CN1178413A - Amplifier system - Google Patents
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- CN1178413A CN1178413A CN 97119230 CN97119230A CN1178413A CN 1178413 A CN1178413 A CN 1178413A CN 97119230 CN97119230 CN 97119230 CN 97119230 A CN97119230 A CN 97119230A CN 1178413 A CN1178413 A CN 1178413A
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Abstract
An amplifier system for a radio receiver, comprises: an amplifier for amplifying a signal applied to an amplifier input to generate an amplifier output signal; a variable reactance means coupled between the emitter or source of the amplifier and a ground voltage; and a feedback loop for sensing the amplifier output signal and, in response to a relatively high level of the output signal, controlling the reactance of the variable reactance means to maintain the amplifier in a substantially linear mode of operation.
Description
The present invention relates to the adaptive amplifier system of a kind of amplifier system, particularly signal receiver, for example portable telephone mobile phone or satellite receiver.
Radio signal receiver generally comprises the link of filter stage and amplifier stage (" gain stage "), and the radio frequency signals of reception is serially by it.Filter stage and amplifier stage are staggered in whole link.(outside frequency band) frequency that these filter filterings are not wanted, and amplifier amplifies the signal that keeps.Result's signal is passed to frequency mixer, carry out down-conversion at this, and then with the signal demodulation.
Sensitive especially (amplifying by described link height) signal receiver may run into special problem.For the high sensitivity receiver of adaptation signal must have very low noise characteristic (being called noise factor); Otherwise noise also can be exaggerated, and makes its interference signal.Yet, be the sensitivity that obtains requiring, may need many gain stages: only in the UHF of receiver part 3 or more gain stage possibly, and general traditional mobile phone has only one or two gain stage.Such as, if will adopt three gain stage UHF parts that same principle adapts to as the reference receiver part, the performance of its IIP3 (third level input section) can be poor (may than the receiver difference 20dB that only has one or two gain stage).Therefore the sort signal receiver is highly susceptible to being subjected to undesired signal, particularly is in the interference of the signal outside the required frequency band.If the filter of signal receiver is that this problem will be sharp-pointed especially at the low insertion loss filter of wishing to have outside the frequency band less decay.
According to the present invention, a kind of amplification system of radio receiver is provided, comprising: be used to amplify the amplifier of the signal that is added to amplifier in, to produce amplifier output signal; Variable reactance mean is connected between the emitter or source electrode and earth potential of amplifier; Feedback control loop is used for the detecting amplifier output signal, and the higher level that responds this output signal is controlled the reactance of described variable reactance mean, to keep the linear mode work basically of this amplifier.
The suitable variable reactance unit that comprises of this variable reactance mean, variable-capacitance unit preferably, variable reactor is better.This variable reactance mean preferably includes a resonant circuit.This resonant circuit preferably includes inductance and capacitive element in parallel.The suitable inductance (providing) that comprises of this inductance component with one or more via holes.Preferably an element in this inductance component.The inductance of this inductance component is preferably in the scope of 0-2.5nH.1nH or less better.This capacitive element preferably includes series capacitors and variable reactor.
Best, the higher level of response output signal, this feedback control loop increases the effective inductance of this variable reactance mean.
This feedback control loop is suitable to comprise checkout gear, be used to detect described output signal level (being advisable with the voltage of signals level), and this voltage of signals is depended in generation.The most handy electric capacity of controlling described variable reactor from the control voltage that output obtained of this checkout gear.Preferably will control the end that voltage is added to variable reactor, and the other end of this variable reactor will be connected to earth potential.
This amplifier can be the part of amplifier installation, preferably includes one or more filters.This amplifier installation is the part of the chain of two or more amplifiers preferably, and in this case, described amplifier is preferably apart from the input amplifier farthest of chain.
Described amplifier preferably includes transistor, if transistor is a bipolar transistor, then this variable reactance mean should be connected between transistorized emitter and the earth potential.If this transistor is a field-effect transistor, then this variable reactance mean should be connected between transistorized source electrode and the earth potential.
Preferably, only respond the higher level of this output signal, the linearity of described feedback control loop pair amplifier has remarkable influence.
Amplifier system is suitably signal receiver, the part of radio signal receiver preferably, and this can constitute a second aspect of the present invention.Signal receiver is suitable to comprise at least two, and preferably the gain stage of at least three series connection is coupling between antenna and first (or unique) mixer device.Described amplifier is preferably near that amplifiers of those gain stages of mixer device.Preferably mixer device to received signal down-conversion so that intermediate-freuqncy signal to be provided.This amplifier system is mobile phone preferably, such as the part of radio telephone (or cellular phone or " portable telephone ") or beep-pager.
Satellite/mobile phone requires very sensitive signal receiver, and because the difference on the signal strength signal intensity between the earth radio signal, from the signal of satellite reception, because the very strong outer interference of band may run into special problem.For example, the suggestion recommendation satellite/mobile phone services at 2170-2200MHz, and the UMTS of proposed recommendations the earth/satellite phone net be operated in this frequency band near.May be apart from base station 100m UMTS signal strength signal intensity greater than-30dBm, because the general signal strength signal intensity on the earth surface of satellite/mobile phone service is-100dBm, so the UMTS letter may be rendered as strong potential interference signal for satellite/mobile phone.Therefore, can be easily amplifier system of the present invention or signal receiver be included in the receiver from the signal of satellite and/or satellite/mobile phone.
By embodiment the present invention is described in conjunction with the accompanying drawings now, wherein:
Fig. 1 is the schematic block diagram of satellite/mobile telephone system;
Fig. 2 is the schematic block diagram of satellite/mobile phone handsets;
Fig. 3 is the schematic block diagram of the part of telephone bandset shown in Fig. 2 electrical structure;
Fig. 4 has represented to be used to control the loop of the 11P3 of telephone bandset amplifier in detail;
Fig. 5 at length represents an embodiment of adaptive loop circuit;
When Fig. 6 represents that amplifier is field-effect transistor (FET) and the similar circuit of Fig. 4.
Embodiments of the invention shown in the figure are the amplifier systems that are used for satellite/mobile phone handsets.This amplifier system comprises and contains the Amplifier Gain part.A control circuit that comprises variable reactance mean is arranged, available it control the linearity of this amplifier response; With a detector that is used for the output signal level of detecting amplifier, when this level raises, increase the inductance of variable reactance mean, to improve the linearity of amplifier.
Referring to Fig. 1, satellite/mobile telephone system has the earth-orbiting satellite 1,2 that can intercom mutually, satellite 1,2 can with telephone bandset 3,4, and with landline telephone system 7,8 path 5,6 communications (in fact, this system generally has a plurality of two satellites and supports many mobile phones).By with satellite communication, mobile phone can carry out telephone communication each other, and can carry out telephone communication with the phone 9,10 that is connected to land line systems.At " Mobile P-SystemSatellite System Comparison "; International Journal of SateiliteCommunications, the 13rd volume, 453-47l page or leaf (1995) and " Mobile StarWars "; What Cellphone, has carried out general discussion to this system in the 60-66 page or leaf in September, 1996.
Use the number of satellite according to the height of satellite orbit and system, can be more than the 40000Km between any one mobile phone and the satellite that it will be communicated by letter apart from height.Therefore, compare with the earth mobile telephone system, the signal that is received by satellite/mobile phone generally has lower intensity, so be easier to be interfered.
Referring to Fig. 2, satellite/mobile phone handsets 11 (such as the telephone bandset in Fig. 13 or 4) have antenna 12; Radio frequency (RF) part 13, the signal that is used for receiving are down-converted to base band and produce by the antenna RF signals transmitted; Processor part 14 comprises the microprocessor that is used to control phone and RF partly is connected to loud speaker 15 and microphone 16.Keyboard 17 and display 18 are connected to this processor part, so that user's control circuit.
Fig. 3 has represented the RF part 13 of phone 11 in more detail.Antenna multicoupler 27 (or other suitable parts, such as switch) antenna 12 is connected to UHF radiating circuit 28 and UHF receiving circuit 29.In this receiving circuit, a band pass filter 32,33,34 and amplifier 35,36 are arranged from node 30.31 staggered chains.Enter frequency mixer 39 from the signal of node 38 output of this chain, here by with node 40 on this machine produce signal mixing this output signal down-converted to intermediate-freuqncy signal.
Interference meeting in the signal on node 30 causes maximum problem at amplifier 37, because the signal of being handled by this amplifier has passed through two gain stages.In order to help to address this problem, last gain stage has an additional control circuit 41, and detailed expression is arranged in Fig. 4.
Fig. 4 represents amplifier 37, and amplifier is wherein provided by bipolar transistor.Amplifier input terminal 42 is connected to transistorized base stage, and the output 43 of amplifier is provided from transistorized collector electrode.By resonant circuit 44 transistorized emitter is connected to ground, this resonant circuit 44 has formed the part of the adaptive loop circuit that total usefulness 45 represents.In general prior art circuits, transistorized emitter directly or with resistance is connected to ground.
In the embodiment of Fig. 4, coupler 46 is arranged on the output 43 of amplifier 31, with the output signal of detecting amplifier, this coupler provides the RF signal that comes from output 43 couplings at output 47.This coupler generally is the coupler of about 15dB.
Detector 48 is passed in the output of this coupler, and it is converted to the output of this coupler the voltage on the node 49 that relies on 43 output levels a little.This detector is such as being diode.
Voltage on the node 49 is delivered to voltage gain circuit 50 (such as an amplifier), and it amplifies the changing value of (this side says 20 times) voltage on node 49.Voltage when the voltage on the node 49 increases on the node 51 reduces.In suitable circuit, can save this voltage gain circuit 50 or provide such as an available differential amplifier.
Amplifying signal on the node 51 is connected to resonant circuit 44 at node 52.This resonant circuit has two branches in parallel.Branch is an inductance and another branch is an electric capacity.One an inductance 53 (can provide through via hole) is provided, and another branch comprises the electric capacity 54 and the variable capacitance diode 55 of series connection.Total reactance X of this resonant circuit
TOTALProvide by following formula:
Here W is a frequency, and L is the inductance of inductor, and C is the total capacitance of electric capacity branch.With the node input resonant circuit of amplifying signal between variable capacitance diode and capacitor, thereby make the variation of the voltage on the node 52 change the electric capacity of variable capacitance diode, thereby change the electric capacity tap capacitance.
To describe the operation of control circuit 41 now in detail.When the strong jamming in the signal on the node 30 arrives amplifier 37, then the voltage level at the amplifier output signal of coupler 46 inputs rises, the result on the node 47 that the coupling of the signal of node 43 comes signal level and the voltage of detector 49 outputs also rise, and the voltage of voltage gain circuit 51 outputs will descend.This will make the electric capacity of variable capacitance diode 55 increase, and it will increase the effective inductance of the emitter of amplifier 37.So because the result of the negative anti-erosion of series connection, the linearity of this amplifier (measuring such as the 11P3 by it) will be improved.This effect will be to reduce because sensitivity decline and the distortion in the output of node 43 that the strong jamming of inband signaling causes.In the adverse effect of the output of interference, this active loop will be very effective outside reducing the frequency band that not have enough to decay through filter 32,33 and antenna multicoupler 27.
Fig. 5 expresses the example of a suitable adaptive loop circuit in more detail, adopts same label with Fig. 1-4.
For common circuit, the fit value of this inductance is 0-2.5nH.When this adaptive loop circuit is driven by strong jamming, can rise to about 5V from 0V at the voltage of node 52.In order to keep this amplifier to be operated in linear mode basically, the linearity of the improved effect amplifier 37 of this loop is particularly when high signal level.When the link between transistorized emitter and the ground becomes when having more inductive, this Amplifier Gain will reduce, and this will cause the increase of the noise figure of receiver.Yet, because the total variation of the cause noise figure of the gain stage of front may be minimum.In order to help to make the minimizing minimum of high-frequency gain, the resistance value between emitter and the ground (being included in any stray resistance in the element of resonant circuit) should be low as far as possible.
Arrange this adaptive loop circuit, make it than low signal intensity (such as-90dBm) (or hardly) do not start, because 0V (or only surpassing 0V 1 point) is from detector output, so the emitter of transistor 37 level closely.So, can arrange loop to make, the obviously influence of linear few of influence of loop pair amplifier or nothing in lower signal strength signal intensity.When signal strength signal intensity raise, the effective inductance of resonant circuit 44 increased.For for example greater than the signal strength signal intensity of-15dBm, for example may be up to 5dBm, loop can cause the higher effective inductance between ground and emitter.
Coupler 46 can be arranged on after the filter 34 of follow-up amplifier 37, with the output that detects this filter rather than the direct output of amplifier 37.Adaptive loop circuit 41 can be added on any amplifier of link, detect the output of this amplifier or depend on the signal of this output, and detect the IIP3 of this amplifier.Preferably make add loop amplifier apart from antenna far, preferably be positioned at the afterbody amplifier of link as shown in Figure 3.
Fig. 6 represents the similar circuit for field effect transistor (FET) amplifier situation and Fig. 4, and same element is identical with the label of Fig. 1-5.
Present invention includes any new feature, or here significantly or implicit disclosed or their any comprehensive combination of features, and no matter whether it relevant with the invention of application, or alleviated the problem of any or all proposition.According to foregoing description, can make multiple modification for it will be readily apparent to those skilled in the art that within the scope of the invention.Such as, clearly, in the similar amplifier beyond non-bipolar transistor and the field-effect transistor, this variable reactance mean can be connected to valuably on the terminal with emitter or the similar amplifier of source electrode.
Claims (15)
1. the amplifier system of a radio receiver comprises:
Amplifier is used to amplify the signal that is added to amplifier in, to produce amplifier output signal;
Variable reactance mean is connected between the emitter or source electrode and ground voltage of amplifier;
Feedback control loop is used for the detecting amplifier output signal, responds the higher level of this output signal, controls the reactance of this variable reactance mean, to keep this amplifier basically in linear model work.
2. according to the amplifier system of claim 1, it is characterized in that described variable reactance mean comprises a resonant circuit.
3. according to the amplifier system of claim 2, it is characterized in that described resonant circuit comprises a variable capacitance diode.
4. according to the amplifier system of claim 3, it is characterized in that described feedback control loop comprises checkout gear, be used to detect output signal level, and control the capacitance of described variable capacitance diode with the voltage that output obtained of self-test device.
5. according to any one amplifier system among the claim 2-4, it is characterized in that described resonant circuit comprises inductance and the electric capacity that is connected in parallel.
6. according to any one amplifier system among the claim 2-5, it is characterized in that the reactance that described resonant circuit comprises to be provided by via hole.
7. according to the amplifier system of aforementioned arbitrary claim, it is characterized in that the higher level of feedback control loop response output signal increases the effective inductance of described variable reactance mean.
8. according to the amplifier system of above-mentioned arbitrary claim, the voltage of the feedback control loop pair amplifier output signal that it is characterized in that is responsive.
9. according to the amplifier system of above-mentioned arbitrary claim, it is characterized in that described amplifier comprises a transistor.
10. according to the amplifier system of claim 9, it is characterized in that described amplifier comprises a bipolar transistor, and described variable reactance mean is connected between transistorized emitter and the earth potential.
11., it is characterized in that described amplifier comprises a field-effect transistor, and described variable reactance mean be connected between transistorized source electrode and the earth potential according to the amplifier system of claim 10.
12. according to the amplifier system of aforementioned arbitrary claim, it is characterized in that also comprising second amplifier that is used to amplify received signal, its output is connected to the input of described amplifier.
13., it is characterized in that two described amplifiers comprise a chain of being made up of three amplifiers at least according to the amplifier system of claim 12.
14. according to the amplifier system of above-mentioned arbitrary claim, it is characterized in that comprising an antenna that is used to receive radio signals, be connected to described amplifier in.
15. according to the amplifier system of above-mentioned arbitrary claim, it is characterized in that comprising a mixer arrangement, its input is coupled into and receives the signal that depends on amplifier output signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 97119230 CN1178413A (en) | 1996-09-20 | 1997-09-20 | Amplifier system |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9619705.8 | 1996-09-20 | ||
| CN 97119230 CN1178413A (en) | 1996-09-20 | 1997-09-20 | Amplifier system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1178413A true CN1178413A (en) | 1998-04-08 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 97119230 Pending CN1178413A (en) | 1996-09-20 | 1997-09-20 | Amplifier system |
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| Country | Link |
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| CN (1) | CN1178413A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101057396B (en) * | 2004-09-10 | 2012-07-18 | 卡莱汉系乐有限公司 | Tunable cascode LNA with flat gain response over a wide frequency range |
| CN108141185A (en) * | 2015-10-05 | 2018-06-08 | 瑞典爱立信有限公司 | Amplifying device including amplitude limit |
-
1997
- 1997-09-20 CN CN 97119230 patent/CN1178413A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101057396B (en) * | 2004-09-10 | 2012-07-18 | 卡莱汉系乐有限公司 | Tunable cascode LNA with flat gain response over a wide frequency range |
| CN108141185A (en) * | 2015-10-05 | 2018-06-08 | 瑞典爱立信有限公司 | Amplifying device including amplitude limit |
| CN108141185B (en) * | 2015-10-05 | 2021-08-03 | 瑞典爱立信有限公司 | Amplifying device including clipping |
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