Highly efficient power amplifying device with many power modes
Technical field
The present invention relates to the power amplifier in a kind of mobile hand-held device (mobile handset).More particularly, the present invention relates to a kind of high efficiency many power modes power amplifier that has, it is suitable for correspondingly with multiple power output level coming amplifying power and need not using the by-pass switch circuit.
Background technology
Recently, along with the mobile hand-held device that is used for radio communication service is more and more littler and more and more lighter, use the air time of the mobile hand-held device of small size battery also to carry out a lot of research to prolongation.In the mobile hand-held device of routine, radio frequency (RF) power amplifier has consumed the major part of the electric weight that the mobile hand-held device total system consumed.Therefore, the poor efficiency of RF power amplifier has reduced the efficient of total system, thereby has reduced the air time.
For this reason, the most research of this area concentrates on the efficient that improves the RF power amplifier.Many power modes power amplifier is recently as one that carries out in the device that this research introduces with the result of the efficient that improves the RF power amplifier.
Many power modes power amplifier is configured to operate corresponding to required situation its power stage, and operates with several operator schemes corresponding to the power output level.Usually, the by-pass switch circuit is used for this operation of many power modes power amplifier.
Low if desired power output is adjusted into the path of power delivery so and walks around power stage.On the contrary, high-output power if desired, the path with power delivery is adjusted into by power stage so that high-output power is provided so.Use is many power modes power amplifier of the routine of execution pattern conversion according to required power output level and optionally, DC (direct current) power consumption in the time of can being reduced in the signal of the low power output of transmission.
But, in order to move many power modes power amplifier, one the power stage of tackling in the power stage of a plurality of mutual series connection of surpassing is switched, and needs to surpass one by-pass switch circuit and be used to control the complex logic control circuit of by-pass switch circuit to be used for handover operation.
The power loss that is caused by the handover operation of by-pass switch circuit makes power output reduce, and the reduction of power output makes the efficient of many power modes power amplifier reduce.In addition, exist other problem to be that adjacent channel power is than (ACPR) variation.In addition, because the by-pass switch circuit complex logic control circuit that increase extra with being used to control the by-pass switch circuit makes the size of whole system become bigger.Therefore, consider the trend of undersized mobile hand-held device, many power modes power amplifier of prior art is considered to fall behind, and the size of the expansion of whole system is disadvantageous in price competition.
Many power modes power amplifier to the use by-pass switch circuit of prior art is elaborated below with reference to the accompanying drawings.
Fig. 1 shows many power modes power amplifier of the use by-pass switch circuit of prior art.Many power modes power amplifier as shown in Figure 1 is configured to use 3 by-pass switch circuit.
If power amplifier is operated with high-power mode, first switch 31 and second switch 32 are all closed and the 3rd switch 33 disconnects so, feasiblely like this comprise that the output of the driver 10 of impedance matching unit is imported in the power stage 22.On the contrary, if power amplifier is operated with low-power mode, first switch 31 and second switch 32 all disconnect and the 3rd switch closure so, thereby make the output of the driver 10 comprise impedance matching unit walk around power stage 22.
Because the power amplifier of many power modes as shown in Figure 1 uses 3 by-pass switch circuit, so the degrees of freedom in the structure of many power modes power amplifier increase.But simultaneously, it has that the whole system size increases and because the shortcoming of the power loss increase of the whole system that the power loss of by-pass switch circuit causes.Especially the power loss of second switch 32 that is connected to the output of power stage has had a strong impact on the operating efficiency and the linearity under the high-power mode, therefore should use by-pass switch circuit, and use the necessity of by-pass switch circuit to need expensive with high power capacity and good loss characteristic.
Fig. 2 shows many power modes power amplifier of the other by-pass switch circuit of the use of prior art.Many power modes power amplifier as shown in Figure 2 is configured to not use tandem tap and is to use branch switch (shunt switch).
Under high-power mode, the branch switch ground connection of the second by-pass switch circuit 49, and with the 3rd impedance transformer 48 operations as impedance matching unit.First impedance transformer 47 will comprise that the load transfer of the output stage of the second by-pass switch circuit 49 and the 3rd impedance transformer 48 is to make the optimum impedance Zopt of output maximum of power stage 45.The switch of the first by-pass switch circuit 44 is connected to the input 43 of power stage.
Under low-power mode, the second by-pass switch circuit 49 is connected to the output of second impedance transformer, and first impedance transformer 47 forms impedance matching unit with the impedance that the output impedance by the power stage 45 of will close of second impedance transformer 46 and the 3rd impedance transformer 48 is converted to j50 ohm.The switch of the first by-pass switch circuit 44 is connected to the input of second impedance transformer 46, forms bypass with this.The first by-pass switch circuit 44 can be configured to use two diode switches, and the second by-pass switch circuit 49 can be configured to use a diode switch along separate routes.
Because power amplifier as shown in Figure 2 should use at least 3 switches, so owing to the loss of switch oneself makes degradation, and owing to the increase of power amplifier size makes the price competition variation.
Fig. 3 a shows many power modes power amplifier of the prior art of using the by-pass switch circuit, and its switching circuit is connected to the output of λ/4 bypass transmission line.Many power modes power amplifier shown in Fig. 3 a comprises carrier amplifier 51 and has the bypass that realizes by by the by-pass switch circuit that uses λ/4 bypass transmission line 52 and branch switch 53 configurations.
Under high-power mode, branch switch 53 ground connection of by-pass switch circuit, and the by-pass switch circuit that comprises branch switch 53 by being connected to λ/4 bypass transmission line 52 as open branch line (open stub) operation.
Under low-power mode, the branch switch 53 of by-pass switch circuit is connected to the output of carrier amplifier 51, and with λ/4 bypass transmission line 52 as bypass operation.
Fig. 3 b shows many power modes power amplifier of the prior art of using the by-pass switch circuit, and its switching circuit is connected to the input of λ/4 bypass transmission line.
Difference between many power modes power amplifier shown in many power modes power amplifier shown in Fig. 3 b and Fig. 3 a only is the order of λ/4 bypass transmission line and by-pass switch circuit.
Because the many power modes power amplifier shown in Fig. 3 a and the 3b includes only a by-pass switch circuit, so its advantage is that the size of whole system is less.But simultaneously, shortcoming is owing to using λ/4 bypass transmission line to make limited bandwidth.
Fig. 4 shows many power modes power amplifier of the prior art of using other by-pass switch circuit.
Q3 (65) is a carrier amplifier, and Q2 (62) is an operational amplifier.Tandem tap 66 comprises two diode connected in parallel, and the anode of diode is connected to the Vcc of carrier amplifier.
Under high-power mode, Q1 (68) ends and tandem tap 66 disconnects.Therefore the output of Q2 (62) is imported among the Q3 (65), and first impedance matching unit 63 is the impedance matching units that input impedance are converted to 15 ohmages.
Under low-power mode, the base bias of Q3 (65) is closed and Q1 (68) conducting, thereby makes switch 66 closures.Second impedance matching unit 64 is the impedance matching units that load impedance are converted to 25 ohmages.Second impedance matching unit 64 has the little impedance of input impedance than Q3 (65) when switch 66 closures, and has the big impedance of input impedance than Q3 (65) when switch 66 disconnects.Therefore, second impedance matching unit 64 is as bypass operation.
Summary of the invention
One object of the present invention is to solve at least the problems referred to above of many power modes power amplifier of the prior art of using the by-pass switch circuit, and provide a kind of high efficiency many power modes power amplifier that has, connect to be incorporated on the path that is used to walk around power stage at the optimum place by the path that is used in the path of walking around power stage and is used to pass power stage and realize the optimum impedance converter, this many power modes power amplifier can need not to use the by-pass switch circuit and amplify the power of multiple level.
A kind of high efficiency many power modes power amplifier is provided, has comprised: driver is used for amplifying input power; First impedance matching unit, it is connected with driver; Second impedance matching unit, it is connected with first impedance matching unit; Power stage, it is connected with second impedance matching unit; The applied voltage control circuit, it is in parallel with power stage, be used for being applied to the voltage of power stage corresponding to first power mode and second power mode control, power stage is opened, wherein under second power mode, power stage is configured to receive by first impedance matching unit and second impedance matching unit and is driven the power that device amplifies, once more the power that amplifies once more of amplifying power and output; Impedance transformer is used for receiving the power that is driven the device amplification by first impedance matching unit under first power mode; The 3rd impedance matching unit, it is connected with power stage, is used for receiving under second power mode power that is amplified by power stage; And the 4th impedance matching unit, the power that is used for transmitting from the 3rd impedance matching unit or impedance transformer is sent to output stage.
Preferably, impedance transformer is in parallel with second impedance matching unit, power stage and the 3rd impedance matching unit, and under first power mode, impedance transformer is driven the power of device amplification and this power is outputed to the 4th impedance matching unit by the reception of first impedance matching unit.In addition, impedance transformer has the structure of band pass filter.
Preferably, the 3rd impedance matching unit prevents that the Power leakage that transmits by impedance transformer from arriving power stage.
Preferably, the 4th impedance matching unit receives the power that comes from impedance transformer under first power mode, and the 4th impedance matching unit receives the power that comes from the 3rd impedance matching unit under second power mode.
Preferably, the power path that is transmitted to the 4th impedance matching unit through first impedance matching unit will be by determining with comparing towards the observed impedance of impedance transformer from first impedance matching unit towards the observed impedance of power stage from first impedance matching unit.
Preferably, under second power mode, form interstage matched unit between driver and the power stage towards the observed impedance of impedance transformer with first impedance matching unit from first impedance matching unit.
Another kind of many power modes of high efficiency power amplifier is provided, comprises: driver is used to use variable gain amplifier to come the gain of amplification input signal changeably; Power stage is used for receiving by first impedance matching unit of connecting with driver and second impedance matching unit of connecting with first impedance matching unit and is driven the power that device amplifies, once more the power that amplifies once more of amplifying power and output; The applied voltage control unit, it is in parallel with power stage, is used to control the applied voltage corresponding to first power mode and second power mode; Impedance transformer is used for receiving the power that is driven the device amplification by first impedance matching unit according to the operation of applied voltage control circuit; The 3rd impedance matching unit, it is connected with power stage, is used for receiving the power that is amplified by power stage according to the operation of applied power control circuit; And the 4th impedance matching unit, it is connected with the 3rd impedance matching unit and connects with impedance transformer, is used for will being sent to output stage from the power that the 3rd impedance matching unit or impedance transformer transmit according to the operation of applied voltage control circuit.
Preferably, under second power mode, power stage is connected with second impedance matching unit, and power stage receives the power that is driven the device amplification and amplifies this power once more by second impedance matching unit.
Preferably, applied voltage control circuit Control Driver in case the gain that is input in the driver differently amplified according to first power mode and second power mode.The adjustment of applied voltage control circuit is applied to the voltage of power stage, and power stage is opened.
Preferably, impedance transformer is in parallel with second impedance matching unit, power stage and the 3rd impedance matching unit, under first power mode, impedance transformer is driven the power of device amplification and this power is outputed to the 4th impedance matching unit by the reception of first impedance matching unit.Impedance transformer has the structure of band pass filter.
Preferably, the 3rd impedance matching unit prevents that the Power leakage that transmits by impedance transformer from arriving power stage.
Preferably, the 4th impedance matching unit receives the power that comes from impedance transformer under first power mode, and the 4th impedance matching unit receives the power that comes from the 3rd impedance matching unit.
Preferably, the power path that is transmitted to the 4th impedance matching unit through the power of first impedance matching unit will be by determining with comparing towards the observed impedance of impedance transformer from first impedance matching unit towards the observed impedance of power stage from first impedance matching unit.
Preferably, under second power mode, form interstage matched unit between driver and the power stage towards the observed impedance of impedance transformer with first impedance matching unit from first impedance matching unit.
Brief description of drawings
Fig. 1 shows many power modes power amplifier of the prior art of using the by-pass switch circuit;
Fig. 2 shows many power modes power amplifier of the prior art of using other by-pass switch circuit;
Fig. 3 a shows many power modes power amplifier of the prior art of using the by-pass switch circuit, and its switching circuit is connected to the output of λ/4 bypass transmission line;
Fig. 3 b shows many power modes power amplifier of the prior art of using the by-pass switch circuit, and its switching circuit is connected to the input of λ/4 bypass transmission line;
Fig. 4 represents to use many power modes power amplifier of the prior art of other by-pass switch circuit;
Fig. 5 shows according to many power modes of the described high efficiency of preferred embodiment power amplifier of the present invention, and it has adopted does not have the power mode of by-pass switch circuit transformational structure;
Fig. 6 shows in detail many power modes of high efficiency power amplifier as shown in Figure 5, and being used to explain does not have the power mode of by-pass switch circuit transformational structure;
The curve chart of Fig. 7 a show with according to the high-power mode and the corresponding gain characteristic of low-power mode of a described many power modes power amplifier of preferred embodiment of the present invention;
The curve chart of Fig. 7 b shows and adds efficient (PAE) characteristic according to the high-power mode of a described many power modes power amplifier of preferred embodiment of the present invention and the corresponding power of low-power mode;
Fig. 8 shows according to many power modes of the described high efficiency of another preferred embodiment of the present invention power amplifier, and it has adopted does not have the power mode of by-pass switch circuit transformational structure;
Realize best mode of the present invention
To provide below with reference to accompanying drawing detailed description according to many power modes of the described high efficiency of the preferred embodiments of the invention power amplifier.Hereinafter, first power mode is called as low-power mode and second power mode is called as high-power mode.
Fig. 5 shows according to described employing of a preferred embodiment of the present invention does not have many power modes of high efficiency of the power mode of by-pass switch circuit transformational structure power amplifier.
Many power modes of high efficiency power amplifier as shown in Figure 5 comprises: driver 100 is used to amplify input power; Power stage 120, be used for receiving and be driven the power that device 100 amplifies by first impedance matching unit 130 of connecting and second impedance matching unit 140 of connecting with first impedance matching unit 130 with driver, and the power that amplified once more of amplifying power and output once more; Applied voltage control circuit 90, it is in parallel with power stage 120, is used for controlling applied voltage accordingly with low-power mode and high-power mode; Impedance transformer 170 is used for receiving the power that is driven device 100 amplifications according to the operation of applied voltage control circuit 90 by first impedance matching unit 130, and power is sent to the 4th impedance matching unit 160; The 3rd impedance matching unit 150, it is connected with power stage 120, and the power that is used for being amplified by power stage 120 is sent to the 4th power match unit 160; And the 4th impedance matching unit 160, it is connected with the 3rd impedance matching unit 150 and connects with impedance transformer 170, is used for will being sent to output stage 78 from the power of the 3rd impedance matching unit 150 or impedance transformer 170 transmission according to the operation of applied voltage control circuit 90.
90 utilizations of applied voltage control circuit and low-power mode and the corresponding external control signal input of high-power mode are adjusted the voltage that is applied to power stage 120.Under low-power mode, owing to power output is not to pass power stage 120 but obtain through best first impedance matching unit 130 and best impedance transformer 170,, applied voltage control circuit 90 is applied to the voltage of power stage 120 so that the transistor of power stage 120 is closed so adjusting.
On the contrary, because power output obtains through first impedance matching unit 130, second impedance matching unit 140 and power stage 120, so applied voltage control circuit 90 applies the voltage of the transistor operation that is suitable for power stage 120.
Driver 100 under the low-power mode amplifies input powers and first impedance matching unit 130 by the best is sent to impedance transformer 170 with the power that amplifies.On the contrary, the driver under the high-power mode 100 amplifies input power and by first impedance matching unit 130 of the best and the second best impedance matching unit 140 power that amplifies is sent to power stage 120.
Power stage 120 under the low-power mode is closed by applied voltage control circuit 90, and the power stage 120 under the high-power mode is amplified and is driven device 100 and amplifies and be input to signal in the power stage 120.
First impedance matching unit 130 is the circuit that are used for corresponding to the best of the optimum operation of low-power mode and high-power mode.First impedance matching unit 130 optionally will be driven the input power that device 100 amplifies and be sent to impedance transformer 170 or power stage 120 corresponding to operator scheme.
Second impedance matching unit 140 is the circuit that are used for corresponding to the best of the optimum operation of low-power mode and high-power mode.Second impedance matching unit 140 will be driven the power that device 100 amplifies and transmit by first impedance matching unit 130 and be sent to impedance transformer 170 under the low-power mode and be sent to power stage 120 under high-power mode.
Impedance transformer 170 is corresponding to low-power mode and high-power mode and the impedance inverter circuit of proper transformation impedance.Under low-power mode, impedance transformer 170 forms the path of walking around power stage 120, makes the output of driver 100 be sent to the output stage 78 of power amplifier.
Fig. 6 is expression many power modes of high efficiency power amplifier as shown in Figure 5 in detail, and being used to illustrate does not have the power mode of by-pass switch circuit transformational structure.
The power output of driver 100 arrives the joint 72 that is used for making the path corresponding to power mode to separate by first impedance matching unit 130.
Under low-power mode, power stage 120 is closed by the voltage that is applied by applied voltage control circuit 90, and from the input impedance Z of the observed power stage 120 of the angle of first impedance matching unit 130
INT-HRatio is from the observed input impedance Z that walks around the path of power stage 120 of the angle of first impedance matching unit 130
INT-LBig a lot.Therefore, be driven that device 100 amplifies and to be sent to the power of joint 72 optimised, thereby make that the quantity of power that is input in the impedance transformer 170 is more much bigger than the quantity of power that is input in the power stage 120.Power output is leaked into the power of power stage and sends output stage 78 to minimized by the 3rd impedance matching unit 150 and the 4th impedance matching unit 160.
Under high-power mode, power stage 120 is opened by the voltage that is applied by applied voltage control circuit 90, and from the input impedance Z of the observed power stage 120 of the angle of first impedance matching unit 130
INT-HRatio is from the observed input impedance Z that walks around the path of power stage 120 of the angle of first impedance matching unit 130
INT-LLittle.Therefore, be driven that device 100 amplifies and most of power of being sent to joint 72 is amplified by power stage 120 and leak into the power of impedance transformer 170 and be sent to the output stage 78 of power amplifier with minimized by the 3rd impedance matching unit 150 of the best and best the 4th impedance matching unit 160.
Under the high-power mode, the observed input impedance ZINT-L that walks around the path of power stage 120 forms the interstage matched unit with first impedance matching unit 130 between driver 100 and power stage 120 from the angle of first impedance matching unit 130, thereby makes the power output of driver 100 be sent to power stage 120 well.
The curve chart of Fig. 7 a show with according to the high-power mode and the corresponding gain characteristic of low-power mode of a described many power modes power amplifier of preferred embodiment of the present invention.
Under low-power mode, power stage 120 is closed by applied voltage control circuit 90, so that the output of driver 100 do not amplified by power stage 120, and makes the output of driver 100 be sent to output stage 78 by impedance transformer 170.Therefore, the gain characteristic in the time of can not obtaining by power stage 120 amplifications.But, can eliminate the DC power that power stage 120 consumes like this, thereby make that the PAE characteristic is outstanding.
On the contrary, under high-power mode, the output of driver 100 is amplified by power stage 120 and is arrived output stage 78, gain characteristic when making by power stage 120 amplifications like this is increased to the gain characteristic by the operation under the low-power mode, and the PAE characteristic depends on the power stage 120 that has the high-output power level usually.
Therefore, shown in Fig. 7 a, the gain characteristic under the low-power mode is relatively low and gain characteristic under the high-power mode is higher relatively.
The curve chart of Fig. 7 b shows and adds efficiency characteristic according to the high-power mode of a described many power modes power amplifier of preferred embodiment of the present invention and the corresponding power of low-power mode.
Shown in Fig. 7 a, because the DC power that is consumed by power stage 120 can be eliminated, so the PAE characteristic under the low-power mode is outstanding.Under high-power mode, the output of power stage 120 is sent to output stage 78 by the 3rd impedance matching unit 150 and the 4th impedance matching unit 160, and the 3rd impedance matching unit 150, the 4th impedance matching unit 160 and impedance transformer 170 do not use switch, therefore make the output of power stage 120 not be sent to output stage 78 with having loss, thereby make the PAE characteristic under the high-power mode outstanding.
Fig. 8 shows many power modes of the high efficiency power amplifier that does not have the power mode transformational structure of by-pass switch circuit according to the employing of another preferred embodiment of the present invention.
Employing according to another preferred embodiment of the present invention does not have many power modes of high efficiency power amplifier of the power mode transformational structure of by-pass switch circuit to comprise: driver 210 is used to use variable gain amplifier to come the gain of amplification input signal changeably; Power stage 220, be used for receiving the power that is driven device 210 amplifications by first impedance matching unit 230 of connecting with driver 210 and second impedance matching unit 240 of connecting with first impedance matching unit 230, amplifying power is also exported the power that amplifies once more once more; Applied voltage control unit 190, it is in parallel with power stage 220, is used to control the applied voltage corresponding to low-power mode and high-power mode; Impedance transformer 270 is used for receiving the power that is driven device 210 amplifications according to the operation of applied voltage control circuit 190 by first impedance matching unit 230; The 3rd impedance matching unit 250, it is connected with power stage 220, is used for receiving the power that is amplified by power stage 220 according to the operation of applied power control circuit; And the 4th impedance matching unit 260, it is connected with the 3rd impedance matching unit 250 and connects with impedance transformer 270, is used for will being sent to output stage 178 from the power of the 3rd impedance matching unit 250 or impedance transformer 270 transmission according to the operation of applied voltage control circuit.
Applied voltage control circuit 190 Control Driver so as the signal gain that is input in the driver differently amplified according to low-power mode and high-power mode.The corresponding external control signal input of utilization of applied voltage control circuit and low-power mode and high-power mode is adjusted the voltage that is applied to power stage 220.Because power output is not through power stage 220 but obtain through best first impedance matching unit 230 and best impedance transformer 270 under low-power mode, thus the adjustment of applied voltage control circuit be applied to power stage 220 voltage so that the transistor of power stage 220 close.
On the contrary, because power output obtains through first impedance matching unit 230, second impedance matching unit 240 and power stage 220, so applied voltage control circuit 190 applies the voltage of the transistor operation that is suitable for power stage 220.
The gain that variable gain amplifier amplifies the signal of importing by the input 180 of power amplifier changeably according to the operation of applied voltage control circuit 190, and the gain that will amplify is supplied to first impedance matching unit 230, power stage 220 and impedance transformer 270.Variable gain amplifier not only plays the function of driver but also plays the function of linear circuit, so just makes the efficient of circuit and the linearity be optimized.In addition, can make corresponding adjustment to the discontinuous gain characteristic of the power amplifier shown in Fig. 7 a according to purposes.
Power stage 220 under the low-power mode is closed by applied voltage control circuit 190, and device 210 amplifies and the signal that is input in the power stage 220 amplifies and 220 pairs of the power stages under the high-power mode are driven.
First impedance matching unit 230 is the circuit that are used for corresponding to the best of the optimum operation of low-power mode and high-power mode.First impedance matching unit 230 optionally will be driven the input power that device 210 amplifies and be sent to impedance transformer 270 or power stage 220 corresponding to operator scheme.
Second impedance matching unit 240 is the circuit that are used for corresponding to the best of the optimal operations of low-power mode and high-power mode.Second impedance matching unit 240 will be amplified by variable gain amplifier and the power that transmits by first impedance matching unit 230 is sent to impedance transformer 270 and is sent to power stage 220 under high-power mode under low-power mode.
Impedance transformer 270 is corresponding to low-power mode and high-power mode and the impedance inverter circuit of proper transformation impedance.Under low-power mode, impedance transformer 270 forms walks around the path of power stage 220, thereby makes the output of driver 210 be sent to the output stage 178 of power amplifier.
Be not limited to these preferred embodiments according to many power modes power amplifier of the present invention, but can realize by multiple modification not breaking away from by those skilled in the art by the disclosed scope and spirit of the present invention of appended claim.
Industrial applicability
According to many power modes power amplifier of the present invention in the situation of not using the by-pass switch circuit Be down the power of scalable multiple level, thereby so that many power modes power of the prior art put Loss, the increase of power amplifier size, valency because using the by-pass switch circuit to cause in the big device The problems such as lattice competition variation can be resolved. In addition, put according to many power modes power of the present invention Big device has reduced affects the DC of battery life power consumption practically under low-power mode, thereby makes The PAE performance of power amplifier can improve, and make and be equipped with according to many power mould of the present invention The air time of the mobile hand-held device of formula power amplifier can prolong.
In addition, adopt variable gain amplifier as the present invention of driver many merits with prior art The loss of rate mode power amplifier under high-power mode drops to minimum, like this so that the high power mould PAE characteristic under the formula can improve, and can solve the bad linearity problems under the high-power mode. In addition, can realize being equipped with the ambulatory handheld according to many power modes power amplifier of the present invention to establish The raising of standby speech quality and be equipped with according to many power modes power amplifier of the present invention Reducing of the size of handheld device.