CN202121602U - Device for calibrating mismatch of modem - Google Patents
Device for calibrating mismatch of modem Download PDFInfo
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- CN202121602U CN202121602U CN2011201610020U CN201120161002U CN202121602U CN 202121602 U CN202121602 U CN 202121602U CN 2011201610020 U CN2011201610020 U CN 2011201610020U CN 201120161002 U CN201120161002 U CN 201120161002U CN 202121602 U CN202121602 U CN 202121602U
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Abstract
The utility model relates to a device for calibrating mismatch of a modem. A signal output end of an emitter of the modem is connected to a signal input end of a receiver of the modem in a feedback connection manner. I/Q orthogonal signals needed for a phase-shift network to generate modulation and demodulation are respectively arranged on lines from which a clock generator correspondingly supplies local oscillation signals for the receiver and the emitter. Output signals of the emitting end, which are processed by I/Q quadrature modulation, are inputted to the receiver in a feedback manner, two paths of baseband signals are obtained after I/Q quadrature demodulation treatment on the output signals of the emitting end, and then algebraic operation is conducted on the received signals to realize measuring and compensation of phase and range offset of the emitting end and the receiving end. With no circuit of the modem needing to be constructed and no power consumption needing to be increased, the device can eliminate the influence of offset, can increase data transmission rate of the modem and reduce power consumption of the circuit, and can also reduce intensity of interference signals of the modem and improve image frequency rejection ratio.
Description
Technical Field
The utility model relates to an integrated circuit, in particular to calibrating device of modem mismatch.
Background
Currently, CMOS modems on the signal path can suffer from mismatch due to process tolerances, thereby affecting modem performance.
Particularly when mismatches occur in the quadrature path of the baseband portion of the modem, such as the baseband filters, baseband D/a and a/D converters, up-conversion mixers, down-conversion mixers, and quarter clock signals of the controlled mixers. These mismatches can cause signal distortion such that signals at one frequency are replicated to other frequencies.
For example, when the quadrature baseband signal is 10MHz, the output signal should be a single frequency signal of 1.01GHz by performing up-conversion with a local oscillator of 1GHz through a biorthogonal mixer.
However, due to the mismatch, a 990MHz spurious signal is generated. Its phase and amplitude are determined by the magnitude and type of modem mismatch introduced.
For example, when there is an amplitude mismatch in the baseband filter, the desired signal will be phase distorted; however, if the quadrature mixers are not phase matched, the output signal will be phase shifted by 90 ° compared to the expected signal.
If both receiver and transmitter are provided on our chip, we need to describe the performance of the following parts:
receiver quadrature phase amplitude mismatch;
receiver quadrature phase mismatch;
the transmitter quadrature phase amplitudes are not matched;
the transmitter quadrature phase is not matched.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a calibration device of modem mismatching, which carries out algebraic operation on the received signal of the modem and extracts four unmatched specific parameters of the quadrature phase amplitude value and the phase of the receiver and the transmitter; thus, the mismatch can be compensated for in transmission and reception according to the estimation of the mismatch parameter, so as to improve the quality of the signal, reduce power consumption, and obtain a high data transmission rate.
In order to achieve the above object, the present invention provides a calibration apparatus for modem mismatch, which comprises an attenuation network and two phase shift networks added in a transmitter and a receiver of a modem;
wherein the attenuation network connects the signal output end of the transmitter of the modem to the signal input end of the receiver of the modem in a feedback way;
and the two phase shifting networks are respectively arranged on a line which correspondingly provides local oscillation signals for the receiver and the transmitter by the clock generator.
A module for transmitting a digital baseband signal, a D/A converter, a low-pass filter and a plurality of stages of amplifiers are sequentially arranged in a transmitter of the modem according to the trend of a transmission signal;
the clock generator mixes the two paths of orthogonal local oscillation signals generated by the phase-shifting network with the output signal of the low-pass filter, and then superposes the two paths of orthogonal local oscillation signals to obtain the output signal of the transmitting end; the output end of the amplifier is connected to the receiver of the modem in a feedback mode through the attenuation network, and the output signals of the transmitting end after amplification processing are respectively used as receiving end input signals of the receiver.
The receiver of the modem is sequentially provided with a plurality of stages of amplifiers, a low-pass filter, an A/D converter and a module for receiving digital baseband signals according to the trend of received signals;
and the clock generator mixes the two orthogonal demodulation signals generated by the other phase-shifting network with the amplified receiving end input signal to obtain two receiving end baseband signals for mismatch parameter estimation.
Compared with the prior art, the calibrating device of modem mismatch, its advantage lies in: the utility model discloses need not establish the circuit of modem in addition, also need not increase the consumption, the transmitting terminal output signal before and after will moving phase respectively, the feedback is input the receiver department and is obtained two baseband signals, through carrying out algebraic operation to this received signal, realizes measuring and compensating to the phase place and the amplitude skew of transmitting terminal and receiving terminal, has not only removed the influence of these offsets, has still increased modem data transmission's speed, has reduced the consumption of circuit; it may also help to reduce the modem's interference signal strength and improve the image rejection ratio.
Drawings
Fig. 1 is a circuit block diagram of a calibration apparatus for modem mismatch according to the present invention.
Detailed Description
Modem mismatch's calibrating device is particularly useful for the condition that is provided with receiver and transmitter on the modem chip simultaneously, right four kinds of mismatching of quadrature phase amplitude and the phase place of receiver and transmitter are calibrated.
Referring to fig. 1, the calibration apparatus includes an attenuation network and two phase shift networks added in a transmitter and a receiver of a modem; wherein the attenuation network connects the signal output end of the transmitter of the modem to the signal input end of the receiver of the modem in a feedback way; and the two phase shifting networks are respectively arranged on a line which correspondingly provides local oscillation signals for the receiver and the transmitter by the clock generator.
Specifically, a module for transmitting a digital baseband signal, a D/a converter, a low-pass filter, and a plurality of stages of amplifiers are sequentially disposed in a transmitter portion of the modem according to a direction of a transmission signal; the clock generator is connected with the output end of the low-pass filter through a phase shifting network. Modulating the baseband signal after the corresponding processing of the D/A converter and the low-pass filter by the orthogonal signal of the local oscillation signal after phase shifting, and obtaining a transmitting end output signal after signal amplification, and feeding back and inputting the transmitting end output signal to a receiver of the modem through an attenuation network.
The receiver part of the modem is sequentially provided with a plurality of stages of amplifiers, a low-pass filter, an A/D converter and a module for receiving digital baseband signals according to the trend of received signals; the clock generator is connected with the input end of the low-pass filter through another phase shifting network. And demodulating the amplified input signal by an orthogonal signal of the local oscillation signal, and performing corresponding processing by the low-pass filter and the A/D converter to obtain a digital baseband signal.
The method for calibrating the mismatch of the modem according to the present invention is described below with reference to the block diagram structure of the calibration apparatus shown in fig. 1, and comprises the following steps:
step 1, in the transmitter part of the modem, a clock generator outputs a local oscillation signal LO for a terminal baseband signal of the transmitter after filtering and D/A conversion processingV TX,BB Modulating, and amplifying to obtain output signal of transmitting terminal；
Step 2, outputting the signal from the transmitting terminalFeeding back the input signal to the receiver part of the modem as its input signal through an attenuation network
；
Step 3, the clock generator is a local oscillation signal LO correspondingly output by the receiver, and the amplified receiving end input signal is
Demodulating and filtering to obtain baseband signal of receiving endV RX,BB ；
Step 4, providing a local oscillation signal LO provided by a clock generator for the transmitter, and a baseband signal of the transmitterV TX,BB Simultaneously performing phase shift;
step 5, the local oscillation signal LO after phase shift in step 4 is used as the baseband signal after phase shiftV TX,BB Modulating, amplifying to obtain phase-shifted output signal of transmitting terminal
；
Step 6, similar to step 2, modulating the phase-shifted output signal of the transmitting end
Also fed back to the receiver part of the modem via an attenuation network as a phase-shifted input signal
；
Step 7, similar to step 3, the local oscillation signal LO correspondingly output by the clock generator as the receiver is used for amplifying the phase-shifted receiving end input signal obtainedDemodulating and filtering to obtain the phase-shifted baseband signal of the receiving endV RX,BB ；
Step 8, rootAccording to the receiving end baseband signals before and after phase shifting obtained in step 3 and step 7 respectivelyV RX,BB Four mismatch parameters of the quadrature phase amplitude and phase of the receiver and transmitter are calculated.
The following gives a specific calculation formula based on the above method. Suppose that the four quadrature signals of the local oscillation signal LO for signal modulation at the transmitting end generated by the clock generator in step 1 are
Wherein,is the oscillation frequency of the local oscillation signal LO.
If there is no mismatch at the transmitting end, the output signal of the transmitting end mixed by the local oscillation signal LO should be
Wherein,
is the incoming baseband signal frequency.
Because of mismatch at the transmitting end, after the baseband signal is modulated by the local oscillation signal LO, the output signals of the transmitting end are obtained as follows:
wherein,
representing the amplitude mismatch parameter of the transmitter,
representing the phase mismatch parameter of the transmitter.
The output signal of the unmatched transmitting terminal is approximate to
As stated in step 2, the transmitting end outputs signals
Feedback is input to the receiver of the modem as its input signal. Assuming that the four orthogonal signals of the local oscillation signal LO generated by the clock generator in step 3 for the demodulation of the signal at the receiving end are:
wherein,
is the oscillation frequency of the local oscillation signal LO,is the phase of the local oscillator signal.
Input signal of receiving end
After the local oscillation signal LO frequency mixing of the receiving end, the baseband signal of the receiving end is obtained through demodulation:
Then, as described in steps 4-5, the local oscillation signal LO and the baseband signal V of the transmitter are processedTX，BBThe phase shift is carried out simultaneously through a phase shift network, and the phase-shifted local oscillation signal LO is a phase-shifted baseband signalV TX,BB Modulating, and obtaining the phase-shifted output signal of the transmitting end at the moment
（8）
In step 6-7, outputting the phase-shifted transmitting end output signal
Also feeding back to the receiver, after the demodulation of the local oscillator signal LO of the receiver as described in equation 5, the received baseband signal at this time will become:
as shown in step 8, to derive mismatch parameters in the modem process
，
，
，
Suppose that
At this time, algebraically operating the received signal, i.e. substituting equation 7 into equation 11, we can obtain the mismatch parameter
，
，
，
The specific numerical value of (1). Thus, the mismatch can be compensated for in signal transmission and reception according to the mismatch parameters.
Therefore, the utility model discloses need not establish the circuit of modem in addition, also need not increase the consumption, the transmitting terminal output signal around will moving the phase respectively, the feedback is input the receiver department and is obtained two baseband signals, through carrying out algebraic operation to this received signal, realizes measuring and compensating to the phase place and the amplitude skew of transmitting terminal and receiving terminal, not only has removed the influence of these offsets, has still increased modem data transmission's speed, has reduced the consumption of circuit; it may also help to reduce the modem's interference signal strength and improve the image rejection ratio.
While the present invention has been described in detail with reference to the preferred embodiments thereof, it should be understood that the above description should not be taken as limiting the present invention. Numerous modifications and alterations to the present invention will become apparent to those skilled in the art upon reading the foregoing description. Accordingly, the scope of the invention should be limited only by the attached claims.
Claims (3)
1. A calibration device for modem mismatch is characterized in that the calibration device comprises an attenuation network and two phase shift networks which are additionally arranged in a transmitter and a receiver of a modem;
wherein the attenuation network connects the signal output end of the transmitter of the modem to the signal input end of the receiver of the modem in a feedback way;
and the two phase shifting networks are respectively arranged on a line which correspondingly provides local oscillation signals for the receiver and the transmitter by the clock generator.
2. The apparatus for calibrating mismatch between modems according to claim 1, wherein a module for transmitting a digital baseband signal, a D/a converter, a low pass filter, and a plurality of stages of amplifiers are sequentially provided in a transmitter of the modem in accordance with a direction of a transmission signal;
the clock generator mixes the two paths of orthogonal local oscillation signals generated by the phase-shifting network with the output signal of the low-pass filter, and then superposes the two paths of orthogonal local oscillation signals to obtain the output signal of the transmitting end; the output end of the amplifier is connected to the receiver of the modem in a feedback mode through the attenuation network, and the output signals of the transmitting end after amplification processing are respectively used as receiving end input signals of the receiver.
3. The apparatus for calibrating mismatch between modems according to claim 2, wherein a plurality of stages of amplifiers, low pass filters, a/D converters, and a module for receiving digital baseband signals are sequentially disposed in a receiver of the modem in accordance with the direction of a received signal;
and the clock generator mixes the two orthogonal demodulation signals generated by the other phase-shifting network with the amplified receiving end input signal to obtain two receiving end baseband signals for mismatch parameter estimation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011201610020U CN202121602U (en) | 2011-05-19 | 2011-05-19 | Device for calibrating mismatch of modem |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011201610020U CN202121602U (en) | 2011-05-19 | 2011-05-19 | Device for calibrating mismatch of modem |
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| CN202121602U true CN202121602U (en) | 2012-01-18 |
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| CN2011201610020U Expired - Lifetime CN202121602U (en) | 2011-05-19 | 2011-05-19 | Device for calibrating mismatch of modem |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102340467A (en) * | 2011-05-19 | 2012-02-01 | 乐鑫信息科技（上海）有限公司 | Device and method for calibrating mismatched modem |
| WO2022000529A1 (en) * | 2020-07-03 | 2022-01-06 | 锐迪科创微电子（北京）有限公司 | Amplitude offset calibration method, device and storage medium |
-
2011
- 2011-05-19 CN CN2011201610020U patent/CN202121602U/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102340467A (en) * | 2011-05-19 | 2012-02-01 | 乐鑫信息科技（上海）有限公司 | Device and method for calibrating mismatched modem |
| WO2022000529A1 (en) * | 2020-07-03 | 2022-01-06 | 锐迪科创微电子（北京）有限公司 | Amplitude offset calibration method, device and storage medium |
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| C14 | Grant of patent or utility model | ||
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| CP01 | Change in the name or title of a patent holder |
Address after: Room 403, No. 2966 Jinke Road, Zhangjiang High-tech Park, Pudong New Area, Shanghai, 201203 Patentee after: Lexin Information Technology (Shanghai) Co., Ltd. Address before: Room 403, No. 2966 Jinke Road, Zhangjiang High-tech Park, Pudong New Area, Shanghai, 201203 Patentee before: Yue Xin information technology (Shanghai) Co., Ltd. |
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| CP01 | Change in the name or title of a patent holder | ||
| CX01 | Expiry of patent term |
Granted publication date: 20120118 |
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| CX01 | Expiry of patent term |