CN109889163B - Doherty power amplifier based on transformer - Google Patents
Doherty power amplifier based on transformer Download PDFInfo
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- CN109889163B CN109889163B CN201910144421.4A CN201910144421A CN109889163B CN 109889163 B CN109889163 B CN 109889163B CN 201910144421 A CN201910144421 A CN 201910144421A CN 109889163 B CN109889163 B CN 109889163B
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention discloses a Doherty power amplifier based on a transformer, which comprises a main power amplifier and an auxiliary power amplifier which are connected in parallel, wherein the output end of the main power amplifier is connected with a primary coil of a main output transformer, the output end of the auxiliary power amplifier is connected with the primary coil of the auxiliary output transformer, and a secondary coil of the main output transformer is connected with a secondary coil of the auxiliary output transformer and forms an output end of a radio frequency output signal; the main output transformer is connected with the center tap of the primary coil of the auxiliary output transformer and forms a power supply voltage connecting end, and the power supply voltage connecting end is connected to a plurality of power supply voltages with different sizes through a plurality of selection switches; the magnitude of the power supply voltage corresponds to the power back-off interval of the Doherty power amplifier and increases the efficiency of the Doherty power amplifier in the corresponding power back-off interval. The invention can optimize the efficiency of different power back-off intervals.
Description
Technical Field
The present invention relates to a semiconductor integrated circuit, and more particularly, to a Doherty (Doherty) Power Amplifier (PA) based on a transformer.
Background
In the advanced wireless standards today, an orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) modulation mode is adopted to increase the data rate, but in the modulation mode, when a plurality of waves are multiplexed, waves with the same initial phase are easy to be overlapped, so that the instantaneous power is increased, the peak-to-average ratio (PAPR) is very large, the dynamic range of a power amplifier is increased by a larger PAPR, and the nonlinearity of the PA is deteriorated. In order to improve the effect of PAPR on the nonlinearity of PA, a Power Back-off method is generally adopted for setting, the Power Back-off method is to Back-off the input Power of the Power amplifier by 6-10 decibels from a 1dB compression point, the 1dB compression point is equivalent to the critical point of the linear region and the nonlinearity region of the Power amplifier, and the Power amplifier works at a level far smaller than the 1dB compression point after Back-off, so that the Power amplifier is far away from the saturation region and enters the linear working region, thereby improving the third-order intermodulation coefficient of the Power amplifier. However, after the power is backed, the power amplifier is very inefficient in the power back-off interval, thereby reducing the average efficiency.
In the existing method, the Doherty PA is adopted to improve the efficiency of a certain power back-off interval, so that the flat efficiency is improved. The Doherty PA adopts an active load modulation technique, and dynamically changes the impedance seen by the output ends of the main power amplifier and the secondary power amplifier along with the change of the input power.
As shown in fig. 1, a schematic diagram of an existing Doherty PA, which includes a Main (Main) power amplifier 101 and an auxiliary (aux.) power amplifier 102.
The main power amplifier 101 operates in class AB and the auxiliary power amplifier 102 operates in class C. The auxiliary power amplifier 102 is normally turned off before the main power amplifier 101 is saturated, when only the main power amplifier 101 is operating; the auxiliary power amplifier 102 is turned on when the main power amplifier 101 is saturated, and the output signal is a superimposed signal of the output signals of the main power amplifier 101 and the auxiliary power amplifier 102.
The rf input signal RFIN is input to the input end of the main power amplifier 101, and a 1/4 wavelength line (λ/4 line) 103a is further connected to the output end of the main power amplifier 101, and then the rf output signal RFOUT is output, where the 1/4 wavelength line 103a is used to implement impedance transformation with different signal intensities.
A 1/4 wavelength line 103b is connected to the input of the auxiliary power amplifier 102 for phase matching the main power amplifier 101 path and the auxiliary power amplifier 102 path.
As shown in fig. 2, the graph of the input power and the output power of the structure shown in fig. 1 is shown with the abscissa being the normalized input power (Normalized Input Power), the ordinate being the normalized output power (Normalized Output Power), the graph 201 being the graph of the input power and the output power corresponding to the main power amplifier 101, the graph 202 being the graph of the input power and the output power corresponding to the auxiliary power amplifier 102, the graph 203 being the graph of the input power and the output power of the entire Doherty PA, and the graph 203 being the superposition of the graphs 201 and 202. As can be seen, curve 201 saturates and linearly deteriorates as the input power increases; the curve 203 formed by overlapping the curve 201 and the curve 202 has better linearity.
As shown in fig. 3, there are curves of voltage and impedance of the main PA101 and the auxiliary PA102 of the structure shown in fig. 1 and efficiency curves of the entire Doherty PA; curve 204 is the curve of the output voltage (Vmain) of the main PA101 and the normalized output voltage (Normalized Output Voltage) of the Doherty PA, curve 205 is the curve of the output voltage (vaux.) of the auxiliary PA102 and the normalized output voltage of the Doherty PA, curve 206 is the curve of the impedance (Zmain) seen at the output of the main PA101 and the normalized output voltage of the Doherty PA, and curve 207 is the curve of the impedance (zaux.) seen at the output of the auxiliary PA102 and the normalized output voltage of the Doherty PA.
The abscissas of curves 204, 205, 206, 207 and 208 are all normalized output voltages of the Doherty PA, the ordinates of curves 204, 205, 206 and 207 are normalized voltages and impedances (Normalized Voltage and Impedance) on the right, and the ordinates of curve 208 are normalized efficiencies on the right.
As can be seen from curve 204, when the input voltage is less than half the maximum input voltage, between 0.0 and 0.5 corresponding to the normalized output voltage, only the main PA101 is operating; and when the input voltage is exactly half the maximum input voltage, the main PA101 reaches a saturated output, at which point the efficiency reaches a maximum, i.e. corresponds to the highest point in the curve 208. Meanwhile, the impedance Zmain corresponding to the curve 206 is a maximum value when the input voltage is less than half of the maximum input voltage.
As can be seen from curve 203, the auxiliary PA102 starts to operate as the input voltage continues to rise, i.e., between 0.5 and 1.0 for the corresponding normalized output voltage; when the auxiliary PA102 begins to operate, the magnitude of the impedance Zmain is actively adjusted, as can be seen from curve 206, which decreases; likewise, the main PA101 may also actively adjust the impedance zaux corresponding to the auxiliary PA102, and as can be seen from curve 207, the impedance zaux may decrease. In case Vmain remains unchanged and Zmain becomes smaller, the output power of the main PA101 increases.
However, the efficiency will remain high between 0.5 and 1.0 for the normalized output voltage, and will be at a maximum when the input voltage reaches a maximum input voltage, i.e., the normalized output voltage is 1.0, as shown by curve 208.
Therefore, as can be seen from curve 208, the Doherty PA increases the efficiency of the power backoff interval.
As shown in fig. 4, a comparison curve of the efficiency of the power backoff interval of the conventional Doherty PA is shown; curve 209 is a plot of the efficiency and output power Back-off value (Output Power Back-off) of an existing ideal Doherty PA with a 6dB power Back-off value, which corresponds to Ideal Doherty with dB Back-off depicted in fig. 4; curve 210 is a plot of the efficiency and output power back-off value of an existing Ideal Class B power amplifier, which corresponds to Ideal Class-B described in fig. 4.
The abscissas of curves 209, 210, 211, and 212 are output power back-off values, the abscissas of curves 209 and 210 are normalized efficiencies on the right side, and the ordinates of curves 211 and 212 are normalized probability densities on the left side.
As can be seen from curves 209 and 210, curve 209 corresponds to a 6dB shift to the left, i.e. a 6dB back-off, based on curve 210, and the efficiency remains large after saturation of the main PA. The use of Doherty PA can improve efficiency.
As can be seen from the curves 211 and 212, the systems corresponding to LTE and ieee802.11b mainly operate in the power backoff interval, and the Doherty PA improves the efficiency of the power backoff interval, so that the average efficiency can be improved.
In recent years, transformer-based Doherty power amplifiers have emerged that operate in a similar manner to the classical Doherty PA shown in fig. 1. Existing transformer-based Doherty PAs can provide higher efficiency in the 6dB power back-off interval, but the efficiency remains to be optimized in the deeper 12dB power back-off interval.
Disclosure of Invention
The invention aims to solve the technical problem of providing a Doherty power amplifier based on a transformer, which can optimize the efficiency of different power backspacing intervals.
In order to solve the technical problem, the Doherty power amplifier based on the transformer comprises a main power amplifier and an auxiliary power amplifier which are connected in parallel, wherein the output end of the main power amplifier is connected with a primary coil of a main output transformer, the output end of the auxiliary power amplifier is connected with a primary coil of an auxiliary output transformer, and a secondary coil of the main output transformer is connected with a secondary coil of the auxiliary output transformer and is provided with an output end of a radio frequency output signal.
The center tap of the primary coil of the main output transformer is connected with the center tap of the primary coil of the auxiliary output transformer and forms a power supply voltage connecting end, and the power supply voltage connecting end is connected to a plurality of power supply voltages with different sizes through a plurality of selection switches; the power supply voltage corresponds to a power back-off interval of the Doherty power amplifier, the efficiency of the Doherty power amplifier in the corresponding power back-off interval is increased, and the larger the power back-off value of the power back-off interval of the Doherty power amplifier is, the smaller the power supply voltage is; conversely, the smaller the power back-off value of the power back-off section of the Doherty power amplifier, the larger the power supply voltage.
In a further improvement, the power supply voltage includes 2 power supply voltages, namely a first voltage value and a second voltage value.
A further improvement is that the first voltage value is 2 times the second voltage value.
The further improvement is that the power back-off interval corresponding to the first voltage value is back-off 0 dB-12 dB, and the power back-off interval corresponding to the second voltage value is back-off 12dB or more.
The further improvement is that the selection switch adopts a PMOS tube.
In a further improvement, the secondary coil of the main output transformer is connected in series with the secondary coil of the auxiliary output transformer, and the first end of the secondary coil of the main output transformer is an output end of the radio frequency output signal.
The second end of the secondary coil of the main output transformer is connected with the first end of the secondary coil of the auxiliary output transformer.
The second end of the secondary winding of the auxiliary output transformer is grounded.
A further improvement is that a capacitor is connected between the first end of the secondary winding of the main output transformer and the second end of the secondary winding of the auxiliary output transformer.
A further improvement is that a bypass network circuit is connected between the supply voltage connection and ground.
A further improvement is that the bypass network circuit is a circuit formed by connecting a plurality of series circuits formed by connecting resistors and capacitors in parallel.
The Doherty power amplifier further comprises a driving amplifier, wherein the input end of the driving amplifier is connected with a radio frequency input signal, and the output end of the driving amplifier is connected with the input end of the main power amplifier and the input end of the auxiliary power amplifier.
A further improvement is that the main power amplifier operates in class AB and the auxiliary power amplifier operates in class C.
A further improvement is that the radio frequency input signal is connected to the input of the driver amplifier via an input transformer.
A further improvement is that the main power amplifier comprises a cascode amplifier formed by connecting two NMOS transistors.
The auxiliary power amplifier comprises a common-source common-gate amplifier formed by connecting two NMOS (N-channel metal oxide semiconductor) tubes.
A further improvement is that the radio frequency input signal is a differential signal.
The main power amplifier is of a differential structure formed by connecting two groups of symmetrical common-source and common-gate amplifiers.
The auxiliary power amplifier is of a differential structure formed by connecting two groups of symmetrical common-source and common-gate amplifiers.
The main power amplifier is characterized in that two first resistors with the same size are connected in series between two differential input ends of the main power amplifier, and bias voltages enabling two groups of common-source common-gate amplifiers of the main power amplifier to work in class AB are added at the connection part of the two first resistors.
Two second resistors with the same size are connected in series between two differential input ends of the auxiliary power amplifier, and bias voltages enabling two groups of common-source common-gate amplifiers of the auxiliary power amplifier to work in class C are added at the connection position of the two second resistors.
The power supply voltage of the main power amplifier and the auxiliary power amplifier is set according to the power back-off value of the power back-off interval of the Doherty power amplifier, and when the power back-off value of the power back-off interval is increased, the power supply voltage can be reduced, so that the efficiency of the main power amplifier can be improved, the efficiency of the whole Doherty power amplifier can be improved, and the main power amplifier can reach a saturated output state again and the efficiency of the main power amplifier can be maximized in the power back-off interval with a larger power back-off value.
Drawings
The invention is described in further detail below with reference to the attached drawings and detailed description:
fig. 1 is a schematic diagram of the structure of a conventional Doherty PA;
FIG. 2 is a graph of input power and output power for the configuration of FIG. 1;
FIG. 3 is a plot of voltage and impedance of the main and auxiliary PAs of the configuration shown in FIG. 1 and an efficiency plot of the overall Doherty PA;
fig. 4 is a comparison curve of the efficiency of the power backoff interval of the conventional Doherty PA;
fig. 5 is a schematic diagram of the structure of a prior art transformer-based Doherty PA;
fig. 6 is a schematic diagram of a Doherty PA based on a transformer according to an embodiment of the invention;
fig. 7 is a schematic diagram of a Doherty PA based transformer in accordance with a preferred embodiment of the present invention;
fig. 8 is a graph comparing the power backoff interval efficiency of the Doherty PA and the prior art circuit according to the preferred embodiment of the present invention;
fig. 9 is a graph of a comparison of the power backoff interval efficiency of fig. 8 plus a probability density curve of LTE and IEEE802.11 b.
Detailed Description
Existing transformer-based Doherty PA:
as shown in fig. 5, a schematic diagram of a conventional transformer-based Doherty PA is shown, and the conventional transformer-based Doherty power amplifier includes a driver amplifier 301, a main power amplifier 302, and an auxiliary power amplifier 303.
The output of the driver amplifier 301 is connected to the input of the main power amplifier 302 and to the input of the auxiliary power amplifier 303, the input of the driver amplifier 301 is connected to a radio frequency input signal RFIN,
the main power amplifier 302 operates in class AB and the auxiliary power amplifier 303 operates in class C.
The radio frequency input signal RFIN is connected to the input of the driver amplifier 301 via an input transformer T101. The input end of the input transformer T101 is connected with a capacitor C101, and the output end is connected with a capacitor C102.
The output of the main power amplifier 302 outputs the radio frequency output signal RFOUT through a main output transformer T102. The input end of the main output transformer T102 is connected with a capacitor C103.
The output terminal of the auxiliary power amplifier 303 outputs the radio frequency output signal RFOUT through an auxiliary output transformer T103. The input end of the auxiliary output transformer T103 is connected with a capacitor C104.
The secondary windings of the main output transformer T102 and the auxiliary output transformer T103 have two interfaces corresponding to two output ends, and in fig. 5, the secondary windings of the main output transformer T102 and the auxiliary output transformer T103 are connected in a series structure, specifically: one port of the output end of the main output transformer T102 is connected with one port of the output end of the auxiliary output transformer T103, the other port of the output end of the main output transformer T102 is the output end of the radio frequency output signal RFOUT, the other port of the output end of the auxiliary output transformer T103 is grounded, and a capacitor C105 is connected between the other port of the output end of the main output transformer T102 and the other port of the output end of the auxiliary output transformer T103.
The existing transformer-based Doherty PA shown in fig. 5 is a new structure that has emerged in recent years in a similar manner to the classical Doherty PA shown in fig. 1. Existing transformer-based Doherty PAs can provide higher efficiency in the 6dB power back-off interval, but the efficiency remains to be optimized in the deeper 12dB power back-off interval.
The embodiment of the invention is based on the Doherty PA of the transformer:
as shown in fig. 6, a schematic diagram of a Doherty PA based on a transformer according to an embodiment of the present invention includes a main power amplifier 2 and an auxiliary power amplifier 3 connected in parallel, where an output end of the main power amplifier 2 and a main output transformer T 2 Is connected to the primary winding of the auxiliary power amplifier 3, the output of the auxiliary power amplifier 3 and the auxiliary output transformer T 3 Is connected with the primary winding of the main output transformer T 2 And said auxiliary output transformer T 3 Is connected to the secondary winding of the transformer and forms an output for the radiofrequency output signal RFOUT.
The main output transformer T 2 Center tap of primary winding of (c) and said auxiliary output transformer T 3 The center taps of the primary coils of (a) are connected and form a power supply voltage connection terminal, the power supply voltage connection terminal is connected to a plurality of power supply voltages with different magnitudes through a plurality of selection switches, the selection switches are shown as a dotted line box 4, the power supply voltages are shown as a dotted line box 5, 2 power supply voltages are shown in fig. 6, and are respectively indicated by VDD and VDD/2; the power supply voltage corresponds to a power back-off interval of the Doherty power amplifier, the efficiency of the Doherty power amplifier in the corresponding power back-off interval is increased, and the larger the power back-off value of the power back-off interval of the Doherty power amplifier is, the smaller the power supply voltage is; conversely, the smaller the power back-off value of the power back-off section of the Doherty power amplifier, the larger the power supply voltage.
In the embodiment of the invention, the power supply voltage includes 2 power supply voltages, which are respectively a first voltage value and a second voltage value. According to the structure of the embodiment of the invention, the power supply voltage can be expanded to be more than 2 according to practical application requirements.
The first voltage value is 2 times the second voltage value. In fig. 6, the first voltage value corresponds to the voltage value of the power supply voltage VDD, and the second voltage value corresponds to the voltage value of the power supply voltage VDD/2.
The power back-off interval corresponding to the first voltage value is back-off 0 dB-12 dB, and the power back-off interval corresponding to the second voltage value is back-off 12dB or more.
The main output transformer T 2 And said auxiliary output transformer T 3 The secondary coils of the coils are connected in series, and the series structure is as follows:
the main output transformer T 2 The first end of the secondary winding of (a) is the output end of the radio frequency output signal RFOUT.
The main output transformer T 2 Is connected to the auxiliary output transformer T at the second end of the secondary winding 3 Is provided for the first end of the secondary winding.
The auxiliary output transformer T 3 The second end of the secondary winding of (2) is grounded.
The main output transformer T 2 And said auxiliary output transformer T 3 A capacitor is connected between the second ends of the secondary windings.
A bypass network circuit 6 is connected between the supply voltage connection and ground.
The Doherty power amplifier further comprises a driving amplifier 1, wherein an input end of the driving amplifier 1 is connected with a radio frequency input signal RFIN, and an output end of the driving amplifier 1 is connected with an input end of the corresponding main power amplifier 2 and an input end of the auxiliary power amplifier 3.
The main power amplifier 2 operates in class AB and the auxiliary power amplifier 3 operates in class C.
The radio frequency input signal RFIN passes through the input transformer T 1 Is connected to the input of the driver amplifier 1.
The embodiment of the invention sets the power supply voltage of the main power amplifier 2 and the auxiliary power amplifier 3 according to the power back-off value of the power back-off interval of the Doherty power amplifier, and can reduce the power supply voltage when the power back-off value of the power back-off interval is increased, thereby improving the efficiency of the main power amplifier 2 and the efficiency of the whole Doherty power amplifier, wherein the main power amplifier 2 can reach the saturated output state and the maximum efficiency in the power back-off interval with larger power back-off value.
The preferred embodiment of the invention is based on the Doherty PA of the transformer:
as shown in fig. 7, which is a schematic diagram of a Doherty PA based on a transformer according to a preferred embodiment of the present invention, the structure shown in fig. 7 is further improved on the basis of the structure shown in fig. 6, and in the preferred embodiment of the present invention:
the selection switch adopts a PMOS tube, such as the PMOS tube MP in FIG. 7 1 And MP 2 。
The bypass network circuit 6 is a circuit formed by connecting a plurality of series circuits formed by connecting resistors and capacitors in parallel, such as resistor R in FIG. 7 1 、R 2 、R 3 And R is 4 And a capacitor C connected in series with the corresponding resistor 9 、C 6 、C 7 And C 8 。
The main power amplifier 2 comprises a common-source common-gate amplifier formed by connecting two NMOS tubes.
The auxiliary power amplifier 3 comprises a common-source common-gate amplifier formed by connecting two NMOS transistors.
The radio frequency input signal RFIN is a differential signal.
The main power amplifier 2 is a differential structure formed by connecting two groups of symmetrical cascode amplifiers, and the two groups of cascode amplifiers respectively correspond to the NMOS tube MN 5 And MN (Mobile node) 9 Structure formed by connection and NMOS tube MN 6 And MN (Mobile node) 10 And (3) connecting to form a structure.
The auxiliary power amplifier 3 is of a differential structure formed by connecting two groups of symmetrical cascode amplifiers. Two groups of cascode amplifiers are respectively pairedCorresponding to NMOS transistor MN 7 And MN (Mobile node) 11 Structure formed by connection and NMOS tube MN 8 And MN (Mobile node) 12 And (3) connecting to form a structure.
The driving amplifier 1 is of a differential structure formed by connecting two groups of symmetrical common-source and common-gate amplifiers. The common-source common-gate amplifier corresponding to the driving amplifier 1 is formed by connecting two NMOS tubes, and the two groups of common-source common-gate amplifiers of the driving amplifier 1 respectively correspond to the NMOS tubes MN 1 And MN (Mobile node) 3 Structure formed by connection and NMOS tube MN 2 And MN (Mobile node) 4 And (3) connecting to form a structure.
Common-gate connected NMOS tube MN in the common-source common-gate amplifier of the driving amplifier 1 3 And MN (Mobile node) 4 Is connected with a corresponding bias voltage V B2 And bias voltage V B2 Through corresponding resistor R B Is connected to NMOS transistor MN 3 And MN (Mobile node) 4 Is formed on the substrate. R is R B The representation represents the resistance for biasing.
A first inductance L is connected between two differential output ends of the driving amplifier 1 1 The first inductance L 1 Is connected with the first power supply voltage V DDL 。
Two equal first resistors are connected in series between two differential input ends of the main power amplifier 2, and a bias voltage V for enabling two groups of the common-source common-gate amplifiers of the main power amplifier 2 to work in class AB is added at the connection part of the two first resistors B_AB . In FIG. 7, R is used for both first resistors B The representation represents the resistance used for biasing.
Two second resistors with equal size are connected in series between two differential input ends of the auxiliary power amplifier 3, and bias voltage V for enabling two groups of common-source common-gate amplifiers of the auxiliary power amplifier 3 to work in class C is added at the connection part of the two second resistors B_C . In FIG. 7, R is used for both second resistors B The representation represents the resistance used for biasing.
Common-gate connected NMOS tube MN in two groups of common-source common-gate amplifiers of the main power amplifier 2 9 And MN (Mobile node) 10 Are connected together andis connected with corresponding bias voltage V B3 And bias voltage V B3 Through corresponding resistor R B Is connected to NMOS transistor MN 9 And MN (Mobile node) 10 Is formed on the substrate.
Common-gate connected NMOS tube MN in two groups of common-source common-gate amplifiers of the auxiliary power amplifier 3 11 And MN (Mobile node) 12 Is connected together and connected to a corresponding bias voltage V B4 And bias voltage V B4 Through corresponding resistor R B Is connected to NMOS transistor MN 11 And MN (Mobile node) 12 Is formed on the substrate.
Input transformer T 1 The center tap of the output end coil of (2) is connected with a bias voltage V B1 . In FIG. 7, R is used for each resistor B In actual use, the values of the resistors can be set as needed.
As shown in fig. 8, a comparison curve of the power backoff interval efficiency of the Doherty PA and the prior art circuit according to the preferred embodiment of the present invention;
the abscissa of curves 401, 402, and 403 is the output power back-off value, and the ordinate is the normalized efficiency.
Comparing curves 402 and 402, curve 402 and curve 403 overlap when the power back-off value is between 0dB and 12dB, and when the power back-off value is below 12dB, i.e., less than or equal to-12 dB, the preferred embodiment of the present invention switches the supply voltage to VDD/2, so that the efficiency of the main power amplifier 2 increases, as shown by curve 403 moving up when less than or equal to-12 dB, and the efficiency can reach 100% again in the power back-off interval below 12dB, at which time the main power amplifier 2 is re-saturated.
As shown in fig. 9, a probability density curve of LTE and IEEE802.11b is added to a comparison curve of the power backoff interval efficiency corresponding to fig. 8.
The present invention has been described in detail by way of specific examples, but these should not be construed as limiting the invention. Many variations and modifications may be made by one skilled in the art without departing from the principles of the invention, which is also considered to be within the scope of the invention.
Claims (13)
1. The Doherty power amplifier based on the transformer is characterized by comprising a main power amplifier and an auxiliary power amplifier which are connected in parallel, wherein the output end of the main power amplifier is connected with a primary coil of a main output transformer, the output end of the auxiliary power amplifier is connected with a primary coil of an auxiliary output transformer, and a secondary coil of the main output transformer is connected with a secondary coil of the auxiliary output transformer and forms an output end of a radio frequency output signal;
the center tap of the primary coil of the main output transformer is connected with the center tap of the primary coil of the auxiliary output transformer and forms a power supply voltage connecting end, and the power supply voltage connecting end is connected to a plurality of power supply voltages with different sizes through a plurality of selection switches; the power supply voltage corresponds to a power back-off interval of the Doherty power amplifier, the efficiency of the Doherty power amplifier in the corresponding power back-off interval is increased, and the larger the power back-off value of the power back-off interval of the Doherty power amplifier is, the smaller the power supply voltage is; conversely, the smaller the power back-off value of the power back-off interval of the Doherty power amplifier is, the larger the power supply voltage is;
the power supply voltage comprises 2 power supply voltages, namely a first voltage value and a second voltage value;
the first voltage value is 2 times the second voltage value.
2. The transformer-based Doherty power amplifier of claim 1, wherein: the power back-off interval corresponding to the first voltage value is back-off 0 dB-12 dB, and the power back-off interval corresponding to the second voltage value is back-off 12dB or more.
3. The transformer-based Doherty power amplifier of claim 1, wherein: the selection switch adopts a PMOS tube.
4. The transformer-based Doherty power amplifier of claim 1, wherein: the secondary coil of the main output transformer is connected with the secondary coil of the auxiliary output transformer in series, and the first end of the secondary coil of the main output transformer is the output end of the radio frequency output signal;
the second end of the secondary coil of the main output transformer is connected with the first end of the secondary coil of the auxiliary output transformer;
the second end of the secondary winding of the auxiliary output transformer is grounded.
5. The transformer-based Doherty power amplifier of claim 4, wherein: a capacitor is connected between the first end of the secondary winding of the main output transformer and the second end of the secondary winding of the auxiliary output transformer.
6. The transformer-based Doherty power amplifier of claim 1, wherein: and a bypass network circuit is connected between the power supply voltage connecting end and the ground.
7. The transformer-based Doherty power amplifier of claim 6, wherein: the bypass network circuit is a circuit formed by connecting a plurality of series circuits formed by connecting resistors and capacitors in parallel.
8. The transformer-based Doherty power amplifier of claim 1, wherein: the Doherty power amplifier further comprises a driving amplifier, wherein the input end of the driving amplifier is connected with a radio frequency input signal, and the output end of the driving amplifier is connected to the input end of the main power amplifier and the input end of the auxiliary power amplifier correspondingly.
9. The transformer-based Doherty power amplifier of claim 8, wherein: the main power amplifier operates in class AB and the auxiliary power amplifier operates in class C.
10. The transformer-based Doherty power amplifier of claim 8, wherein: the radio frequency input signal is connected to the input of the driver amplifier through an input transformer.
11. The transformer-based Doherty power amplifier of claim 8, wherein: the main power amplifier comprises a common-source common-gate amplifier formed by connecting two NMOS (N-channel metal oxide semiconductor) tubes;
the auxiliary power amplifier comprises a common-source common-gate amplifier formed by connecting two NMOS (N-channel metal oxide semiconductor) tubes.
12. The transformer-based Doherty power amplifier of claim 11, wherein: the radio frequency input signal is a differential signal;
the main power amplifier is of a differential structure formed by connecting two groups of symmetrical common-source and common-gate amplifiers;
the auxiliary power amplifier is of a differential structure formed by connecting two groups of symmetrical common-source and common-gate amplifiers.
13. The transformer-based Doherty power amplifier of claim 11, wherein: two first resistors with the same size are connected in series between two differential input ends of the main power amplifier, and bias voltages enabling two groups of common-source common-gate amplifiers of the main power amplifier to work in class AB are added at the connection part of the two first resistors;
two second resistors with the same size are connected in series between two differential input ends of the auxiliary power amplifier, and bias voltages enabling two groups of common-source common-gate amplifiers of the auxiliary power amplifier to work in class C are added at the connection position of the two second resistors.
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| CN109951159B (en) * | 2019-02-27 | 2023-05-02 | 上海华虹宏力半导体制造有限公司 | Doherty power amplifier based on transformer |
| CN111181508B (en) * | 2020-02-26 | 2023-08-22 | 上海华虹宏力半导体制造有限公司 | High-linearity radio frequency power amplifier |
| CN111211739A (en) * | 2020-02-26 | 2020-05-29 | 上海华虹宏力半导体制造有限公司 | Load modulation power amplifier |
| CN114050792A (en) * | 2022-01-10 | 2022-02-15 | 深圳飞骧科技股份有限公司 | Novel broadband Doherty radio frequency power amplifier |
| CN115940850B (en) * | 2023-02-23 | 2023-05-23 | 深圳飞骧科技股份有限公司 | Novel Doherty power amplifier of current synthesis formula |
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| CN106452370A (en) * | 2016-10-12 | 2017-02-22 | 杭州电子科技大学 | High-fallback Doherty power amplifier based on asymmetric structure and implementation method of high-fallback Doherty power amplifier |
| JP2018137566A (en) * | 2017-02-21 | 2018-08-30 | 株式会社村田製作所 | Power amplifier circuit |
| CN108768312B (en) * | 2018-07-23 | 2024-02-20 | 上海亮牛半导体科技有限公司 | Circuit structure and method for improving linearity of power amplifier by using adjustable inductance |
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| US10110177B1 (en) * | 2017-07-28 | 2018-10-23 | Silicon Laboratories Inc. | Programmable impedance control for a transformer |
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