CN103944522A - Power amplifier - Google Patents
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- CN103944522A CN103944522A CN201410188575.0A CN201410188575A CN103944522A CN 103944522 A CN103944522 A CN 103944522A CN 201410188575 A CN201410188575 A CN 201410188575A CN 103944522 A CN103944522 A CN 103944522A
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Abstract
The invention discloses a power amplifier which comprises a first resistor, a choke inductor, a first transistor, an input coupling circuit and an output coupling circuit. The first resistor, the choke inductor and the first transistor are connected between the power source end and the ground in series. The input coupling circuit is connected between the input end of the power amplifier and the grid electrode of the first transistor. The output coupling circuit is connected among the output end of the power amplifier, the chock inductor and a first middle node of the first transistor. The power amplifier further comprises a biasing circuit connected with the grid electrode of the first transistor, so that a working point of the first transistor changes along with the change of the supply voltage. According to the power amplifier, the voltage resistant requirement of the first transistor can be lowered, the direct current component of an output signal of the first middle node of the first transistor is approximately equal to a half of the supply voltage so as to ensure the output power of the power amplifier, and reliability and linearity can be improved.
Description
Technical field
The present invention relates to electronic circuit, relate to particularly power amplifier.
Background technology
Power amplifier is typically used as audio frequency amplifier and radio frequency amplifier, for generation of power stage to drive load.In radio frequency applications field, power amplifier is necessary module, before transmitting, signal is amplified, and then amplifying signal can be coupled to antenna.
The mode of operation classification of pressing power amplifier, power amplifier can be divided into category-A, category-B, AB class, C class, D class, E class etc.The kind of power amplifier is different, and the voltage waveform of its output is also different.The amplitude of the output waveform of power amplifier may reach 2～4 times of supply voltage, thus require power transistor in power amplifier withstand voltage should be also supply voltage 2-4 doubly.
For some consumer electronics products, when using battery, supply voltage may change in wide region.In full electricity, supply voltage can reach 7V or higher.Yet when battery runs low, supply voltage can drop to 2V left and right.In order to adapt to the mains voltage variations of wide region, need to be according to the transistorized withstand voltage parameter of maximum mains voltage design power.Yet requiring operating frequency height and withstand voltage height on common process is a difficult thing simultaneously.Adopt more advanced technique can increase cost, and be unfavorable for integrated.
On the other hand, because load is in use normally fixing.If mains voltage variations scope is large, also can make the load off-target load value of power amplifier.The possibility of result reduces power output, and makes the linearity variation of power stage.
Therefore, expectation reduces the requirement of withstand voltage of the power transistor in power amplifier and the linearity of improving power stage.
Summary of the invention
The object of the present invention is to provide a kind of power amplifier that can expansion of power supply voltage range.
According to the present invention, a kind of power amplifier is provided, comprising: the first resistance, choke induction and the first transistor that between power end and ground, are connected in series; Be connected to the input coupling circuit between the input of power amplifier and the grid of the first transistor; And be connected to the output coupling circuit between the output of power amplifier and the first intermediate node of choke induction and the first transistor, wherein, described power amplifier also comprises the biasing circuit being connected with the grid of the first transistor, makes the working point of the first transistor follow the variation of supply voltage.
Preferably, in described power amplifier, described biasing circuit comprises: be connected in series in the second resistance and transistor seconds between feeder ear and ground, the second intermediate node between the second resistance and transistor seconds produces and detects voltage; Be connected to the 3rd resistance of the grid of transistor seconds; Be connected to the 4th resistance of the grid of the first transistor; And operational amplifier, its in-phase end receives and detects voltage, and its end of oppisite phase receives reference voltage, and its output is connected to the grid of transistor seconds via the 3rd resistance, and the grid that is connected to the first transistor via the 4th resistance.Preferably, in described power amplifier, half that described reference voltage is supply voltage.Preferably, in described power amplifier, the first transistor is identical with the conduction type of transistor seconds.Preferably, in described power amplifier, the product of the resistance value of the first resistance and the breadth length ratio of the first transistor, equals the product of the resistance value of the second resistance and the breadth length ratio of transistor seconds.
Preferably, in described power amplifier, described biasing circuit comprises: be connected in series in the second resistance and transistor seconds between feeder ear and ground; And be connected to the 3rd resistance between the grid of the first transistor and the grid of transistor seconds, wherein, the grid of transistor seconds is also connected to the intermediate node of the second resistance and transistor seconds, and the first transistor and transistor seconds form current mirror, current mirror is adjusted the working point of the first transistor, makes the first ohmically voltage drop be substantially equal to all the time half of supply voltage.Preferably, in described power amplifier, the first transistor is identical with the conduction type of transistor seconds.Preferably, in described power amplifier, the product of the resistance value of the first resistance and the breadth length ratio of the first transistor, equal the resistance value of the second resistance and the breadth length ratio of transistor seconds product 1/2.
Preferably, in described power amplifier, described input coupling circuit comprises capacitance.
Preferably, in described power amplifier, described output coupling circuit comprises at least one in capacitance and load matched resistance.
Preferably, in described power amplifier, described output coupling circuit comprises matched filtering circuit.
In power amplifier of the present invention, due to the effect of above-mentioned biasing circuit, the DC component that produces amplifying signal at the intermediate node of choke induction and the first transistor is relevant to supply voltage, and is substantially equal to all the time supply voltage half.The requirement of withstand voltage of the first transistor reduces.The variation of supply voltage can be followed in the working point of this power amplifier, thereby can guarantee the power output of power amplifier, and improves reliability and the linearity.
Accompanying drawing explanation
By the description to the embodiment of the present invention referring to accompanying drawing, above-mentioned and other objects of the present invention, feature and advantage will be more clear, in the accompanying drawings:
Fig. 1 is according to the schematic circuit of the power amplifier of prior art;
Fig. 2 is according to the exemplary waveform diagrams of the power amplifier of prior art;
Fig. 3 is the schematic block diagram of power amplifier according to an embodiment of the invention;
Fig. 4 is the first example of power amplifier according to an embodiment of the invention; And
Fig. 5 is the second example of power amplifier according to an embodiment of the invention.
Embodiment
Hereinafter with reference to accompanying drawing, various embodiment of the present invention is described in more detail.In each accompanying drawing, identical element adopts same or similar Reference numeral to represent.For the sake of clarity, the various piece in accompanying drawing is not drawn in proportion.
Fig. 1 is according to the schematic circuit of the power amplifier of prior art.This power amplifier comprise the first transistor M1 and choke induction L1, the input coupling circuit being electrically connected to the grid of the first transistor M1 being connected in series and be connected to the first transistor M1 and the intermediate node of choke induction L1 on output coupling circuit.
Input coupling circuit for example comprises the first capacitor C 1 being connected between the input of power amplifier and the grid of the first transistor M1.The grid of the first transistor M1 is also connected with biasing resistor R0.Bias voltage Vb is applied to via biasing resistor R0 on the grid of the first transistor M1, for the working point of the first transistor M1 is set.Output coupling circuit can comprise be connected to intermediate node and the second capacitor C 2, the matched filtering circuit 101 between output of the first transistor M1 and choke induction L1 and be connected to output and ground between load matched resistance R L.The first capacitor C 1 and the second capacitor C 2 all play the effect that cuts off direct current.
Fig. 2 is according to the exemplary waveform diagrams of the power amplifier of prior art.When work, the input of power amplifier receives ac input signal Vin.Intermediate node at the first transistor M1 and choke induction L1 produces amplifying signal VA.At the first transistor M1, be under the situation of N-type MOSFET, this intermediate node is the drain electrode of the first transistor M1.According to the bias state of the first transistor M1, the output signal VA of the first transistor M1 comprises DC component VCCA.Through the second capacitor C 2, remove DC component VCCA, at the output generation alternating current output signal VOUT corresponding with ac input signal Vin of power amplifier.
When work, when this power amplifier is in static time, Vin equals 0.Because the internal resistance of choke induction L1 is very little, signal VA is essentially the direct current signal that amplitude is VCCA, and VCCA is substantially equal to supply voltage VCC.And when Vin is greater than 0, signal VA is the AC signal that comprises DC component VCCA.According to the difference of bias voltage Vb, the first transistor M1 is in different working points.The ceiling voltage of the drain electrode of the first transistor M1 can arrive 2～4 times of VCC.This drain electrode withstand voltage that just requires the first transistor M1 is 2～4 times of supply voltage.。
On the basis of the power amplifier of the prior art shown in Fig. 1, a kind of scheme of the problem of withstand voltage of the solution the first transistor M1 having proposed is between choke induction L1 and power supply, to be connected in series a resistance.Due to the dividing potential drop of this series resistor, the DC component of the output signal VA of the first transistor M1 will be less than supply voltage VCC, thereby reduce the requirement of withstand voltage of the first transistor M1.Yet the voltage drop on series resistor is relevant to the size of the direct current flowing through in the first transistor M1.When supply voltage VCC declines, the DC component of the output signal VA of the first transistor M1 can be starkly lower than VCC/2.As a result, the first transistor M1 just likely enters linear zone in static, thereby makes power amplifier cisco unity malfunction.
Fig. 3 is the schematic block diagram of power amplifier according to an embodiment of the invention.Similar with the power amplifier according to prior art shown in Fig. 1, power amplifier of the present invention comprise choke induction L1 and the first transistor M1, the input coupling circuit being electrically connected to the grid of the first transistor M1 and be connected to the first transistor M1 and the intermediate node of choke induction L1 on output coupling circuit.This power amplifier also comprises the first resistance R 1 being connected in series between choke induction L1 and power supply as above, to reduce the requirement of withstand voltage of the first transistor M1.
Input coupling circuit for example comprises the first capacitor C 1 being connected between the input of power amplifier and the grid of the first transistor M1.Output coupling circuit can comprise be connected to intermediate node and the second capacitor C 2, the matched filtering circuit 101 between output of the first transistor M1 and choke induction L1 and be connected to output and ground between load matched resistance R L.The first capacitor C 1 and the second capacitor C 2 all play the effect that cuts off direct current.
Be with the difference according to the power amplifier of prior art shown in Fig. 1, power amplifier of the present invention comprises biasing circuit 102, to substitute biasing resistor R0.Biasing circuit 102 is connected in series between feeder ear and the grid of the first transistor M1.When work, biasing circuit 102 detects supply voltage VCC, and produce bias voltage Vb and be applied on the grid of the first transistor M1, for the working point of the first transistor M1 is set, make voltage drop in the first resistance R 1 be substantially equal to all the time half of supply voltage VCC.Also, the DC component of the output signal VA of the first transistor M1 approximates VCC/2 all the time.
Fig. 4 is the first example of power amplifier according to an embodiment of the invention.
As shown in Figure 4, biasing circuit 102 comprises the second resistance R 2 and the transistor seconds M2 being connected in series between feeder ear and ground.Intermediate node at the second resistance R 2 and transistor seconds M2 produces detection voltage VA2.By detecting voltage VA2, provide to the in-phase end of operational amplifier U1, and provide to the end of oppisite phase of operational amplifier U1 with reference to voltage VREF=VCC/2.The output of operational amplifier U1 is connected to the grid of transistor seconds M2 via the 3rd resistance R 3, via the 4th resistance R 4, be connected to the grid of the first transistor M1, to transistor seconds M2 and the first transistor M1, provide gate bias voltage respectively, so that its working point to be set.
The first transistor M1 and transistor seconds M2 are the transistors of identical conduction type.In an example, the first transistor M1 and transistor seconds M2 are N-type MOSFET.Select the resistance value of the first resistance R 1 and the second resistance R 2, make the product of the resistance value of the first resistance R 1 and the breadth length ratio of the first transistor M1, equal the product of the resistance value of the second resistance R 2 and the breadth length ratio of transistor seconds M2.
When work, biasing circuit is adjusted the working point of the first transistor M1 and transistor seconds M2 according to supply voltage VCC.The gate source voltage of the first transistor M1 is identical with the gate source voltage of transistor seconds M2.In the working range of transistor seconds M2, the feedback control loop providing by operational amplifier U1, can control the quiescent current in transistor seconds M2, thereby correspondingly controls the quiescent current of the first transistor M1.No matter how supply voltage VCC changes, and operational amplifier U1 all adjusts the first transistor M1 and transistor seconds M2 with feedback system, makes voltage drop in the first resistance R 1 and the second resistance R 2 be substantially equal to all the time half of supply voltage VCC.The DC component of the output signal VA of the first transistor M1 approximates VCC/2 all the time.
Fig. 5 is the second example of power amplifier according to an embodiment of the invention.
As shown in Figure 5, biasing circuit 102 comprises the second resistance R 2 and the transistor seconds M2 being connected in series between feeder ear and ground.The grid of transistor seconds M2 is connected to the grid of the first transistor M1 via the 3rd resistance R 3, and the grid of transistor seconds M2 is also connected to the intermediate node of the second resistance R 2 and transistor seconds M2.
The first transistor M1 and transistor seconds M2 are the transistors of identical conduction type.In an example, the first transistor M1 and transistor seconds M2 are N-type MOSFET.Select the resistance value of the first resistance R 1 and the second resistance R 2, make the product of the resistance value of the first resistance R 1 and the breadth length ratio of the first transistor M1, equal the resistance value of the second resistance R 2 and the breadth length ratio of transistor seconds M2 product 1/2.
When work, the grid of transistor seconds M1 is connected to supply voltage VCC via the second resistance R 2, thereby all the time in saturation condition.The gate source voltage of the first transistor M1 is identical with the gate source voltage of transistor seconds M2, thereby forms current mirror.The ratio I1/I2 of the quiescent current flowing through on the first transistor M1 and transistor seconds M2, equals the ratio K of two transistorized breadth length ratios, i.e. I1/I2=K.Because the source-drain voltage on transistor seconds M2 equals gate source voltage, therefore, the voltage at the second resistance R 2 two ends is approximately supply voltage VCC (wherein, having ignored the grid voltage on transistor seconds M2).The quiescent current flowing through on transistor seconds M2 is approximately I2=VCC/R2.Correspondingly, the quiescent current flowing through on the first transistor M1 is approximately I1=K*I2=K*VCC/R2.Thereby, the voltage drop VR1=I1*R1=K*VCC*R1/R2 in the first resistance R 1.
Due to the product of the resistance value of the first resistance R 1 and the breadth length ratio of the first transistor M1, equal the resistance value of the second resistance R 2 and the breadth length ratio of transistor seconds M2 product 1/2, therefore, the voltage drop VR1=VCC/2 in the first resistance R 1.No matter how supply voltage VCC changes, and power supply mirror is all adjusted the working point of the first transistor M2, makes voltage drop in the first resistance R 1 be substantially equal to all the time half of supply voltage VCC.The DC component of the output signal VA of the first transistor M1 approximates VCC/2 all the time.
Effect due to above-mentioned biasing circuit, in power amplifier of the present invention, the DC component of output signal VA that produces the first transistor M1 at the intermediate node of the first transistor M1 and choke induction L1 is relevant to supply voltage, and is substantially equal to all the time supply voltage VCC half.When power amplifier is worked under normal supply voltage, the voltage that the first transistor M1 bears can be reduced to original half.Along with supply voltage VCC is reduced to a half that is less than primary power voltage, the variation of supply voltage VCC still can be followed in the working point of the first transistor M1, thereby can guarantee the power output of power amplifier, and improves reliability and the linearity.
In the above-described embodiment, each transistorized conduction type has been described.Yet in alternative example, each in the first and second transistors can be contrary conduction type, correspondingly, needs to exchange the position of its source electrode and drain electrode in the circuit of Figure 4 and 5.
According to embodiments of the invention as described above, these embodiment do not have all details of detailed descriptionthe, and also not limiting this invention is only described specific embodiment.Obviously, according to above description, can make many modifications and variations.These embodiment are chosen and specifically described to this specification, is in order to explain better principle of the present invention and practical application, thereby under making, technical field technical staff can utilize the present invention and the modification on basis of the present invention to use well.Protection scope of the present invention should be as the criterion with the scope that the claims in the present invention were defined.
Claims (12)
1. a power amplifier, comprising:
The first resistance, choke induction and the first transistor that between power end and ground, are connected in series successively;
Be connected to the input coupling circuit between the input of power amplifier and the grid of the first transistor; And
Be connected to the output coupling circuit between the output of power amplifier and the first intermediate node of choke induction and the first transistor,
Wherein, described power amplifier also comprises the biasing circuit being connected with the grid of the first transistor, makes the working point of the first transistor follow the variation of supply voltage.
2. power amplifier according to claim 1, wherein, the working point of the first transistor is arranged so that half that is substantially equal to supply voltage in the DC component of the output signal of the first intermediate node.
3. power amplifier according to claim 1, wherein, described biasing circuit comprises:
Be connected in series in the second resistance and transistor seconds between feeder ear and ground, the second intermediate node between the second resistance and transistor seconds produces and detects voltage;
Be connected to the 3rd resistance of the grid of transistor seconds;
Be connected to the 4th resistance of the grid of the first transistor; And
Operational amplifier, its in-phase end receives and detects voltage, and its end of oppisite phase receives reference voltage, and its output is connected to the grid of transistor seconds via the 3rd resistance, and the grid that is connected to the first transistor via the 4th resistance,
Wherein, operational amplifier is adjusted the working point of the first transistor and transistor seconds with feedback system, makes the first resistance and the second ohmically voltage drop be substantially equal to all the time half of supply voltage.
4. power amplifier according to claim 3, wherein, half that described reference voltage is supply voltage.
5. power amplifier according to claim 3, wherein, the first transistor is identical with the conduction type of transistor seconds.
6. power amplifier according to claim 3, wherein, the product of the resistance value of the first resistance and the breadth length ratio of the first transistor, equals the product of the resistance value of the second resistance and the breadth length ratio of transistor seconds.
7. power amplifier according to claim 1, wherein, described biasing circuit comprises:
Be connected in series in the second resistance and transistor seconds between feeder ear and ground; And
Be connected to the 3rd resistance between the grid of the first transistor and the grid of transistor seconds,
Wherein, the grid of transistor seconds is also connected to the intermediate node of the second resistance and transistor seconds, and the first transistor and transistor seconds formation current mirror,
Current mirror is adjusted the working point of the first transistor, makes the first ohmically voltage drop be substantially equal to all the time half of supply voltage.
8. power amplifier according to claim 7, wherein, the first transistor is identical with the conduction type of transistor seconds.
9. power amplifier according to claim 7, wherein, the product of the resistance value of the first resistance and the breadth length ratio of the first transistor, equal the resistance value of the second resistance and the breadth length ratio of transistor seconds product 1/2.
10. power amplifier according to claim 1, wherein, described input coupling circuit comprises capacitance.
11. power amplifiers according to claim 1, wherein, described output coupling circuit comprises at least one in capacitance and load matched resistance.
12. power amplifiers according to claim 1, wherein, described output coupling circuit comprises matched filtering circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410188575.0A CN103944522B (en) | 2014-05-06 | 2014-05-06 | Power amplifier |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410188575.0A CN103944522B (en) | 2014-05-06 | 2014-05-06 | Power amplifier |
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| Publication Number | Publication Date |
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| CN103944522A true CN103944522A (en) | 2014-07-23 |
| CN103944522B CN103944522B (en) | 2018-05-11 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201410188575.0A Expired - Fee Related CN103944522B (en) | 2014-05-06 | 2014-05-06 | Power amplifier |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107404289A (en) * | 2016-05-19 | 2017-11-28 | 株式会社村田制作所 | Power amplifier module |
| CN107800390A (en) * | 2017-10-12 | 2018-03-13 | 宁波德晶元科技有限公司 | A kind of inverse E class power amplification circuits |
| CN113131879A (en) * | 2019-12-31 | 2021-07-16 | 圣邦微电子（北京）股份有限公司 | Amplifier for switching body bias and follower |
| CN113268103A (en) * | 2021-04-27 | 2021-08-17 | 上海萍生微电子科技有限公司 | Current mirror circuit and radio frequency module thereof |
| CN113411054A (en) * | 2021-08-19 | 2021-09-17 | 深圳飞骧科技股份有限公司 | Radio frequency amplifier and output 1dB compression point dynamic adjusting circuit thereof |
-
2014
- 2014-05-06 CN CN201410188575.0A patent/CN103944522B/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107404289A (en) * | 2016-05-19 | 2017-11-28 | 株式会社村田制作所 | Power amplifier module |
| CN107404289B (en) * | 2016-05-19 | 2021-02-19 | 株式会社村田制作所 | Power amplifying module |
| CN107800390A (en) * | 2017-10-12 | 2018-03-13 | 宁波德晶元科技有限公司 | A kind of inverse E class power amplification circuits |
| CN113131879A (en) * | 2019-12-31 | 2021-07-16 | 圣邦微电子（北京）股份有限公司 | Amplifier for switching body bias and follower |
| CN113131879B (en) * | 2019-12-31 | 2022-08-16 | 圣邦微电子（北京）股份有限公司 | Amplifier for switching body bias and follower |
| CN113268103A (en) * | 2021-04-27 | 2021-08-17 | 上海萍生微电子科技有限公司 | Current mirror circuit and radio frequency module thereof |
| CN113411054A (en) * | 2021-08-19 | 2021-09-17 | 深圳飞骧科技股份有限公司 | Radio frequency amplifier and output 1dB compression point dynamic adjusting circuit thereof |
| CN113411054B (en) * | 2021-08-19 | 2021-11-19 | 深圳飞骧科技股份有限公司 | Radio frequency amplifier and output 1dB compression point dynamic adjusting circuit thereof |
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| CN103944522B (en) | 2018-05-11 |
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