Active biasing circuit and power amplification device

Abstract

The embodiment of the invention discloses an active bias circuit and a power amplification device, and belongs to the technical field of bias circuits. In the active bias circuit provided by the embodiment of the invention, an active bias module comprises a first depletion type tube, a second depletion type tube and a voltage division unit, the logic conversion module comprises a level control unit and a third depletion type tube. A logic conversion module is integrated into an active bias circuit, a level control unit of the logic conversion module drives a third depletion type tube to be turned on or turned off, and the level of a connection point between a source electrode of a first depletion type tube and a drain electrode of a second depletion type tube is switched, so that the bias function of the active bias module is controlled to be turned off or turned on. Switching of the on-off state of the power amplifier tube is achieved, a drain voltage modulation chip does not need to be additionally arranged on the drain electrode of the power amplifier tube, the cost of power amplification application is effectively saved, and the module area is reduced. Meanwhile, the threshold fluctuation of the power amplifier tube is desensitized, and the performance fluctuation of the power amplifier tube at high and low temperatures is reduced.

Description

Technical Field

[0001] Embodiments of the present application relate to the technical field of bias circuits, and in particular to an active bias circuit and a power amplifier device. Background Art

[0002] In the existing wireless transceiver system, the digital signal is modulated into a radio frequency signal of a specific frequency, and the modulated radio frequency signal is amplified by a power amplifier chip (power amplifier) ​​to enhance the transmission distance and strength of the radio frequency signal. In the power amplifier chip, gate voltage division and drain modulation are often used for the power amplifier tube to achieve the low power consumption (power down) function of the power amplifier chip; wherein, the gate voltage division method is to divide the power supply voltage through a resistor voltage division network and apply it to the gate of the power amplifier tube to accurately control the gate voltage; the drain modulation method is to control the working characteristics of the power amplifier tube by changing the voltage of the drain of the power amplifier tube, and realize the switching of the switch state of the power amplifier tube by adjusting the drain.

[0003] The power amplifier tube of the power amplifier chip often uses a depletion tube (D tube), and in the leakage modulation mode, an external leakage voltage modulation chip is often added to adjust the leakage switching state of the power amplifier tube. However, the leakage voltage modulation chip is relatively expensive and occupies a large module area, which easily leads to an increase in the cost of power amplifier applications and an increase in the module area. At the same time, the power amplifier chip is more sensitive to the threshold fluctuation of the power amplifier tube in the gate voltage division mode, and the performance of the power amplifier tube fluctuates greatly at high and low temperatures. Summary of the invention

[0004] The embodiments of the present application provide an active bias circuit and a power amplifier device, which can effectively save the cost of power amplifier applications and reduce the module area; at the same time, the threshold fluctuation of the power amplifier tube is desensitized and the performance fluctuation of the power amplifier tube under high and low temperature conditions is reduced.

[0005] The embodiment of the present application provides an active bias circuit, which is applied to a depletion-type power amplifier tube. The active bias circuit includes: an active bias module and a logic conversion module; the active bias module includes: a first depletion-type tube, a second depletion-type tube and a voltage divider unit; the logic conversion module includes: a level control unit and a third depletion-type tube;

[0006] The drain of the first depletion-type tube is connected to a positive voltage power supply, the source of the first depletion-type tube is connected to the gate of the first depletion-type tube and the drain of the second depletion-type tube, the gate of the first depletion-type tube and the gate of the second depletion-type tube are connected to a negative voltage power supply via the voltage divider unit, and one end of the voltage divider unit is connected to the gate of the power amplifier tube;

[0007] The level control unit is connected to the gate of the third depletion-type tube, the source of the third depletion-type tube is grounded, and the drain of the third depletion-type tube is connected to the drain of the second depletion-type tube; the level control unit is used to control the potential level of the gate of the third depletion-type tube and drive the third depletion-type tube to be turned on or off.

[0008] Further, the voltage dividing unit includes: a first resistor, a second resistor and a third resistor;

[0009] One end of the first resistor is connected to the source of the first depletion-type tube, the gate of the first depletion-type tube, and the drain of the second depletion-type tube;

[0010] The other end of the first resistor is connected to one end of the second resistor and the gate of the power amplifier tube;

[0011] The other end of the second resistor is connected to the gate of the second depletion-type transistor and one end of the third resistor, and the other end of the third resistor is connected to a negative voltage power supply.

[0012] Furthermore, the active bias module further includes: a fourth resistor;

[0013] One end of the fourth resistor is connected to the source of the first depletion-type transistor, and the other end of the fourth resistor is connected to the gate of the first depletion-type transistor and the drain of the second depletion-type transistor.

[0014] Furthermore, the active bias module further includes: a signal isolation unit; the signal isolation unit includes: a fifth resistor and a sixth resistor;

[0015] One end of the fifth resistor is connected to the voltage dividing unit, and the other end of the fifth resistor is connected to one end of the sixth resistor and the gate of the power amplifier tube;

[0016] The other end of the sixth resistor is connected to a negative voltage power supply.

[0017] Further, the level control unit includes: a fourth depletion-type transistor, a seventh resistor, an eighth resistor and a digital signal source;

[0018] The gate of the fourth depletion-type transistor is connected to the digital signal source via the seventh resistor;

[0019] The drain of the fourth depletion-type tube is connected to a positive voltage power supply and a gate of the third depletion-type tube;

[0020] The source of the fourth depletion-type transistor is connected to a positive voltage power supply and one end of the eighth resistor, and the other end of the eighth resistor is grounded.

[0021] Furthermore, the level control unit further includes: a potential shifting unit;

[0022] One end of the potential shifting unit is connected to the drain of the fourth depletion-type tube, and the other end of the potential shifting unit is connected to the gate of the third depletion-type tube; the potential shifting unit is used to convert the potential change of the drain of the fourth depletion-type tube into the potential change of the gate of the third depletion-type tube.

[0023] Further, the potential shifting unit includes: a ninth resistor, a tenth resistor, and an eleventh resistor;

[0024] One end of the ninth resistor is connected to the drain of the fourth depletion-type transistor, and the other end of the ninth resistor is connected to one end of the tenth resistor and one end of the eleventh resistor;

[0025] The other end of the tenth resistor is connected to the gate of the third depletion-type transistor, and the other end of the eleventh resistor is connected to a negative voltage power supply.

[0026] Furthermore, the level control unit further includes: a first resistance stabilizing unit and a second resistance stabilizing unit;

[0027] One end of the first resistance stabilizing unit is connected to a positive voltage power supply, and the other end of the first resistance stabilizing unit is connected to a drain of the fourth depletion-type tube;

[0028] One end of the second resistance stabilizing unit is connected to a positive voltage power supply, and the other end of the second resistance stabilizing unit is connected to a source of the fourth depletion-type transistor.

[0029] Further, the first resistance stabilizing unit includes: a fifth depletion-type transistor and a twelfth resistor, and the second resistance stabilizing unit includes: a sixth depletion-type transistor and a thirteenth resistor;

[0030] The drain of the fifth depletion-type tube is connected to a positive voltage power supply, the source of the fifth depletion-type tube is connected to one end of the twelfth resistor, and the gate of the fifth depletion-type tube is connected to the other end of the twelfth resistor and the drain of the fourth depletion-type tube;

[0031] The drain of the sixth depletion-type tube is connected to a positive voltage power supply, the source of the sixth depletion-type tube is connected to one end of the thirteenth resistor, and the gate of the sixth depletion-type tube is connected to the other end of the thirteenth resistor and the source of the fourth depletion-type tube.

[0032] The embodiment of the present application provides a power amplifier device, including: a depletion-type power amplifier tube and the above-mentioned active bias circuit, wherein the active bias circuit is connected to the gate of the power amplifier tube.

[0033] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0034] The active bias circuit of the embodiment of the present application is applied to a depletion-type power amplifier tube, and the active bias circuit includes: an active bias module and a logic conversion module; the active bias module includes: a first depletion-type tube, a second depletion-type tube and a voltage divider unit; the logic conversion module includes: a level control unit and a third depletion-type tube; the drain of the first depletion-type tube is connected to a positive voltage power supply, the source of the first depletion-type tube is connected to the gate of the first depletion-type tube and the drain of the second depletion-type tube, the gate of the first depletion-type tube and the gate of the second depletion-type tube are connected to a negative voltage power supply via the voltage divider unit, and one end of the voltage divider unit is connected to the gate of the power amplifier tube; the level control unit is connected to the gate of the third depletion-type tube, the source of the third depletion-type tube is grounded, and the drain of the third depletion-type tube is connected to the drain of the second depletion-type tube; the level control unit is used to control the potential level of the gate of the third depletion-type tube to drive the third depletion-type tube to be turned on or off.

[0035] It can be seen that in the embodiment of the present application, the logic conversion module is integrated into the active bias circuit, and the third depletion-type tube is driven to be turned on or off by the level control unit of the logic conversion module, and the connection point level between the source of the first depletion-type tube and the drain of the second depletion-type tube is switched to control the bias function of the active bias module to be turned off or on, so as to realize the switching of the switch state of the power amplifier tube, and there is no need to add a leakage voltage modulation chip to the drain of the power amplifier tube, which effectively saves the cost of power amplification application and reduces the module area. At the same time, the first depletion-type tube and the second depletion-type tube in the active bias module adopt the same type of depletion-type tube as the power amplifier tube, and the threshold changes of the depletion-type tube and the power amplifier tube in the active bias module are consistent, which can reduce the sensitivity to the threshold fluctuation of the power amplifier tube; and the first depletion-type tube and the second depletion-type tube can pull up the gate current of the power amplifier tube at high and low temperatures, thereby reducing the performance fluctuation of the power amplifier tube at high and low temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0037] Figure 1 A schematic diagram of an active bias circuit disclosed in an embodiment of the present application;

[0038] Figure 2 A schematic diagram of another active bias circuit disclosed in an embodiment of the present application;

[0039] Figure 3A waveform diagram corresponding to a positive voltage power supply disclosed in an embodiment of the present application;

[0040] Figure 4 A waveform diagram corresponding to a negative voltage power supply disclosed in an embodiment of the present application;

[0041] Figure 5 A waveform diagram corresponding to a threshold value of a power amplifier tube disclosed in an embodiment of the present application;

[0042] Figure 6 A waveform diagram corresponding to a temperature fluctuation disclosed in an embodiment of the present application;

[0043] Figure 7 A voltage waveform diagram corresponding to a digital signal source disclosed in an embodiment of the present application;

[0044] Figure 8 This is a current waveform diagram corresponding to a digital signal source disclosed in an embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0046] In the description of the embodiments of the present application, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the embodiments of the present application.

[0047] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0048] In existing power amplifier chips, leakage modulation is often used. The leakage modulation method controls the working characteristics of the power amplifier tube by changing the voltage of the drain of the power amplifier tube, and realizes the switching of the on-off state of the power amplifier tube by adjusting the leakage. The power amplifier tube of the power amplifier chip often adopts a depletion-type tube (D tube). In the leakage modulation method, an external leakage voltage modulation chip is often added to adjust the leakage of the power amplifier tube to switch the on-off state. However, the leakage voltage modulation chip is relatively expensive and occupies a large module area, which easily leads to an increase in the cost of power amplifier applications and an increase in the module area. Therefore, an embodiment of the present application provides an active bias circuit, which can effectively save the cost of power amplifier applications and reduce the module area; such as Figure 1 As shown, the details are as follows:

[0049] In an embodiment of the present application, an active bias circuit is applied to a depletion-type power amplifier PA, which is used to amplify an input signal at an input terminal IN and output it through an output terminal OUT; wherein the power amplifier can not only amplify radio frequency signals (that is, the power amplifier can be used as a radio frequency amplifier), but also amplify audio signals or video signals (that is, the power amplifier can be used as an audio amplifier); wherein the power amplifier includes: a depletion-type MOS tube or a depletion-type JFET tube (junction field effect transistor), which is not specifically limited here.

[0050] The active bias circuit includes: an active bias module 100 and a logic conversion module 200; wherein the active bias module 100 is connected to the gate of the power amplifier tube PA, and is used to provide a bias voltage to the gate of the power amplifier tube PA, and control the power amplifier tube PA to be turned on. The logic conversion module 200 is connected to the active bias module 100, and is used to control the bias function of the active bias module 100, that is, to control the active bias module 100 to output or stop outputting the bias voltage, and realize the turning on or off of the power switch tube PA.

[0051] Specifically, the active bias module 100 includes: a first depletion-type transistor PA1, a second depletion-type transistor PA2 and a voltage divider unit 101; the logic conversion module 200 includes: a level control unit 201 and a third depletion-type transistor PA3. The drain of the first depletion-type transistor PA1 is connected to a positive voltage power supply VD, one end of which is grounded; the positive voltage power supply VD is a drain constant voltage, used to provide a positive voltage, and the positive voltage power supply VD can be introduced by the drain voltage of the power amplifier tube PA. The source of the first depletion-type transistor PA1 is connected to the gate of the first depletion-type transistor PA1 and the drain of the second depletion-type transistor PA2; the gate of the first depletion-type transistor PA1 and the gate of the second depletion-type transistor PA2 are connected to a negative voltage power supply VN through the voltage divider unit 101, one end of which is grounded, and the drain of the second depletion-type transistor PA2 is grounded. The negative voltage power supply VN is a constant negative voltage potential, and the negative voltage value provided is less than the conduction threshold of the depletion-type tube, so as to turn on the first depletion-type tube PA1 and the second depletion-type tube PA2. One end of the voltage divider unit 101 is connected to the gate of the power amplifier tube PA, and the voltage divider unit 101 is used to provide a voltage to the second depletion-type tube PA2 through voltage division to control the drain-source current passing through the second depletion-type tube PA2, thereby synchronously controlling the drain-source current passing through the first depletion-type tube PA1, and providing a stable bias voltage to the gate of the power amplifier tube PA through the voltage divider unit 101.

[0052] In the logic conversion module 200, the level control unit 201 is connected to the gate of the third depletion-type tube PA3, the source of the third depletion-type tube PA3 is grounded, and the drain of the third depletion-type tube PA3 is connected to the drain of the second depletion-type tube PA2; the level control unit 201 is used to control the potential level of the gate of the third depletion-type tube PA3, and drive the third depletion-type tube PA3 to be turned on or off. It can be understood that for the depletion-type tube, when the gate-source voltage Vgs of the depletion-type tube is 0, the depletion-type tube is turned on, and when the gate voltage of the depletion-type tube is lower than the negative voltage threshold, the depletion-type tube is turned off; that is, the level control unit 201 can control the gate level of the third depletion-type tube PA3 to be 0V, that is, the gate-source voltage Vgs of the third depletion-type tube PA3 is 0, and drive the third depletion-type tube PA3 to be turned on, or can control the gate voltage of the third depletion-type tube PA3 to be lower than the negative voltage threshold, and drive the third depletion-type tube PA3 to be turned off. Among them, when the third depletion-type tube PA3 is turned on, the potential of point B of the active bias module 100 is pulled down to 0V, the gate potential of the power amplifier tube PA will be reduced to below the threshold potential, and the power amplifier tube PA is turned off; when the third depletion-type tube PA3 is turned off, the active bias module 100 works normally, and the output bias voltage drives the power amplifier tube PA to turn on. It can be seen that the logic conversion module 200 switches the level of point B between the connection point of the first depletion-type tube PA1 and the second depletion-type tube PA2, that is, switches the TTL level (TTL, transistor-transistor logic, Transistor-Transistor Logic), to achieve the switching state switching of the power switch tube PA.

[0053] It can be seen that the active bias circuit of the embodiment of the present application is applied to a depletion-type power amplifier tube, and the active bias circuit includes: an active bias module and a logic conversion module; the active bias module includes: a first depletion-type tube, a second depletion-type tube and a voltage divider unit; the logic conversion module includes: a level control unit and a third depletion-type tube; the drain of the first depletion-type tube is connected to a positive voltage power supply, the source of the first depletion-type tube is connected to a gate of the first depletion-type tube and a drain of the second depletion-type tube, the gate of the first depletion-type tube and the gate of the second depletion-type tube are connected to a negative voltage power supply via a voltage divider unit, and one end of the voltage divider unit is connected to the gate of the power amplifier tube; the level control unit is connected to the gate of the third depletion-type tube, the source of the third depletion-type tube is grounded, and the drain of the third depletion-type tube is connected to the drain of the second depletion-type tube; the level control unit is used to control the potential level of the gate of the third depletion-type tube to drive the third depletion-type tube to be turned on or off.

[0054] In the embodiment of the present application, the logic conversion module is integrated into the active bias circuit, and the third depletion-type tube is driven to be turned on or off by the level control unit of the logic conversion module, and the connection point level between the source of the first depletion-type tube and the drain of the second depletion-type tube is switched to control the bias function of the active bias module to be turned off or on, so as to realize the switching of the switching state of the power amplifier tube, and there is no need to add a leakage voltage modulation chip to the drain of the power amplifier tube, which effectively saves the cost of power amplification application and reduces the module area.

[0055] In one implementable manner, the traditional active bias structure is generally designed based on the enhancement tube (E tube), while the depletion tube (D tube) is often used in high-power power amplifier chips; if the traditional active bias structure is directly applied to the depletion tube, it is easy to be inapplicable and it is difficult to provide a bias voltage to the depletion tube normally. When the threshold of the power amplifier tube fluctuates, either the power amplifier tube is independently biased and debugged on a single chip, which is time-consuming; or the unified bias voltage is not debugged, resulting in poor consistency and low yield. In the embodiment of the present application, the first depletion tube and the second depletion tube in the active bias module use depletion tubes of the same type (i.e., the same process) as the power amplifier tube. The threshold changes of the depletion tube and the power amplifier tube in the active bias module are consistent, and the threshold fluctuations of the power amplifier tube can be perfectly tracked; compared with the gate voltage division method in the traditional power amplifier chip, which is more sensitive to threshold fluctuations, in the present application, the operating point deviation caused by the threshold fluctuation can be adaptively corrected, and the threshold fluctuation can be desensitized, thereby improving the yield of the power amplifier chip under the condition of a unified external bias voltage. Figure 5 As shown, Vth_ripple is the threshold of the power amplifier tube, and IDD is the gate current of the power amplifier tube.

[0056] In one practicable manner, when a conventional power amplifier chip adopts a gate voltage division method, when the power amplifier tube of the power amplifier chip is at a high temperature or a low temperature, if a uniform bias voltage is applied to the gate, the performance of the power amplifier tube will fluctuate greatly. In the present application, active devices are used in the active bias module: a first depletion-type tube and a second depletion-type tube, which can pull up the gate current of the power amplifier tube (i.e., raise the gate potential) at a high temperature or a low temperature, thereby improving the power capability of the power amplifier tube at low and high temperatures, reducing the performance fluctuation of the power amplifier tube at high and low temperatures, and improving the performance of the power amplifier tube at high or low temperatures. Figure 6 As shown, TA is the temperature and IDD is the gate current of the power amplifier tube.

[0057] Furthermore, the following will combine Figure 2 , the active bias circuit in this application is described as follows:

[0058] In the present application, the power amplifier tube PA can be integrated in the amplifier module 300, which includes: an input matching unit, an output matching unit and a power amplifier tube PA; the RF input terminal RFIN is connected to the gate of the power amplifier tube PA through the input matching unit, and the drain of the power amplifier tube PA is connected to the RF output terminal RFOUT through the output matching unit. Among them, the input matching unit includes: a first capacitor C1, a third capacitor C3 and a first inductor L1, and the output matching unit includes: a second capacitor C2, a fourth capacitor C4 and a second inductor L2. It can be understood that the connection method of the inductor and the capacitor in the input matching unit and the output matching unit can be other methods, or the specific composition architecture can be other architectures. The positive voltage power supply VD in the amplifier module 300 can be the same power supply as the positive voltage power supply VD in the active bias module 100, or a different power supply.

[0059] In the active bias module 100, the voltage divider unit 101 includes: a first resistor R1, a second resistor R2 and a third resistor R3; the first resistor R1, the second resistor R2 and the third resistor R3 are precision resistors, and the resistance values ​​can be set by themselves. Among them, one end of the first resistor R1 is connected to the source of the first depletion-type tube PA1, the gate of the first depletion-type tube PA1 and the drain of the second depletion-type tube PA2; the other end of the first resistor R1 is connected to one end of the second resistor R2 and the gate of the power amplifier tube PA; the other end of the second resistor R2 is connected to the gate of the second depletion-type tube PA2 and one end of the third resistor R3, and the other end of the third resistor R3 is connected to the negative voltage power supply VN. Among them, the resistance value of the first resistor R1 / the third resistor R3 is relatively large, and the current passing through the third resistor R3 is almost negligible; through the voltage division of the first resistor R1, the second resistor R2 and the third resistor R3, the drain-source current passing through the first depletion-type tube PA1 and the drain-source current passing through the second depletion-type tube PA2 are controlled to provide a corresponding bias voltage for the gate of the power amplifier tube PA.

[0060] Furthermore, in the gate voltage division mode of the traditional power amplifier chip, it is more sensitive to the fluctuation of the external gate voltage, and the external gate voltage needs to be stabilized by a linear regulator (LDO chip), which is not conducive to the integration of the power amplifier chip. In the present application, the active bias module 100 also includes: a fourth resistor R4; wherein one end of the fourth resistor R4 is connected to the source of the first depletion-type tube PA1, and the other end of the fourth resistor R4 is connected to the gate of the first depletion-type tube PA1 and the drain of the second depletion-type tube PA2. By adjusting the fourth resistor R4, the voltage of the positive power supply VD can be reasonably distributed to the first depletion-type tube PA1 and the second depletion-type tube PA2, so that the first depletion-type tube PA1 and the second depletion-type tube PA2 work in the constant current region. At this time, even when the external gate voltage (i.e., the bias voltage in the active bias module 100: the positive voltage power supply VD and the negative voltage power supply VN) fluctuates, it does not affect the performance of the second depletion transistor PA2, that is, it is insensitive to the VD / VN fluctuation, and there is no need to stabilize the external gate voltage through a linear regulator (LDO chip), which is conducive to the integration of power amplifier chips. Figure 3 as well as Figure 4 As shown in the figure, IDD is the gate current of the power amplifier tube.

[0061] Furthermore, the active bias module 100 also includes: a signal isolation unit 102, which is used to isolate the leakage signal that may exist in the gate of the power amplifier tube from entering the active bias module, such as isolating the RF leakage signal of the RF amplifier tube from entering the active bias module. Among them, the signal isolation unit 102 includes: a fifth resistor R5 and a sixth resistor R6; one end of the fifth resistor R5 is connected to the voltage divider unit 101, and the other end of the fifth resistor R5 is connected to one end of the sixth resistor R6 and the gate of the power amplifier tube PA; the other end of the sixth resistor R6 is connected to the negative voltage power supply VN. It can be understood that if there is a gate current in the power amplifier tube PA, the gate current can be diverted to the negative voltage power supply VN by adjusting the sixth resistor R6 without entering the fifth resistor R5. Otherwise, the gate current is too large to enter the fifth resistor R5, which will affect the performance of the active bias module at high and low temperatures.

[0062] Furthermore, in the existing power amplifier chip, the switch state of the power amplifier tube is switched by leakage modulation, and because the drain voltage and drain current of the power amplifier tube are large, the switching time of the leakage modulation method is relatively slow; and for high-power amplifier chips, the bilateral delay is not synchronized when the drain is adjusted, forming positive feedback to continuously strengthen the input signal, thereby causing self-oscillation and even the risk of chip burning. In the embodiment of the present application, the level control unit of the logic conversion module drives the third depletion tube to turn on or off, and switches the connection point level between the source of the first depletion tube and the drain of the second depletion tube to control the bias function of the active bias module to turn off or on; that is, the power amplifier tube is controlled by adjusting the gate to switch the power amplifier tube; because the gate voltage of the power amplifier tube is much lower than the drain voltage, and the gate current is much lower than the drain current, the switch state of the power amplifier tube can be quickly switched, and the risk of self-excitation of the power amplifier tube during the switching process is also reduced.

[0063] Specifically, the level control unit includes: a fourth depletion-type tube PA4, a seventh resistor R7, an eighth resistor R8 and a digital signal source PD; the gate of the fourth depletion-type tube PA4 is connected to the digital signal source PD via the seventh resistor R7; the drain of the fourth depletion-type tube PA4 is connected to the positive voltage power supply VD and the gate of the third depletion-type tube PA3; wherein the positive voltage power supply VD in the logic conversion module 200 and the positive voltage power supply VD in the active bias module can be introduced by the drain voltage of the power amplifier tube PA. The source of the fourth depletion-type tube PA4 is connected to the positive voltage power supply VD and one end of the eighth resistor R8, and the other end of the eighth resistor R8 is grounded. It can be understood that the potentials at both ends of the eighth resistor R8 determine the PD signal flip potential point (i.e., the flip potential point at which the PD signal controls the fourth depletion-type tube PA4 to be turned on or off).

[0064] The process of switching the switch state of the power amplifier tube by the logic conversion module 200 is as follows: when the signal of the digital signal source PD is switched from a high level to a low level, the fourth depletion-type tube PA4 is turned off (cut off), the potential of point A (i.e., the gate of the fourth depletion-type tube PA4) rises from a low level to a high level, the gate potential of the third depletion-type tube PA3 rises from a negative voltage to 0V, the third depletion-type tube PA3 is turned on, the potential of point B in the active bias module 100 (TTL level) is pulled down to 0V, and the potential of point C (the gate of the power amplifier tube PA) is reduced to below the threshold potential, so that the power amplifier tube PA is turned off. When the signal of the digital signal source PD is switched from a low level to a high level, the fourth depletion-type tube PA4 is turned on, the potential of point A (i.e., the gate of the fourth depletion-type tube PA4) drops from a high level to a low level, the gate potential of the third depletion-type tube PA3 drops from a negative voltage, the third depletion-type tube PA3 is turned off, and the active bias module 100 normally outputs a bias voltage to point C (the gate of the power amplifier tube PA) to turn on the power amplifier tube PA. It can be seen that in the embodiment of the present application, the logic conversion module 200 adjusts the gate of the power amplifier tube PA through the signal of the digital signal source PD through the active bias module 100, and can quickly switch the switch state of the power amplifier tube. Figure 7 as well as Figure 8 As shown, VGS is the gate voltage of the power amplifier tube PA, and IDD is the gate current of the power amplifier tube PA.

[0065] Further, the level control unit also includes: a potential shifting unit 2011; one end of the potential shifting unit 2011 is connected to the drain of the fourth depletion-type tube PA4, and the other end of the potential shifting unit 2011 is connected to the gate of the third depletion-type tube PA3; the potential shifting unit 2011 is used to convert the potential change of the drain of the fourth depletion-type tube PA4 into the potential change of the gate of the third depletion-type tube PA3. For example, the potential of the drain of the fourth depletion-type tube PA4 (i.e., point A) rises from a low level: 2V to a high level: 5V, and the gate potential of the third depletion-type tube PA3 rises from a negative voltage: -3V to 0V. The conduction or shutdown of the third depletion-type tube PA3 is accurately controlled by the potential shifting unit. It can be understood that the potential shifting unit 2011 can be composed of one or more of a resistor, an operational amplifier or a diode, which is not specifically limited here.

[0066] For example, the potential shifting unit 2011 includes: a ninth resistor R9, a tenth resistor R10, and an eleventh resistor R11; one end of the ninth resistor R9 is connected to the drain of the fourth depletion transistor PA4, and the other end of the ninth resistor R9 is connected to one end of the tenth resistor R10 and one end of the eleventh resistor R11; the other end of the tenth resistor R10 is connected to the gate of the third depletion transistor PA3, and the other end of the eleventh resistor R11 is connected to the negative voltage power supply VN. It can be understood that the positive voltage power supply VD in the active bias module 100 and the logic conversion module 200 can be the same power supply or different power supplies; the negative voltage power supply VN in the active bias module 100 and the logic conversion module 200 can be the same power supply or different power supplies.

[0067] Furthermore, in order to stabilize the current passing through the fourth depletion-type tube PA4, so that the fourth depletion-type tube PA4 can stably control the conduction or shutdown of the third depletion-type tube PA3; in the embodiment of the present application, the level control unit also includes: a first resistance stabilizing unit 2012 and a second resistance stabilizing unit 2013; one end of the first resistance stabilizing unit 2012 is connected to the positive voltage power supply VD, and the other end of the first resistance stabilizing unit 2012 is connected to the drain of the fourth depletion-type tube PA4; one end of the second resistance stabilizing unit 2013 is connected to the positive voltage power supply VD, and the other end of the second resistance stabilizing unit 2013 is connected to the source of the fourth depletion-type tube PA4. The first resistance stabilizing unit 2012 and the second resistance stabilizing unit 2013 can make the fourth depletion-type tube PA4 work in the constant current region, and when the positive voltage power supply VD and the negative voltage power supply VN fluctuate, the level control effect of the fourth depletion-type tube PA4 is not affected.

[0068] For example, the first resistance stabilizing unit 2012 includes: a fifth depletion-type transistor PA5 and a twelfth resistor R12, and the second resistance stabilizing unit 2013 includes: a sixth depletion-type transistor PA6 and a thirteenth resistor R13; the drain of the fifth depletion-type transistor PA5 is connected to the positive voltage power supply VD, the source of the fifth depletion-type transistor PA5 is connected to one end of the twelfth resistor R12, the gate of the fifth depletion-type transistor PA5 is connected to the other end of the twelfth resistor R12 and the drain of the fourth depletion-type transistor PA4; the drain of the sixth depletion-type transistor PA6 is connected to the positive voltage power supply VD, the source of the sixth depletion-type transistor PA6 is connected to one end of the thirteenth resistor R13, the gate of the sixth depletion-type transistor PA6 is connected to the other end of the thirteenth resistor R13 and the source of the fourth depletion-type transistor PA4. It can be understood that the resistance values ​​of the eighth resistor R8, the twelfth resistor R12 and the thirteenth resistor R13 can be adjusted to make the fourth depletion-type transistor PA4, the fifth depletion-type transistor PA5 and the sixth depletion-type transistor PA6 work in the constant current region.

[0069] Preferably, all depletion-type tubes in the active bias module and the logic conversion module are depletion-type tubes of the same type (i.e., the same process) as the power amplifier tube, so that the active bias circuit composed of the active bias module and the logic conversion module can effectively track the threshold changes of the power amplifier tube and ensure the normal operation of the power amplification function.

[0070] An embodiment of the present application also provides a power amplifier device, which can be called a power amplifier chip or a power amplifier. The power amplifier device includes: a depletion-type power amplifier tube and the above-mentioned active bias circuit, wherein the active bias circuit is connected to the gate of the power amplifier tube.

[0071] The above described device or equipment embodiments are merely illustrative, wherein the unit modules described as separate components may or may not be physically separated, and the components displayed as module units may or may not be physical units, i.e., they may be located in one place, or may be distributed on multiple network module units. Some or all of the modules may be selected according to actual needs to achieve the objectives of the present embodiment.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Under the concept of the present application, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes in different aspects of the present application as above, which are not provided in detail for the sake of simplicity. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An active bias circuit, applied to a depletion-type power amplifier tube, characterized in that: The active bias circuit includes: an active bias module and a logic conversion module; the active bias module includes: a first depletion-type transistor, a second depletion-type transistor and a voltage divider unit; the logic conversion module includes: a level control unit and a third depletion-type transistor; The drain of the first depletion-type tube is connected to a positive voltage power supply, the source of the first depletion-type tube is connected to the gate of the first depletion-type tube and the drain of the second depletion-type tube, the gate of the first depletion-type tube and the gate of the second depletion-type tube are connected to a negative voltage power supply via the voltage divider unit, and one end of the voltage divider unit is connected to the gate of the power amplifier tube; The level control unit is connected to the gate of the third depletion-type tube, the source of the third depletion-type tube is grounded, and the drain of the third depletion-type tube is connected to the drain of the second depletion-type tube; the level control unit is used to control the potential level of the gate of the third depletion-type tube and drive the third depletion-type tube to be turned on or off.

2. The active bias circuit according to claim 1, characterized in that: The voltage dividing unit includes: a first resistor, a second resistor and a third resistor; One end of the first resistor is connected to the source of the first depletion-type tube, the gate of the first depletion-type tube, and the drain of the second depletion-type tube; The other end of the first resistor is connected to one end of the second resistor and the gate of the power amplifier tube; The other end of the second resistor is connected to the gate of the second depletion-type transistor and one end of the third resistor, and the other end of the third resistor is connected to a negative voltage power supply.

3. The active bias circuit according to claim 2, characterized in that: The active bias module further includes: a fourth resistor; One end of the fourth resistor is connected to the source of the first depletion-type transistor, and the other end of the fourth resistor is connected to the gate of the first depletion-type transistor and the drain of the second depletion-type transistor.

4. The active bias circuit according to claim 1, characterized in that: The active bias module further includes: a signal isolation unit; the signal isolation unit includes: a fifth resistor and a sixth resistor; One end of the fifth resistor is connected to the voltage dividing unit, and the other end of the fifth resistor is connected to one end of the sixth resistor and the gate of the power amplifier tube; The other end of the sixth resistor is connected to a negative voltage power supply.

5. The active bias circuit according to claim 1, characterized in that: The level control unit includes: a fourth depletion-type transistor, a seventh resistor, an eighth resistor and a digital signal source; The gate of the fourth depletion-type transistor is connected to the digital signal source via the seventh resistor; The drain of the fourth depletion-type tube is connected to a positive voltage power supply and a gate of the third depletion-type tube; The source of the fourth depletion-type transistor is connected to a positive voltage power supply and one end of the eighth resistor, and the other end of the eighth resistor is grounded.

6. The active bias circuit according to claim 5, characterized in that: The level control unit further includes: a potential shifting unit; One end of the potential shifting unit is connected to the drain of the fourth depletion-type tube, and the other end of the potential shifting unit is connected to the gate of the third depletion-type tube; the potential shifting unit is used to convert the potential change of the drain of the fourth depletion-type tube into the potential change of the gate of the third depletion-type tube.

7. The active bias circuit according to claim 6, characterized in that: The potential shifting unit includes: a ninth resistor, a tenth resistor, and an eleventh resistor; One end of the ninth resistor is connected to the drain of the fourth depletion-type transistor, and the other end of the ninth resistor is connected to one end of the tenth resistor and one end of the eleventh resistor; The other end of the tenth resistor is connected to the gate of the third depletion-type transistor, and the other end of the eleventh resistor is connected to a negative voltage power supply.

8. The active bias circuit according to claim 5, characterized in that: The level control unit further includes: a first resistance stabilizing unit and a second resistance stabilizing unit; One end of the first resistance stabilizing unit is connected to a positive voltage power supply, and the other end of the first resistance stabilizing unit is connected to a drain of the fourth depletion-type tube; One end of the second resistance stabilizing unit is connected to a positive voltage power supply, and the other end of the second resistance stabilizing unit is connected to a source of the fourth depletion-type transistor.

9. The active bias circuit according to claim 8, characterized in that: The first resistance stabilizing unit includes: a fifth depletion-type transistor and a twelfth resistor, and the second resistance stabilizing unit includes: a sixth depletion-type transistor and a thirteenth resistor; The drain of the fifth depletion-type tube is connected to a positive voltage power supply, the source of the fifth depletion-type tube is connected to one end of the twelfth resistor, and the gate of the fifth depletion-type tube is connected to the other end of the twelfth resistor and the drain of the fourth depletion-type tube; The drain of the sixth depletion-type tube is connected to a positive voltage power supply, the source of the sixth depletion-type tube is connected to one end of the thirteenth resistor, and the gate of the sixth depletion-type tube is connected to the other end of the thirteenth resistor and the source of the fourth depletion-type tube.

10. A power amplifier device, characterized in that: include: A depletion-type power amplifier tube and an active bias circuit as described in any one of claims 1 to 9, wherein the active bias circuit is connected to the gate of the power amplifier tube.

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