CN1145258C - Bias circuit for RF power amplifier - Google Patents
Bias circuit for RF power amplifier Download PDFInfo
- Publication number
- CN1145258C CN1145258C CNB01117949XA CN01117949A CN1145258C CN 1145258 C CN1145258 C CN 1145258C CN B01117949X A CNB01117949X A CN B01117949XA CN 01117949 A CN01117949 A CN 01117949A CN 1145258 C CN1145258 C CN 1145258C
- Authority
- CN
- China
- Prior art keywords
- frequency
- biasing circuit
- radio
- operational amplifier
- power amplifier
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
- H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/451—Indexing scheme relating to amplifiers the amplifier being a radio frequency amplifier
Abstract
Bias circuit for RF power amplifier in the battery supply unit of the radio communication system. The bias circuit comprises an operational amplifier providing the bias for RF power amplifier and at the same time the operational amplifier is exposed in the input RF signals. The operatial amplifier has little influence on the RF signals since its approximate frequency compensation.
Description
The present invention relates generally to radio-frequency power amplifier, particularly, relates to the biasing circuit of the radio-frequency power amplifier that the powered battery mobile phone unit that is used to be suitable for wireless communication system uses.
In the prior art, be used for the biasing circuit of radio-frequency power amplifier,, disclose in 648, use structure shown in Figure 1 such as United States Patent (USP) 5,629.Such biasing circuit comprises electric capacity 10 and blocks inductance 12.Blocking inductance 12 stops the biasing circuit by radio frequency amplifier to load radiofrequency signal.And, block inductance 12 and stop radiofrequency signals to enter biasing circuit, wherein radiofrequency signal may by rectification or cause biasing undesired, that depend on the radiofrequency signal amplitude move.
Biasing circuit, all biasing circuits as shown in Figure 1 provide quite high bias plasma resistance.Be in the adjacent channel frequency difference (for example, 980kHz in the U.S.) frequency, also promptly in J-CDMA the impedance of the biasing circuit on the difference frequency of interference channel can significantly be reduced by using big discrete capacitor in parallel 10 (such as 4.7 μ F).In this respect, know, near the difference frequency of adjacent channel frequency, can worsen the intermodulation of radio-frequency power amplifier and adjacent channel power than (ACPR) performance much larger than several ohm biasing impedances.Intermodulation and ACPR relate to the linearity of radio-frequency power amplifier, and particularly, ACPR is considerable in linear power amplifier is used.
Nearest progress is the radio-frequency power amplifier that is used for battery powered mobile phone, and it has two signal path, and every paths operates on the different power levels, and signal is directed into antenna by this path, so that send to the base station that this mobile phone is communicated by letter with it.The position of mobile phone with respect to the base station depended in the selection that is used for the signal path of specific transmission.When mobile phone is positioned at apart from the base station predetermined distance, selects lower power level signal path, and when mobile phone is positioned at apart from the base station predetermined distance in addition, select higher power level signal path.Like this, mobile phone only consumes necessary quantity of power, and battery can be worked the longer time interval between twice charging.
For this radio-frequency power amplifier that is operated on one of two power levels, another requirement of biasing circuit is, biasing circuit provides low-resistance on the difference frequency of adjacent channel frequency, when being biased in when switching between two radio-frequency power amplifiers in the power level signal path, also provide switching time less than 2 microseconds.This need be a progression of seamlessly adjusting radio-frequency power amplifier owing to wish the change of exporting in response to the radio-frequency power of needs.If radio-frequency power amplifier needs long switching time, then the radio-frequency power amplifier from a signal path is transferred to the losing of information that another radio-frequency power amplifier in another signal path can cause being sent to by mobile phone the base station.In order in 5 microseconds, to switch the about 800 millivolts voltage of 4.7 μ F electric capacity, need to surpass 0.5 ampere electric current.Under the environment to power and electromagnetic interference sensitivity, this is unacceptable.
Therefore, the purpose of this invention is to provide and be used for radio-frequency power amplifier, novel and improved biasing circuit.
Another object of the present invention provides the biasing circuit that is used for radio-frequency power amplifier, and it has overcome the defective that is used for the biasing circuit of radio-frequency power amplifier in the prior art.
In order to reach these and other objects, make up according to the present invention, be used for the powered battery mobile phone unit of wireless communication system, the biasing circuit of radio-frequency power amplifier, comprise the operational amplifier that is added with the input radio frequency signal on it, and the transistor source follower circuit that is connected to the output of operational amplifier.Operational amplifier has a dominant pole frequency, it causes the output at biasing circuit, impedance on the difference frequency of adjacent channel is not more than 2 ohm, and this frequency ratio to play the frequency of radio frequency signal much lower so that the loop gain less than zero dB is arranged on the frequency of radiofrequency signal.This radio frequency loading of guaranteeing biasing circuit minimizes.
Can understand the present invention best during detailed description below reading in conjunction with the accompanying drawings.
Fig. 1 is the circuit diagram of traditional, as to be used for radio-frequency power amplifier biasing circuit.
Fig. 2 makes up according to the present invention, is used for the powered battery mobile phone unit of wireless communication system, the circuit diagram of radio-frequency power amplifier biasing circuit.
Fig. 3 is the circuit diagram that can be used in the operational amplifier of biasing circuit shown in Figure 2.
With reference to Fig. 2, make up according to the present invention, be used for the powered battery mobile phone unit of wireless communication system, the biasing circuit of radio-frequency power amplifier, comprise the operational amplifier 20 that is added with the input radio frequency signal on it, and the transistor source follower output circuit 22 that is connected to the output of operational amplifier.
The transistor of transistor source follower output circuit preferably has maximum, non-wasting drain current limited characteristic.This transistor can be, and is for example shown, field-effect transistor (FET, JFET, NFET, or MOSFET).Field-effect transistor has the maximum drain current characteristic, and will transship so that source voltage descends when overload condition.Avoid when radio-frequency power amplifier transships, continuing to provide the transistor of bias voltage to the radio-frequency power amplifier base stage.The correct biasing circuit transistor of selecting will remove (debias) partially for radio-frequency power amplifier, rather than allow radio-frequency power amplifier to damage under overload condition.
The dominant pole frequency of operational amplifier is much lower compared with the radio frequency signal frequency of input, so that the loop gain less than zero dB is arranged on the input radio frequency signal frequency.This has reduced the loading of biasing circuit to RF signal path.Beyond the loop bandwidth of operational amplifier 20, according to improved biasing circuit of the present invention, with about 1/Gm of transistor source follower output circuit as the load of giving RF signal path.In JCDMA used, this was 50 ohm of rf bias that are loaded into the SiGe power HBT with about 1 ohm to 2 ohm 900MHz impedance of fundamental frequency, and it is slight load.
On the frequency (for example 900MHz) of radiofrequency signal, be rendered as open circuit according to biasing circuit of the present invention basically.
The analysis showed that of operational amplifier 20, more than the dominant pole frequency of operational amplifier, the output impedance of transistor source follower output circuit is rendered as emotional resistance, and is as described below.
More generally, the open-loop gain of operational amplifier can be with having a dominant pole, depends on frequency, and the expression approximate representation is:
Wherein Ro and Co are the operational amplifier parasitic parameters, and they determine dominant pole frequency.
For f<≈ Av/ (2 π fRoCo), molecule is preponderated, and circuit is perceptual.
Fig. 3 is the circuit diagram that can be used in the operational amplifier of biasing circuit shown in Figure 2.It will be apparent to those skilled in the art that this operational amplifier is traditional design and structure.Therefore, the detail of this operational amplifier is optional.As long as say the operational amplifier that this operational amplifier is preferably very lower powered, required impedance operator is provided.Though in the biasing circuit that other many structures can be used to make up according to the present invention, the importantly setting of the pole and zero in the operational amplifier response function or do not have pole and zero, and the response of the k factor of combined bias circuit and rf gain level.Should see, dominant pole frequency, for example 60kHz is established by flow through low-down current density (for example about altogether 20 microamperes) in operational amplifier.Though this is convenient to the emulation convergence, higher bias level and bigger output capacitance also should be suitable embodiments.Because operational amplifier 20 is not subjected to the influence of radiofrequency signal, the radio-frequency power amplifier that is operated on the relative higher power level (for example 500 milliwatts) can be adjusted by the biasing circuit that is operated on the relatively low power level (for example 60 microwatts).
In a word, operational amplifier provides biasing for radio-frequency power amplifier, and operational amplifier is exposed in the radiofrequency signal of input simultaneously.The operational amplifier quilt is frequency compensation approx, so that to almost not influence of RF signal path.
Though show and described the present invention with reference to some exemplary embodiments, in any case, the invention is not restricted to details shown and that describe.But can in the full scope of equivalents of claim, make various modifications to those exemplary embodiments, and do not deviate from the present invention.
Claims (3)
1. be used for the biasing circuit of the radio-frequency power amplifier of the battery powered mobile phone unit of wireless communication system, comprise:
Operational amplifier is added with the input radio frequency signal with dominant pole frequency, this dominant pole frequency on it
(a), on the difference frequency of adjacent channel, produce and be not more than 2 ohm impedance at the biasing circuit output; And
(b) more much lower than radio frequency signal frequency, to such an extent as on the frequency of radiofrequency signal, have loop gain less than zero dB;
This biasing circuit also comprises transistor source follower output circuit, is connected to the operational amplifier output terminal place.
2. according to the biasing circuit of claim 1, the transistor of wherein said transistor source follower output circuit has the characteristic in the non-destructive scope that maximum with its drain current is limited in this drain current.
3. according to the biasing circuit of claim 1, it is characterized in that the transistor of wherein said transistor source follower output circuit is a field-effect transistor.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US56009800A | 2000-04-28 | 2000-04-28 | |
US09/560098 | 2000-04-28 | ||
US09/560,098 | 2000-04-28 |
Publications (2)
Publication Number | Publication Date |
---|---|
CN1346176A CN1346176A (en) | 2002-04-24 |
CN1145258C true CN1145258C (en) | 2004-04-07 |
Family
ID=24236355
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CNB01117949XA Expired - Fee Related CN1145258C (en) | 2000-04-28 | 2001-04-27 | Bias circuit for RF power amplifier |
Country Status (2)
Country | Link |
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KR (1) | KR100392208B1 (en) |
CN (1) | CN1145258C (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7274258B2 (en) * | 2005-09-08 | 2007-09-25 | Industrial Technology Research Institute | Dynamic bias circuit for a radio-frequency amplifier |
CN103226326A (en) * | 2013-03-11 | 2013-07-31 | 上海电力学院 | Frequency domain analysis method for ship autopilot system |
CN105684302A (en) * | 2013-11-04 | 2016-06-15 | 马维尔国际贸易有限公司 | Memory effect reduction using low impedance biasing |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5493255A (en) * | 1995-03-21 | 1996-02-20 | Nokia Mobile Phones Ltd. | Bias control circuit for an RF power amplifier |
JPH08288772A (en) * | 1995-04-14 | 1996-11-01 | Goyo Denshi Kogyo Kk | Bias control circuit for transmission power amplifier |
JP2720851B2 (en) * | 1995-10-25 | 1998-03-04 | 日本電気株式会社 | Amplifier bias current control circuit |
KR19990004266A (en) * | 1997-06-27 | 1999-01-15 | 이형도 | High frequency amplification circuit in wireless communication terminal |
-
2001
- 2001-03-27 KR KR10-2001-0015867A patent/KR100392208B1/en not_active IP Right Cessation
- 2001-04-27 CN CNB01117949XA patent/CN1145258C/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
KR100392208B1 (en) | 2003-07-22 |
CN1346176A (en) | 2002-04-24 |
KR20010098427A (en) | 2001-11-08 |
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