurable transfer function in the impedance domain; and

applying the derived BPF to the plurality of radio frequency signals to generate a plurality of filtered signals.

14. The method of claim 13, wherein the plurality of radio frequency signals are received through a frequency converter comprising a single-ended Local Oscillator (LO).