A bias circuit for a power amplifier, a power amplifier module, and a power amplifier chip

Abstract

The present invention discloses a bias circuit for a power amplifier, a power amplifier module, and a power amplifier chip, relating to the technical field of power amplifiers. Through the connection relationship of at least two transistors of the composite transistor structure, compared with the triode series structure in the traditional bias circuit, the feedback intensity to temperature changes is increased, achieving better temperature compensation. Due to the self-heating effect in the transistor when the temperature rises in the composite transistor structure, the connection relationship between the first circuit, the first transistor, and the power amplifier causes the currents in at least two transistors of the composite transistor structure to be superimposed, resulting in an increase in the voltage drop corresponding to the first circuit and suppressing the increase in the bias current of the power amplifier. Conversely, when the temperature decreases, the static current value of the bias current of the power amplifier tends to be stable, and thus the slope of the current change with the increase in temperature is relatively small, keeping the signal distortion-free and improving the temperature compensation ability of the power amplifier.

Description

Technical Field

[0001] The present invention relates to the technical field of power amplifiers, and particularly to a bias circuit, a power amplifier module, and a power amplifier chip for a power amplifier. Background Art

[0002] Power amplifiers play a crucial role in wireless transceiver systems, mainly used to enhance the power and range of signals. Among them, bipolar semiconductor triodes are widely used in the design of power amplifiers.

[0003] Currently, bipolar semiconductor triodes have self-heating effects and self-bias effects, resulting in changes in the transconductance of transistors, an increase in their current amplification factor, and poor linearity, thereby leading to unstable signal distortion. To solve the current problems, Figure 1 As shown in the schematic diagram of the active bias circuit for the current bipolar semiconductor triode, as Figure 1 shown, the bipolar semiconductor triode here uses a heterojunction bipolar transistor (HBT) device. The triode series structure composed of two PN junctions D1 and D2, together with HBT1, constitutes a mirror current source to provide a base bias voltage with temperature compensation characteristics for HBT0. However, the current triode series structure has a weak temperature compensation ability, resulting in a large slope change in the collector current of HBT0 with the increase in temperature. When the power amplifier operates, the bias current of HBT0 changes significantly with temperature, thereby affecting the linearity and efficiency of the power amplifier.

[0004] Therefore, how to improve the temperature compensation ability of power amplifiers is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] The objective of the present invention is to provide a bias circuit, a power amplifier module, and a power amplifier chip for a power amplifier to solve the problem of large changes in the bias current caused by insufficient temperature compensation ability of the current bipolar semiconductor triode, thereby affecting the linearity and efficiency of the power amplifier.

[0006] To solve the above technical problems, the present invention provides a bias circuit for a power amplifier, including a first circuit, a first transistor, and a composite transistor composed of at least two transistors; wherein, the emitter of the current transistor of the composite transistor is connected to the base of the next transistor, and the base of the first transistor is connected to the base of the first transistor; the collectors of the remaining transistors of the composite transistor except the first transistor are interconnected; the emitter of the last transistor is grounded;

[0007] The first end of the first circuit is connected to the collector of the first transistor and is also connected to the collector of the first transistor of the composite transistor;

[0008] The second end of the first circuit is connected to the collectors of the transistors in the composite transistor except the first transistor, and is also connected to the base of the first transistor and the base of the first transistor in the composite transistor;

[0009] The emitter of the first transistor is connected to the power amplifier.

[0010] On the one hand, the number of transistors in the composite transistor is two, including the first transistor and the last transistor;

[0011] The collector of the first transistor is connected to the first end of the first circuit and is also connected to the collector of the first transistor;

[0012] The base of the first transistor is connected to the base of the first transistor, and is also connected to the second end of the first circuit and the collector of the last transistor; the emitter of the first transistor is connected to the base of the last transistor;

[0013] The emitter of the last transistor is grounded.

[0014] On the other hand, the number of transistors in the composite transistor is N, and N is an integer greater than 2;

[0015] The collector of the first transistor is connected to the first end of the first circuit and is also connected to the collector of the first transistor; the base of the first transistor is connected to the base of the first transistor and is also connected to the second end of the first circuit; the emitter of the first transistor is connected to the base of the i-th transistor;

[0016] The emitter of the i-th transistor is connected to the base of the (i + 1)-th transistor; the collectors of the i-th transistor and the (i + 1)-th transistor are connected to each other and are also connected to the second end of the first circuit, the base of the first transistor, and the base of the first transistor; where 1 < i < N;

[0017] The collector of the N-th transistor is connected to the collector of the i-th transistor and is also connected to the second end of the first circuit, the base of the first transistor, and the base of the first transistor; the emitter of the N-th transistor is grounded.

[0018] On the other hand, each transistor in the composite transistor is a bipolar transistor.

[0019] On the other hand, a power supply is further included;

[0020] The first end of the first circuit is connected to the power supply.

[0021] On the other hand, the first circuit includes at least a first resistor;

[0022] The first end of the first resistor is connected to the power supply, and is connected to the collector of the first transistor and the collector of the first transistor in the composite transistor.

[0023] The second end of the first resistor is connected to the collectors of the transistors in the composite transistor other than the first transistor, and is connected to the base of the first transistor and the base of the first transistor in the composite transistor.

[0024] On the other hand, it further includes a second resistor;

[0025] The first end of the second resistor is connected to the emitter of the first transistor;

[0026] The second end of the second resistor is connected to the RF input end of the power amplifier.

[0027] On the other hand, it further includes a first capacitor;

[0028] The first end of the first capacitor is connected to the base of the first transistor, and is connected to the base of the first transistor in the composite transistor, the second end of the first circuit and the collectors of the transistors in the composite transistor other than the first transistor; the second end of the first capacitor is grounded.

[0029] On the other hand, it further includes a third resistor;

[0030] The first end of the third resistor is connected to the first end of the first circuit;

[0031] The second end of the third resistor is connected to the collector of the first transistor, and is connected to the collector of the first transistor in the composite transistor.

[0032] On the other hand, it further includes a fourth resistor and a fifth resistor;

[0033] The first end of the fourth resistor is connected to the emitter of the previous transistor of two adjacent transistors in the composite transistor; the second end of the fourth resistor is connected to the base of the next transistor of two adjacent transistors in the composite transistor;

[0034] The first end of the fifth resistor is connected to the emitter of the last transistor in the composite transistor; the second end of the fifth resistor is grounded.

[0035] To solve the above technical problems, the present invention provides a power amplifier module, including a power amplifier and the bias circuit of the above-mentioned power amplifier.

[0036] On the one hand, the type of the transistor in the bias circuit is the same as that of the corresponding transistor of the power amplifier.

[0037] To solve the above technical problems, the present invention further provides a power amplifier chip, including the bias circuit of the power amplifier described above.

[0038] A bias circuit of a power amplifier provided by the present invention includes a first circuit, a first transistor, and a composite transistor composed of at least two transistors; the emitter of the current transistor of the composite transistor is connected to the base of the next transistor, and the base of the first transistor is connected to the base of the first transistor; the collectors of the remaining transistors of the composite transistor except the first transistor are connected to each other; the emitter of the last transistor is grounded; the first end of the first circuit is connected to the collector of the first transistor and the collector of the first transistor of the composite transistor; the second end of the first circuit is connected to the collectors of the remaining transistors of the composite transistor except the first transistor, and is connected to the base of the first transistor and the base of the first transistor of the composite transistor; the emitter of the first transistor is connected to the power amplifier. By the connection relationship of at least two transistors of the composite transistor structure, compared with the triode series structure in the traditional bias circuit, the feedback intensity to temperature change is increased, so as to achieve better temperature compensation. Since the self-heating effect in the transistor occurs when the temperature of the composite transistor structure rises, the currents in at least two transistors of the composite transistor structure are superimposed, resulting in an increase in the voltage drop corresponding to the first circuit, thereby suppressing the increase in the bias current of the power amplifier. On the contrary, when the temperature decreases, the decrease in the bias current of the power amplifier is also effectively suppressed, so that the static current value of the bias current of the power amplifier tends to be stable, and then the slope of the current change with the increase of temperature is small, keeping the signal distortion-free and improving the temperature compensation ability of the power amplifier.

[0039] In addition, the present invention further provides a power amplifier module and a power amplifier chip, which have the same beneficial effects as the bias circuit of the power amplifier described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] To more clearly illustrate the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0041] Figure 1 Schematic diagram of the active bias circuit of the current bipolar semiconductor triode;

[0042] Figure 2 Structural diagram of a bias circuit of a power amplifier provided by an embodiment of the present invention;

[0043] Figure 3 Structural diagram of a composite transistor composed of N transistors provided by an embodiment of the present invention;

[0044] Figure 4 It is a structural diagram of another bias circuit of a power amplifier provided by an embodiment of the present invention;

[0045] Figure 5 It is a schematic diagram for comparing the bias circuit provided by an embodiment of the present invention with a traditional bias circuit. Specific embodiments

[0046] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0047] The core of the present invention is to provide a bias circuit, a power amplifier module and a power amplifier chip of a power amplifier to solve the problem of large variation in bias current caused by insufficient temperature compensation ability of a current bipolar semiconductor triode, thereby affecting the linearity and efficiency of the power amplifier.

[0048] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0049] It should be noted that power amplifiers are widely used in wireless communication devices such as mobile phones, base stations, Wireless Fidelity (WiFi), and the Internet of Things. However, bipolar semiconductor triodes have inherent self-heating effects and self-bias effects. When used in high-linear power amplifiers, a suitable active bias circuit needs to be adopted to provide temperature compensation and adaptive linearization bias for the amplification transistor. As Figure 1 shown, two PN junctions D1 and D2 form a transistor series structure, which together with HBT1 constitutes a mirror current source to provide a base bias voltage with temperature compensation characteristics for HBT0. The current mirror current source provides relatively weak temperature compensation ability. Therefore, the bias circuit of the power amplifier provided by the present invention can solve the above technical problems.

[0050] Figure 2 It is a structural diagram of a bias circuit of a power amplifier provided by an embodiment of the present invention. As Figure 2 shown, it includes a first circuit 1, a first transistor Q1, and a composite transistor 2 composed of at least two transistors; wherein, the emitter of the current transistor of the composite transistor 2 is connected to the base of the next transistor, and the base of the first transistor is connected to the base of the first transistor Q1; the collectors of the remaining transistors of the composite transistor 2 except the first transistor are connected to each other; the emitter of the last transistor is grounded;

[0051] The first end of the first circuit 1 is connected to the collector of the first transistor Q1 and the collector of the first transistor of the composite transistor 2;

[0052] The second end of the first circuit 1 is connected to the collectors of the transistors of the composite transistor 2 other than the first transistor, and is connected to the base of the first transistor Q1 and the base of the first transistor of the composite transistor 2;

[0053] The emitter of the first transistor Q1 is connected to the power amplifier 3.

[0054] Specifically, for the amplifier composed of transistors to amplify the signal without distortion, it is necessary to ensure that the emitter junction of the transistor is forward-biased and the collector junction is reverse-biased. That is, its operating point should be set. The so-called operating point is to make the base, emitter, and collector of the transistor at the required potentials through the setting of the external circuit. Here, the external circuit is the bias circuit.

[0055] The composite transistor 2 is composed of at least two transistors. The current amplified by the first transistor can be further amplified by the remaining transistors, and a much higher current gain than any one of the transistors can be provided to achieve efficient current amplification. Its structure is to connect the emitter of the current transistor to the base of the next transistor, connect the base of the first transistor to the base of the first transistor Q1, connect the collectors of the transistors of the composite transistor 2 other than the first transistor to each other, and connect the emitter of the last transistor to the ground. The temperature compensation current is to select the appropriate resistor in the active bias circuit so that the active bias circuit provides appropriate temperature compensation. The first transistor Q1 and the composite transistor 2 are used to combine the bias current corresponding to the temperature compensation of the connected first circuit 1 so that the power amplifier 3 can maintain the stability of its static current value according to the bias current.

[0056] When the temperature rises, due to the decrease in the bias voltage of the first transistor Q1, the bias current given to the power amplifier 3 decreases, thereby suppressing the increase in the bias current of the power amplifier 3 and keeping the static current value within a relatively stable range. When the temperature drops, the bias voltage of the first transistor Q1 rises for temperature compensation, thereby suppressing the decrease in the bias current of the power amplifier 3 and maintaining the stability of the static current value. The essence of temperature compensation is to compensate the current so that the static current value remains within a stable range.

[0057] Specifically, when the temperature rises, due to the self-heating effect of the transistor, the threshold voltage of the transistor drifts negatively, and the static current value of the transistor increases. Due to the composite transistor structure, compared with the traditional series structure of triodes, the currents of the transistors in the composite transistor 2 of the present invention are superimposed, causing the voltage in the first circuit 1 on the same circuit to increase sharply. Since the first circuit 1 is connected to the collector of the first transistor Q1 and its power supply voltage remains unchanged, the base voltage of the first transistor Q1 drops sharply to suppress the increase in the bias current in the power amplifier 3. When the temperature drops, the same is true, and it can effectively suppress the decrease in the bias current of the power amplifier 3.

[0058] A bias circuit for a power amplifier provided by an embodiment of the present invention includes a first circuit, a first transistor, and a composite transistor composed of at least two transistors; the emitter of the current transistor of the composite transistor is connected to the base of the next transistor, and the base of the first transistor is connected to the base of the first transistor; the collectors of the remaining transistors of the composite transistor except the first transistor are connected to each other; the emitter of the last transistor is grounded; the first end of the first circuit is connected to the collector of the first transistor and is also connected to the collector of the first transistor of the composite transistor; the second end of the first circuit is connected to the collectors of the remaining transistors of the composite transistor except the first transistor, and is also connected to the base of the first transistor and the base of the first transistor of the composite transistor; the emitter of the first transistor is connected to the power amplifier. By the connection relationship of at least two transistors in the composite transistor structure, compared with the series structure of triodes in the traditional bias circuit, the feedback intensity to temperature changes is increased, achieving better temperature compensation. Due to the self-heating effect in the transistor when the temperature rises in the composite transistor structure, the currents in at least two transistors of the composite transistor structure are superimposed, resulting in an increase in the voltage drop corresponding to the first circuit, thereby suppressing the increase in the bias current of the power amplifier. Conversely, when the temperature drops, it also effectively suppresses the decrease in the bias current of the power amplifier, making the static current value of the bias current of the power amplifier tend to be stable, and further making the slope of the current change with the increase in temperature smaller, maintaining the signal without distortion, and improving the temperature compensation ability of the power amplifier.

[0059] Further, usually, the number of transistors in the composite transistor 2 is two, as Figure 2 shown, including the first transistor and the last transistor;

[0060] The collector of the first transistor is connected to the first end of the first circuit and is also connected to the collector of the first transistor;

[0061] The base of the first transistor is connected to the base of the first transistor, and is also connected to the second end of the first circuit and the collector of the last transistor; the emitter of the first transistor is connected to the base of the last transistor;

[0062] The emitter of the last transistor is grounded.

[0063] Specifically, the first transistor and the last transistor are exemplified by the second transistor Q2 and the third transistor Q3 respectively. The collector of the second transistor Q2 is connected to the first end of the first circuit 1 and the collector of the first transistor Q1;

[0064] The base of the second transistor Q2 is connected to the base of the first transistor Q1, and is connected to the second end of the first circuit 1 and the collector of the third transistor Q3; the emitter of the second transistor Q2 is connected to the base of the third transistor Q3;

[0065] The emitter of the third transistor Q3 is grounded.

[0066] It can be understood that the first transistor Q1 can be a unipolar device or a bipolar device. For the first transistor and the last transistor (the second transistor Q2 and the third transistor Q3 for example), they are both bipolar devices. Since the amplification effect of the current needs to be utilized for compensation, after the emitter current of the second transistor Q2 increases, through the amplification effect of the third transistor Q3, the collector current of the third transistor Q3 increases more. At this time, the voltage drop of the first circuit 1 increases, which in turn causes the base voltages of the second transistor Q2 and the third transistor Q3 to drop, so that the current corresponding to the emitter of the first transistor Q1 drops, and the static current of the power amplifier 3 increases due to the temperature rise. Compared with the traditional series structure of triodes in the bias circuit, the feedback intensity to temperature changes is increased, achieving better temperature compensation and making it more effective to maintain the stability of the static bias current of the power amplifier.

[0067] When the temperature rises, the threshold voltage of the BE junction of the power amplifier 3 drifts negatively, and the collector static current Icq0 of the power amplifier 3 increases by ΔIcq0; at this time, the threshold voltages of the second transistor Q2 and the third transistor Q3 also drift negatively, and Icq2 and Icq3 also increase by ΔIcq2 and ΔIcq3 respectively with the increase of temperature. Among them, the current change amount ΔIcq2 of the second transistor Q2 flows into the base of the third transistor Q3 and is superimposed with the collector current of the third transistor Q3 itself after being amplified by the third transistor Q3, so that the collector current of the third transistor Q3 increases sharply to ΔIcq3 + β * ΔIcq2 with the increase of temperature, where β is the transistor amplification factor. The voltage drop on the first circuit 1 also increases sharply, so that the base voltage of the first transistor Q1 drops sharply, thereby suppressing the increase of the bias current ΔIcq0 of the power amplifier 3. It should be noted that the resistance value of the first circuit 1 needs to be calculated in advance to ensure that the compensation current of the first transistor Q1 caused by the change of the voltage drop due to the change of the current can compensate for the rising current of the power amplifier 3. Conversely, when the temperature drops, the active bias circuit of the present invention can also more effectively suppress the drop of the bias current of the power amplifier 3.

[0068] In this embodiment, through the specific transistor structure of the composite transistor, the feedback intensity to temperature changes is increased, achieving better temperature compensation and improving the temperature compensation ability.

[0069] In some embodiments, the number of transistors in the composite transistor is N, and N is an integer greater than 2;

[0070] The collector of the first transistor is connected to the first end of the first circuit and to the collector of the first transistor; the base of the first transistor is connected to the base of the first transistor and to the second end of the first circuit; the emitter of the first transistor is connected to the base of the i-th transistor;

[0071] The emitter of the i-th transistor is connected to the base of the (i + 1)-th transistor; the collector of the i-th transistor and the collector of the (i + 1)-th transistor are connected to each other and to the second end of the first circuit, the base of the first transistor, and the base of the first transistor; where 1 < i < N;

[0072] The collector of the N-th transistor is connected to the collector of the i-th transistor and is connected to the second end of the first circuit, the base of the first transistor, and the base of the first transistor; the emitter of the N-th transistor is grounded.

[0073] Figure 3 The figure shows a structure diagram of a composite transistor composed of N transistors provided by an embodiment of the present invention. As Figure 3 shown, the transistors in the composite transistor are represented by Q1'-QN', where N' is greater than 2. The collector of the first transistor Q1' is connected to the first end of the first circuit 1 and to the collector of the first transistor Q1. The base of the first transistor Q1' is connected to the base of the first transistor Q1' and to the second end of the first circuit. The emitter of the first transistor is connected to the base of the i-th transistor Qi';

[0074] The emitter of the i-th transistor Qi' is connected to the base of the (i + 1)-th transistor Qi+1'; the collector of the i-th transistor Qi' and the collector of the (i + 1)-th transistor Qi+1' are connected to each other and to the second end of the first circuit, the base of the first transistor Q1', and the base of the first transistor Q1; where 1 < i < N;

[0075] The collector of the N-th transistor QN' is connected to the collector of the i-th transistor Qi' and is connected to the second end of the first circuit, the base of the first transistor Q1', and the base of the first transistor Q1; the emitter of the N-th transistor QN' is grounded.

[0076] The composite transistor formed by connecting N transistors provided by the embodiment of the present invention has a corresponding gain amplification multiple, which increases the feedback intensity to temperature changes and achieves better temperature compensation.

[0077] In some embodiments, each transistor in the composite transistor is a bipolar transistor.

[0078] Specifically, the types of the transistors in the composite transistor are the same, and they are all bipolar transistors, such as Heterojunction Bipolar Transistors (HBTs), which have the ability to operate at high speeds and are suitable for high-frequency applications such as radio frequency power amplification and laser driving. It improves the injection efficiency and current gain by using different semiconductor materials to manufacture the emitter and base.

[0079] In some embodiments, the circuit further includes a power supply Vbias;

[0080] The first end of the first circuit 1 is connected to the power supply Vbias.

[0081] In the field of power management, the power supply Vbias usually refers to the bias voltage, which is used to ensure that electronic devices or circuits can operate normally. In some Linear Regulator (LDO) chips, Vbias may be used to provide voltage for the internal control circuit or drive circuit to achieve better performance. For example, in some LDO chips, the Vbias pin may require a voltage higher than the output voltage (Vout) to ensure normal operation under low dropout conditions, which helps to achieve ultra-low dropout. Based on the above embodiments, in some embodiments, the first circuit 1 includes at least a first resistor R1;

[0082] The first end of the first resistor R1 is connected to the power supply, and is connected to the collector of the first transistor Q1 and the collector of the first transistor in the composite transistor 2.

[0083] The second end of the first resistor R1 is connected to the collectors of the remaining transistors in the composite transistor 2 except the first transistor, and is connected to the base of the first transistor Q1 and the base of the first transistor in the composite transistor 2.

[0084] The first circuit 1 includes at least a first resistor R1, and the specific connection relationship is as Figure 2 shown, combined with the composite transistor 2 and the first transistor Q1, to provide a base bias current with temperature compensation characteristics to the power amplifier 3.

[0085] Based on some embodiments, further, Figure 4 This is a structural diagram of another bias circuit of the power amplifier provided by the embodiment of the present invention, as Figure 4 shown, the circuit further includes a second resistor R2;

[0086] The first end of the second resistor R2 is connected to the emitter of the first transistor Q1;

[0087] The second terminal of the second resistor R2 is connected to the radio frequency input terminal of the power amplifier 3.

[0088] It can be understood that the second resistor R2 provides ballast for the power amplifier 3 to keep the current stable. The ballast circuit controls its own shunt action through the transmitted temperature voltage signal to effectively control the main current control source of the base of the power amplifier 3, thereby preventing the concentration of the emitter current and keeping the bias current of the power amplifier stable.

[0089] In some embodiments, as Figure 4 shown, it further includes a first capacitor C1;

[0090] The first terminal of the first capacitor C1 is connected to the base of the first transistor Q1, and is connected to the base of the first transistor of the composite transistor 2, the second terminal of the first circuit 1, and the collectors of the transistors of the composite transistor 2 other than the first transistor.

[0091] The second terminal of the first capacitor C1 is grounded.

[0092] It can be understood that the first capacitor C1 is used for the bias of the adaptive linear effect. As the input power of RFin increases, the BE junction voltage of the power amplifier 3, actually the fourth transistor Q4, decreases, and its corresponding base current Ib0 increases, causing the transconductance g of the power amplifier m to change. The BE structure of the first capacitor C1 and the first transistor Q1 forms a low-impedance radio frequency channel. The radio frequency input signal flows through the BE junction of the first transistor Q1 to be rectified to obtain an appropriate ΔVBE1 of the first transistor Q1 to compensate the base bias voltage of the power amplifier 3, thereby improving the linearity of the amplifying transistor. For example, when the first transistor in the composite transistor is the second transistor Q2 and there is one other transistor, which is the third transistor Q3, the first terminal of the first capacitor C1 is connected to the base of the first transistor Q1 and the base of the second transistor Q2, and is connected to the collector of the third transistor Q3 and the second terminal of the first circuit 1.

[0093] Based on the above embodiments, in some embodiments, as Figure 4 shown, it further includes a second capacitor C2;

[0094] The first terminal of the second capacitor C2 is connected to the radio frequency input terminal of the power amplifier 3, and the second terminal of the second capacitor C2 is connected to the second terminal of the second resistor R2.

[0095] The function of the second capacitor in this embodiment is to block direct current and pass alternating current so that the radio frequency signal input to the power amplifier is an alternating current signal.

[0096] In some embodiments, as Figure 4 shown, it further includes a third resistor R3;

[0097] The first end of the third resistor R3 is connected to the first end of the first circuit 2;

[0098] The second end of the third resistor R3 is connected to the collector of the first transistor Q1 and to the collector of the first transistor in the composite transistor.

[0099] It can be understood that, as Figure 4 shown, taking the first transistor in the composite transistor as the second transistor Q2 as an example, the second end of the third resistor R3 is connected to the collector of the first transistor Q1 and to the collector of the second transistor Q2.

[0100] The third resistor in this embodiment is used to adjust the voltage of the bias circuit, making the adjustment of the bias circuit more flexible. Further, a fourth resistor R4 and a fifth resistor R5 are also included;

[0101] The first end of the fourth resistor R4 is connected to the emitter of the previous transistor of two adjacent transistors in the composite transistor 2; the second end of the fourth resistor R4 is connected to the base of the next transistor of two adjacent transistors in the composite transistor 2;

[0102] The first end of the fifth resistor R5 is connected to the emitter of the last transistor in the composite transistor 2; the second end of the fifth resistor R5 is grounded.

[0103] Specifically, taking Figure 4 as an example, the first transistor and the last transistor in the composite transistor correspond to the second transistor Q2 and the third transistor Q3 respectively. The first end of the fourth resistor R4 is connected to the emitter of the second transistor Q2, and the second end of the fourth resistor R4 is connected to the base of the third transistor Q3;

[0104] The first end of the fifth resistor R5 is connected to the emitter of the third transistor Q3, and the second end of the fifth resistor R5 is grounded.

[0105] If there are N transistors in the composite transistor, then correspondingly, the first end of the fourth resistor R4 is connected to the emitter of the previous transistor of two adjacent transistors in the composite transistor 2; the second end of the fourth resistor R4 is connected to the base of the next transistor of two adjacent transistors in the composite transistor 2;

[0106] The first end of the fifth resistor R5 is connected to the emitter of the last transistor in the composite transistor 2; the second end of the fifth resistor R5 is grounded. It should be noted that since the number of transistors is N, the number of corresponding fourth resistors is multiple, and this embodiment is only a general expression.

[0107] The fourth resistor and the fifth resistor in this embodiment provide relatively perfect temperature compensation on the basis of the first circuit composed of the first resistor, improving the temperature compensation ability.

[0108] The power amplifier 3 is an important component of various wireless transmitters. In the front-end circuit of the transmitter, the radio frequency signal power generated by the modulation oscillation circuit is small and needs to go through a series of amplification - buffer stage, intermediate amplification stage, and final power amplification stage to obtain sufficient radio frequency power before it can be fed to the antenna for radiation. The power amplifier 3 can be implemented through a power amplification chip, and its core is still composed of triodes, field effect transistors, or Metal-Oxide-Semiconductor (MOS) transistors. This is not limited here and can be set according to the actual situation.

[0109] Furthermore, the present invention also provides a power amplifier module, which includes a power amplifier and the bias circuit of the above power amplifier. For the introduction of a bias circuit provided by the present invention, please refer to the above circuit embodiments. The present invention will not elaborate here, and it has the same beneficial effects as the bias circuit of the above power amplifier.

[0110] In some embodiments, the types of transistors in the bias circuit and the corresponding transistors of the power amplifier are the same.

[0111] Specifically, the types of transistors in the bias circuit are the same as those of the corresponding transistors of the power amplifier, which can be bipolar transistors, and the collector current is controlled by the base current. In addition, it has good versatility and can reduce production and maintenance costs.

[0112] Furthermore, the present invention also provides a power amplifier chip. For the introduction of a power amplifier chip provided by the present invention, please refer to the above circuit embodiments. The present invention will not elaborate here, and it has the same beneficial effects as the bias circuit of the above power amplifier.

[0113] Specifically, the bias circuit and the power amplifier can be set on one chip or separately. This is not limited here and can be set according to the actual situation.

[0114] Figure 5 It is a schematic diagram comparing the bias circuit provided by the embodiment of the present invention with the traditional bias circuit. As Figure 5 shown, the abscissa is temperature, and the ordinate is the collector current value of the radio frequency power amplifier. The thick line in the figure is the slope change of the traditional bias circuit ( Figure 1 bias circuit), and the thin line is the slope change corresponding to the bias circuit of the present invention. It can be seen that the slope change trend corresponding to the bias circuit provided by the present invention is relatively slow, while the slope change of the traditional bias circuit is larger. This shows that the temperature compensation ability of the bias circuit of the present invention is Figure 1 better than that of the bias circuit.

[0115] The bias circuit, power amplifier module, and power amplifier chip provided by the present invention have been introduced in detail above. The various embodiments in the specification are described in a progressive manner, and the key point of each embodiment is the difference from other embodiments. The same or similar parts among the various embodiments can be referred to each other. It should be noted that for those of ordinary skill in the art in the technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

[0116] It should also be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including the element.

Claims

1. A bias circuit for a power amplifier, characterized in that, It includes a first circuit, a first transistor, and a composite transistor composed of at least two transistors; wherein, the emitter of the current transistor of the composite transistor is connected to the base of the next transistor, and the base of the first transistor is connected to the base of the first transistor; the collectors of the remaining transistors of the composite transistor except the first transistor are interconnected; the emitter of the last transistor is grounded; The first end of the first circuit is connected to the collector of the first transistor and the collector of the first transistor of the composite transistor; The second end of the first circuit is connected to the collectors of the remaining transistors of the composite transistor except the first transistor, and is connected to the base of the first transistor and the base of the first transistor of the composite transistor; The emitter of the first transistor is connected to a power amplifier; Correspondingly, the number of transistors in the composite transistor is N, and N is an integer greater than 2; The collector of the first transistor is connected to the first end of the first circuit and the collector of the first transistor; the base of the first transistor is connected to the base of the first transistor and the second end of the first circuit; the emitter of the first transistor is connected to the base of the i-th transistor; The emitter of the i-th transistor is connected to the base of the (i + 1)-th transistor; the collectors of the i-th transistor and the (i + 1)-th transistor are interconnected and connected to the second end of the first circuit, the base of the first transistor, and the base of the first transistor; where 1 < i < N; The collector of the N-th transistor is connected to the collector of the i-th transistor and is connected to the second end of the first circuit, the base of the first transistor, and the base of the first transistor; the emitter of the N-th transistor is grounded; where the collector current of the N-th transistor is determined by its own current change amount and the current amplification factor and the collector current change amount of the previous transistor, so that when the temperature rises, due to the transistor self-heating effect, the currents of the N transistors are superimposed, and then the voltage drop of the first circuit increases, suppressing the increase of the bias current; when the temperature drops, the decrease of the bias current is suppressed, and the corresponding static current value tends to be stable; Correspondingly, it further includes: A fourth resistor and a fifth resistor; The first end of the fourth resistor is connected to the emitter of the previous transistor of two adjacent transistors in the composite transistor; the second end of the fourth resistor is connected to the base of the next transistor of two adjacent transistors in the composite transistor; The first end of the fifth resistor is connected to the emitter of the last transistor in the composite transistor; the second end of the fifth resistor is grounded.

2. The bias circuit of the power amplifier according to claim 1, wherein Each transistor in the composite transistor is a bipolar transistor.

3. The bias circuit of the power amplifier according to claim 1, wherein It further includes a power supply; The first end of the first circuit is connected to the power supply.

4. The bias circuit of the power amplifier according to claim 1, characterized in that, The first circuit includes at least a first resistor; The first end of the first resistor is connected to the power supply and is connected to the collector of the first transistor and the collector of the first transistor in the composite transistor; The second end of the first resistor is connected to the collectors of the remaining transistors of the composite transistor except the first transistor, and is connected to the base of the first transistor and the base of the first transistor of the composite transistor.

5. The bias circuit of the power amplifier according to claim 2, characterized in that, It further includes a second resistor; The first end of the second resistor is connected to the emitter of the first transistor; The second end of the second resistor is connected to the RF input end of the power amplifier.

6. The bias circuit of the power amplifier according to claim 1, wherein It further includes a first capacitor; The first end of the first capacitor is connected to the base of the first transistor, and is connected to the base of the first transistor of the composite transistor, the second end of the first circuit, and the collectors of the transistors of the composite transistor other than the first transistor; the second end of the first capacitor is grounded.

7. The bias circuit of the power amplifier according to claim 2, characterized in that, It further includes a third resistor; The first end of the third resistor is connected to the first end of the first circuit; The second end of the third resistor is connected to the collector of the first transistor, and is connected to the collector of the first transistor in the composite transistor.

8. A power amplifier module, characterized in that, It includes a power amplifier and a bias circuit of the power amplifier according to any one of claims 1 to 7 above.

9. The power amplifier module according to claim 8, wherein The type of the transistor in the bias circuit is the same as that of the corresponding transistor of the power amplifier.

10. A power amplifier chip, characterized in that, It includes a bias circuit of the power amplifier according to any one of claims 1 to 7 above.

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