Adaptive high back-off efficiency millimeter wave power amplifier system based on active load modulation

Abstract

The present invention discloses an adaptive high back-off efficiency millimeter wave power amplifier system based on active load modulation, including a power divider, a power coupler and an amplitude phase regulator, and a power amplifier C, {power amplifier A, ..., power amplifier A+X} and {power amplifier I, ..., power amplifier I+Y} arranged between the power divider and the power coupler, whose working states are respectively adjusted by independent voltage regulators; an amplitude phase regulator is arranged between the power divider and the power amplifier C. According to the change of the flow state from high to low, the working state of {power amplifier A, ..., power amplifier A+X} is adjusted from the AB class working state to the C class working state in turn. The present invention adopts active load modulation and dynamically adjusts the state of each power amplifier, improves the back-off efficiency of the power amplifier under low flow state, greatly reduces the dissipation of power consumption of the base station in the idle state, and has good practicality.

Description

Technical Field

[0001] The present invention belongs to the technical field of millimeter wave power amplifiers, and in particular relates to an adaptive high back-off efficiency millimeter wave power amplifier system based on active load modulation. Background Art

[0002] With the development of communication technology, green and low-carbon requirements are becoming more and more important, and the requirements for the fallback efficiency of amplifiers are becoming higher and higher. In the working state, the existing base station works at 50% traffic for 80% of the time, and the power amplifier consumes more than 70% of the power consumption of the radio remote unit of the entire base station. In this state, the efficiency of the power amplifier module is very low. Therefore, improving the working efficiency at 50% traffic is urgent and has received increasing attention from operators in recent years.

[0003] At present, the most commonly used method to improve the backoff efficiency is the Doherty technology, but it is usually used under 100% traffic conditions, because the use of Doherty technology to achieve greater backoff efficiency will cause a sharp deterioration of EVM. For example: Figure 1 As shown in the figure, in the traditional 3way Doherty structure, the power amplifier A, power amplifier I and power amplifier II are all operated at different threshold voltages through independent voltage controllers. Among them, power amplifier A works in class A mode, power amplifier I and power amplifier II work in class C mode, when the input signal amplitude is less than the preset value 1, power amplifier I and power amplifier II are in a non-conducting state; when the input signal is equal to the preset value 1, the efficiency of power amplifier A reaches the maximum; when the input power is greater than threshold 1 and less than threshold 2, power amplifier I is turned on, and when the input power is equal to threshold 2, power amplifier I reaches the maximum efficiency; when the input power is greater than threshold 2 and less than threshold 3, power amplifier II is turned on, and when the input power is equal to threshold 3, power amplifier II reaches the maximum efficiency. Summary of the invention

[0004] The purpose of the present invention is to provide an adaptive high back-off efficiency millimeter wave power amplifier system based on active load modulation, which adopts active load modulation and dynamically adjusts the state of each power amplifier so that the power amplifier can maintain the highest efficiency even when working at 50% flow state.

[0005] The present invention is mainly achieved through the following technical solutions:

[0006] An adaptive high back-off efficiency millimeter wave power amplifier system based on active load modulation comprises a power divider, a power coupler and an amplitude phase regulator, and a power amplifier C, {power amplifier A, ..., power amplifier A+X} and {power amplifier I, ..., power amplifier I+Y} arranged between the power divider and the power coupler, the working states of which are respectively adjusted by independent voltage regulators; an amplitude phase regulator is arranged between the power divider and the power amplifier C, and the amplitude phase regulator is used to couple the output power of the power amplifier C into the power amplifier A;

[0007] When working under 100% flow state, the working states of {power amplifier A, ..., power amplifier A+X} and power amplifier C are class AB working states, and the working state of {power amplifier I, ..., power amplifier I+Y} is class C working state; according to the change of flow state from high to low, the working state of {power amplifier A, ..., power amplifier A+X} is adjusted from class AB working state to class C working state in turn.

[0008] In order to better implement the present invention, further, in the process of adjusting from the 100% flow state to the 50% flow state, the amplitude phase regulator is used to increase the impedance of the node A between the output end of the power amplifier A and the power coupler to {Z0, X / (X-1)×Z0, X / (X-2)×Z0, ..., X×Z0} in sequence; the current of the {power amplifier A, ..., power amplifier A+X} is reduced to {I max , (X-1) / X*I max ,…,I max / X } , in each flow state, make the current of {power amplifier A, ..., power amplifier A + X} × the impedance of node A equal to Z0 × I max , remain unchanged;

[0009] Where: Z0 is the impedance of node A when it works at 100% flow state;

[0010] I max is the maximum on-state current of the power amplifier;

[0011] X is the number of power amplifiers.

[0012] In order to better realize the present invention, further, power amplifier A, power amplifier B, power amplifier C, power amplifier I and power amplifier II are arranged between the power distributor and the power coupler, and their working states are adjusted by independent voltage regulators respectively; when working under 100% flow state, the working states of power amplifier A, power amplifier B and power amplifier C are class AB working states, and the working states of power amplifier I and power amplifier II are class C working states; when adjusted from 100% flow state to 50% flow state, the working state of power amplifier B is adjusted to class C working state.

[0013] In order to better implement the present invention, further, when working under 50% flow state, the power voltage of node A between the output end of the power amplifier A and the power coupler is:

[0014] A×e j×θ1 ,

[0015] Where: A is the voltage amplitude value of the power at node A;

[0016] j is the imaginary unit;

[0017] θ1 is the voltage phase value of the power at node A;

[0018] The voltage amplitude value A and the voltage phase value θ1 are changed by adjusting the amplitude phase regulator.

[0019] In order to better implement the present invention, further, a phase regulator A and a phase regulator B are respectively arranged between the output ends of the power amplifier B and the power amplifier I, and between the output ends of the power amplifier I and the power amplifier II.

[0020] In order to better implement the present invention, further, the power coupler is grounded through a load.

[0021] The beneficial effects of the present invention are as follows:

[0022] The present invention adopts active load modulation and dynamically adjusts the state of each power amplifier, so that the power amplifier can maintain the highest efficiency even when working under 50% traffic state. The present invention dynamically adjusts the working state of the power amplifier to achieve a very high efficiency state under very large back-off conditions (50% traffic). The present invention can improve the back-off efficiency of the power amplifier under low traffic conditions, greatly reduce the power dissipation of the base station in the idle state, and provide a perfect solution for realizing a green and low-carbon base station solution. Secondly, the present invention can appropriately increase (stack) the number of power amplifiers A and power amplifiers I, adaptively adjust the efficiency that needs to be improved under different traffic conditions, and has good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the circuit schematic diagram of the traditional 3-way Doherty;

[0024] Figure 2 The circuit schematic diagram of the high-efficiency millimeter-wave power amplifier based on active load modulation of the present invention;

[0025] Figure 3 : is the efficiency change curve of the millimeter wave power amplifier in Example 1 and the traditional 3-way Doherty;

[0026] Figure 4 is a circuit schematic diagram of the millimeter wave power amplifier in Example 2;

[0027] Figure 5 is a typical IV curve of a power amplifier;

[0028] Figure 6 1 is the efficiency change curve of the millimeter wave power amplifier in Example 2 and the traditional 3-way Doherty. DETAILED DESCRIPTION

[0029] Embodiment 1:

[0030] An adaptive high back-off efficiency millimeter wave power amplifier system based on active load modulation, such as Figure 2 As shown, it includes a power divider, a power coupler and an amplitude phase regulator, and a power amplifier C, {power amplifier A, ..., power amplifier A+X} and {power amplifier I, ..., power amplifier I+Y} arranged between the power divider and the power coupler, whose working states are respectively adjusted by independent voltage regulators; an amplitude phase regulator is arranged between the power divider and the power amplifier C; when working under 100% flow state, the working state of the {power amplifier A, ..., power amplifier A+X} and the power amplifier C is the AB class working state, and the working state of the {power amplifier I, ..., power amplifier I+Y} is the C class working state.

[0031] The present invention can appropriately increase the number of power amplifiers A and power amplifiers I to change the efficiency under different flow conditions that need to be improved, such as increasing from two to multiple, to achieve an improvement in efficiency under low flow conditions.

[0032] According to the flow state from high to low, the working state of the {power amplifier A, ..., power amplifier A+X} is adjusted from the AB working state to the C state in turn. At the same time, the amplitude phase regulator is dynamically adjusted so that the impedance of node A is increased to {Z0, X / (X-1)×Z0, X / (X-2)×Z0, ..., X×Z0} in turn; at this time, the current of {power amplifier A, ..., power amplifier A+X} is reduced to {Imax , (X-1) / X*I max ,…,I max / X}. Therefore, in each state, current*impedance is equal to Z0*I max , remains unchanged (the maximum value of each amplifier under ideal conditions).

[0033] The calculation formula of the efficiency η of the millimeter wave power amplifier is:

[0034]

[0035] Where: R L is the load impedance of the power amplifier;

[0036] I max is the maximum on-state current of the power amplifier;

[0037] V DD Supply voltage to the system.

[0038] like Figure 3 As shown in the figure, not only does the efficiency reach a maximum of 78.5% at 50% flow rate, but it also maintains an efficiency of 78.5% at lower flow rates. Under each flow rate, the efficiency η of the power amplifier is equal to Π / 4, which is approximately equal to 78.5%, maintaining the maximum efficiency under each efficiency state.

[0039] Embodiment 2:

[0040] An adaptive high back-off efficiency millimeter wave power amplifier system based on active load modulation, such as Figure 4 As shown, it includes a power divider, a power coupler and an amplitude phase regulator, and power amplifiers A, B, C, I and II arranged between the power divider and the power coupler. The power amplifiers A, B, I, II and C are regulated in working state by independent voltage regulators respectively.

[0041] When the working state is 100% flow state, power amplifier A, power amplifier B, and power amplifier C work in class AB working state. Power amplifier I and power amplifier II work in class C working state, and they together form a group of Doherty working state. At this time, under 100% flow state, the efficiency reaches the maximum state.

[0042] When the working state is at 50% flow state, the power amplifier B is adjusted from the AB class working state to the C class working state, reducing the DC power consumption. At the same time, the amplitude phase regulator is adjusted so that the output power of the power amplifier C can be properly coupled into the power amplifier A. After calculation, when the signal injected by the power amplifier to node A meets the correct conditions (reference algorithm model), the output impedance of node A is improved, and the efficiency is maximized again under the 50% flow state.

[0043] Compared with the traditional solution, the power amplifier A, amplitude phase regulator, power amplifier C and power coupler designed in the present invention achieve the maximum efficiency (node ​​A) under the 50% flow state.

[0044] For the amplifier, when working in Class AB state, the power amplifier is in the on state, that is, a DC current will flow through the amplifier at this time. Under the most ideal conditions, 21.5% of the power will still be converted into heat and dissipated into the air, limiting the efficiency improvement of the entire solution under the 50% flow state. However, when the power amplifier B is adjusted from Class AB state to Class C state, 0% heat consumption can be achieved under the most ideal conditions.

[0045] However, for power amplifier A, since the impedance of node A has not changed at this time, referring to the η formula, due to the change of power amplifier B from class AB to class C, the current I max If the power amplifier C and the amplitude phase regulator are adjusted, the efficiency will decrease accordingly. At this time, we consider adjusting the power amplifier C and the amplitude phase regulator, adjusting (increasing) the impedance of node A, so that it is consistent with the efficiency of the power amplifier B working in the AB state (100% flow state), and the efficiency is maximum. The reference RF power P RF The output formula shows that the output power is reduced, that is, the flow state is reduced to 50%.

[0046] RF power P RF The output formula is:

[0047]

[0048] Where: R L is the load impedance of the power amplifier;

[0049] I max is the maximum on-state current of the power amplifier.

[0050] The algorithm model of the present invention is:

[0051] For node A, the power voltage injected into node A by power amplifier C is A×e j×θ1 At this time, the combined output power voltage of power amplifier A, power amplifier B, power amplifier I and power amplifier II is B×ej×θ2 , the characteristic impedance of node A is Z0.

[0052] Then the impedance of node A to power amplifier A, power amplifier B, power amplifier I and power amplifier II is:

[0053]

[0054] Among them: e is a natural constant;

[0055] Z0 is the characteristic impedance of node A;

[0056] A is the voltage amplitude value of the power injected into the C amplifier at node A;

[0057] B is the voltage amplitude value of the common injected power of {power amplifier A, ..., power amplifier A+X} at node A;

[0058] j is the imaginary unit;

[0059] θ1 is the voltage phase value of the power injected into the C amplifier at node A;

[0060] θ2 is the voltage phase value of the common injected power of {power amplifier A, ..., power amplifier A+X} at node A.

[0061] The present invention changes the values ​​of A and θ1 by adjusting the amplitude phase regulator.

[0062] It can be seen that adjusting A, B, θ1, θ2 can adjust the impedance value of node A, thereby adjusting the efficiency of power amplifier A, power amplifier B, power amplifier I and power amplifier II under the 50% flow state output, and achieving high efficiency under the 50% flow state. For example: when θ1=θ2=0, A=3*B, at this time Z=2*Z0, the impedance of point A is doubled.

[0063] like Figure 5 and Figure 6 As shown in the figure, when the flow rate is 50%, the threshold voltage of power amplifier B is reduced and it is not working. Power amplifier B and power amplifier A are transistors of the same size. At this time, Imax is reduced to half of the original value (compared to the 100% flow rate state). From the analysis at node A, it can be known that R L (Z) impedance increases to 2 times (compared to 100% flow state) because V DD is the system supply voltage, which remains unchanged. From the efficiency η formula, we know that the efficiency is the same as the 100% flow state, and V DD =R L *Imax, the power amplifier efficiency reaches a maximum of 78.5%.

[0064] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. An adaptive high back-off efficiency millimeter wave power amplifier system based on active load modulation, characterized in that: The invention comprises a power divider, a power coupler and an amplitude phase regulator, and a power amplifier C, {power amplifier A, ..., power amplifier A+X} and {power amplifier I, ..., power amplifier I+Y} arranged between the power divider and the power coupler, the working states of which are respectively regulated by independent voltage regulators; an amplitude phase regulator is arranged between the power divider and the power amplifier C, and the amplitude phase regulator is used to couple the output power of the power amplifier C into the power amplifier A; When working under 100% flow state, the working states of {power amplifier A, ..., power amplifier A+X} and power amplifier C are class AB working states, and the working state of {power amplifier I, ..., power amplifier I+Y} is class C working state; according to the change of flow state from high to low, the working state of {power amplifier A, ..., power amplifier A+X} is adjusted from class AB working state to class C working state in turn.

2. The millimeter wave power amplifier system with adaptive high back-off efficiency based on active load modulation according to claim 1, characterized in that: In the process of adjusting from the 100% flow state to the 50% flow state, the amplitude phase regulator is used to increase the impedance of the node A between the output end of the power amplifier A and the power coupler to {Z0, X / (X-1)×Z0, X / (X-2)×Z0, ..., X×Z0} in sequence; the current of the {power amplifier A, ..., power amplifier A+X} is reduced to {I max , (X-1) / X*I max ,…,I max / X}, in each flow state, the current of {power amplifier A, ..., power amplifier A+X} × the impedance of node A is equal to Z0 × I max , remain unchanged; Where: Z0 is the impedance of node A when it works at 100% flow state; I max is the maximum on-state current of the power amplifier; X is the number of power amplifiers.

3. The millimeter wave power amplifier system with adaptive high back-off efficiency based on active load modulation according to claim 1, characterized in that: Power amplifier A, power amplifier B, power amplifier C, power amplifier I and power amplifier II are arranged between the power distributor and the power coupler, and their working states are adjusted by independent voltage regulators respectively; when working under 100% flow state, the working states of power amplifier A, power amplifier B and power amplifier C are class AB working states, and the working states of power amplifier I and power amplifier II are class C working states; when adjusting from 100% flow state to 50% flow state, the working state of power amplifier B is adjusted to class C working state.

4. The millimeter wave power amplifier system with adaptive high back-off efficiency based on active load modulation according to claim 3, characterized in that: When working under 50% flow state, the power voltage of node A between the output end of the power amplifier A and the power coupler is: A×e j×θ1 , Where: A is the voltage amplitude value of the power at node A; j is the imaginary unit; θ1 is the voltage phase value of the power at node A; The voltage amplitude value A and the voltage phase value θ1 are changed by adjusting the amplitude phase regulator.

5. The millimeter wave power amplifier system with adaptive high back-off efficiency based on active load modulation according to claim 3, characterized in that: A phase regulator A and a phase regulator B are respectively arranged between the output ends of the power amplifier B and the power amplifier I, and between the output ends of the power amplifier I and the power amplifier II.

6. The millimeter wave power amplifier system with adaptive high back-off efficiency based on active load modulation according to claim 1, characterized in that: The power coupler is connected to ground via the load.

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