Bias circuit board

Abstract

The bias circuit board is a printed circuit board (PCB) with double-sided wiring, and a bias circuit and a high-frequency transmission line used for being connected with a power amplifier are arranged on the bias circuit board. The bias circuit comprises a self-resonance circuit arranged on the side of the first circuit panel, and a decoupling filter circuit, an amplification circuit, an isolation circuit, a power sharing circuit and a work holding circuit which are arranged on the second circuit panel. The self-resonance circuit is used for restraining backflow of an electric signal output by the power amplifier, the decoupling filter circuit is used for reducing the Q value of the self-resonance circuit, the power sharing circuit is used for voltage division, the work holding circuit is used for providing a direct-current power source for the amplifying circuit, and the amplifying circuit is used for providing stable static working current for the power amplifier. The isolation circuit is used for suppressing fluctuation of output current signals of the amplification circuit caused by internal resistance changes of the power amplifier. As the self-resonance circuit is isolated from other circuits through the PCB, the electromagnetic interference of the components of the biasing circuit on the high-frequency transmission line is reduced to the greatest extent.

Description

Technical Field

[0001] The present application relates to the field of radio frequency / microwave technology, and in particular to a bias circuit board. Background Art

[0002] Power amplifiers are widely used in various wireless communication devices and electronic systems. As an important component in wireless transmitters, all communication indicators need to meet strict requirements. With the promotion of 5G technology, the bandwidth of power amplifiers has begun to attract attention, and it is required to design ultra-wideband power amplifiers with good performance. However, the performance of a power amplifier depends on the design of the bias circuit. The power amplifier needs to obtain energy from the DC power supply through the bias circuit to amplify the input signal. Therefore, the bias circuit becomes a key link in the design of ultra-wideband power amplifiers. In the ultra-wideband power amplifier bias circuit, the DC power supply is connected to the power amplifier tube through a microstrip line network to provide it with a suitable static operating point. At the same time, a path from RF to ground is required so that the bias circuit has good RF small reactance to ground performance. In order to make the power amplifier bias circuit have good RF to ground performance, that is, starting from the node connected to the RF capacitor in the bias circuit, the impedance is very small in the direction of the power supply, which is equivalent to equivalent grounding for the RF signal.

[0003] The existing bias circuits that can provide ultra-wideband for amplifiers usually adopt two design methods. One is to use a conical inductor directly to the high-frequency feeder, and optimize the inductance characteristics by adjusting the winding parameters of the conical inductor, and change the resonant frequency to make the working frequency band develop in the direction of lower frequency or higher frequency; the other is to use a multi-stage voltage-stabilized bias circuit composed of resistors, inductors, capacitors and transistors, and control the stable output of the bias voltage through a voltage-stabilized circuit composed of multiple resistors to enhance the amplifier's quiescent current and improve system compatibility. Among them, in the application of high-frequency RF modules, due to the high sensitivity of the active devices in the high-frequency RF modules, the stability requirements of their bias circuits are high. The fluctuation of the current in the bias circuit will cause irreversible damage to the active devices, especially the broadband power amplifier (the instability of the bias circuit current will cause overcurrent in the amplifier, and even directly damage the amplifier). Summary of the invention

[0004] The present application provides a bias circuit board to solve the technical problem of current fluctuation in the bias circuit of a power amplifier in the prior art.

[0005] In a first aspect, an embodiment provides a bias circuit board, which is a double-sided wiring PCB circuit board, one side of the PCB circuit board is a first circuit panel, and the other side is a second circuit panel;

[0006] The bias circuit board is provided with a bias circuit and a high-frequency transmission line for connecting to a power amplifier, and the bias circuit is used to provide a static operating current to the power amplifier; the bias circuit includes a bias connection terminal, a DC power supply connection terminal, a self-resonant circuit, a decoupling filter circuit, an amplification circuit, an isolation circuit, a power sharing circuit and a work holding circuit;

[0007] The bias connection end is used to connect to the output end of the power amplifier through the high-frequency transmission line;

[0008] The DC power supply connection terminal is used for inputting a DC power supply;

[0009] The self-resonant circuit is connected to the isolation circuit and the bias connection end respectively; the self-resonant circuit is used to curb the backflow of the electrical signal output by the power amplifier and also prevent the leakage of high-frequency signal energy;

[0010] The decoupling filter circuit is connected to the self-resonant circuit; the decoupling filter circuit is used to reduce the Q value of the self-resonant circuit;

[0011] The power sharing circuit is connected to the DC power supply connection terminal and the isolation circuit respectively; the power sharing circuit is used to share the output power of the DC power supply;

[0012] The work holding circuit is connected to the DC power supply connection terminal and the amplifier circuit respectively; the work holding circuit is used to provide a stable DC power supply for the amplifier circuit;

[0013] The amplifying circuit is connected to the isolation circuit, and the amplifying circuit is used to provide a stable static operating current to the power amplifier;

[0014] The isolation circuit comprises an isolation transistor, the base of the isolation transistor is connected to the amplifier circuit, the collector of the isolation transistor is connected to the self-resonant circuit, and the emitter of the isolation transistor is connected to the power sharing circuit; the isolation circuit is used to suppress the fluctuation of the output current signal of the amplifier circuit caused by the change of the internal resistance of the power amplifier, so as to ensure the constancy of the static working current provided to the power amplifier;

[0015] The bias connection terminal, the self-resonant circuit and the high-frequency transmission line of the bias circuit are arranged on the first circuit panel side;

[0016] The decoupling filter circuit, the amplifying circuit, the isolating circuit, the power sharing circuit and the work holding circuit of the bias circuit are arranged on the second circuit panel side.

[0017] In one embodiment, the amplifying circuit includes an amplifying transistor, a resistor R10 and a resistor R11;

[0018] One end of the resistor R10 is connected to the collector of the amplifying transistor, and the other end is connected to the DC power supply connection end;

[0019] One end of the resistor R11 is connected to the emitter of the amplifying transistor, and the other end is grounded;

[0020] The base of the amplifying transistor is connected to the working holding circuit, and the emitter of the amplifying transistor is connected to the base of the isolating transistor; wherein the amplifying transistor is an NPN transistor, and the isolating transistor is a PNP transistor.

[0021] In one embodiment, the amplifying transistor and the isolating transistor are arranged side by side on the second circuit panel.

[0022] In one embodiment, the self-resonant circuit includes an inductor L1, an inductor L2, an inductor L3 and a resistor R1;

[0023] The inductor L1, the inductor L2 and the inductor L3 are connected in series in sequence, one end of the series connection is connected to the collector of the isolation transistor, and the other end of the series connection is connected to the bias connection end;

[0024] The two ends of the resistor R1 are connected to the two ends of the inductor L3 respectively;

[0025] The self-resonant frequency of the inductor L1 is greater than the self-resonant frequency of the inductor L2 and / or the self-resonant frequency of the inductor L2 is greater than the self-resonant frequency of the inductor L3; and the bias connection terminal is arranged on the high-frequency transmission line.

[0026] In one embodiment, the decoupling filter circuit includes a resistor R3 and a capacitor C2; the resistor R3 and the capacitor C2 are connected in series, one end of the series connection is connected to the collector of the isolation transistor, and the other end of the series connection is grounded; the decoupling filter circuit also includes a resistor R2 and a capacitor C1; the resistor R2 and the capacitor C1 are connected in series, one end of the series connection is connected to one end of the inductor L2, and the other end of the series connection is grounded.

[0027] In one embodiment, there is no ground copper mesh under the second circuit panel.

[0028] In one embodiment, the power sharing circuit includes resistor R4, resistor R5, resistor R6 and resistor R7; resistor R4, resistor R5, resistor R6 and resistor R7 form a resistor bridge, a pair of diagonal connection ends of the resistor bridge are electrically connected, and the other pair of diagonal connection ends are respectively connected to the DC power supply connection end and the emitter of the isolation transistor; on the second circuit panel, each resistor of the resistor bridge is arranged on the same side of the amplifying transistor and the isolation transistor.

[0029] In one embodiment, the work holding circuit includes a resistor R8 and a resistor R9; one end of the resistor R9 is connected to the power supply connection end, and the other end is connected to the base of the amplifying transistor; one end of the resistor R8 is grounded, and the other end is connected to the base of the amplifying transistor.

[0030] In one embodiment, the work holding circuit further includes a capacitor C3; one end of the capacitor C3 is connected to the power supply connection end, and the other end of the capacitor C3 is connected to the base of the amplifying transistor.

[0031] In one embodiment, a DC blocking capacitor is provided on the high frequency transmission line.

[0032] According to the bias circuit board of the above embodiment, the high-frequency transmission line and the self-resonant circuit of the bias circuit are isolated from other circuits through the PCB circuit board, thereby minimizing the electromagnetic interference of the bias circuit's own components on the high-frequency transmission line. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A circuit diagram of an ultra-wideband power amplifier bias circuit;

[0034] Figure 2 A schematic diagram of a bias circuit having a series RL parallel structure;

[0035] Figure 3 is a circuit diagram of a bias circuit in an embodiment;

[0036] Figure 4 is a circuit diagram of a bias circuit in another embodiment;

[0037] Figure 5 is a schematic diagram of side A of a bias circuit board in one embodiment;

[0038] Figure 6 Schematic diagram of side B of a bias circuit board in one embodiment. DETAILED DESCRIPTION

[0039] The present application is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are intended to enable the present application to be better understood. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, and methods. In some cases, some operations related to the present application are not shown or described in the specification, in order to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0040] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0041] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0042] The bias circuit is an external additional circuit used to ensure that the emitter junction of the transistor inside the amplifier is forward biased and the collector junction is reverse biased. Only when it is powered normally can the amplifier accurately and undistortedly amplify the signal voltage. Generally, the bias circuit cannot reach the Hz level in the low-frequency area, and can only reach about 4-6GHz in the high-frequency area, and the high-frequency loss is too large. The ultra-wideband bias circuit must be able to provide a normal operating voltage difference for the amplifier, and it must not bring too much insertion loss to the ultra-wideband amplifier due to the characteristics of the device itself. The current bias circuit exists in two forms. A small part of it is that the manufacturer directly adds a bias circuit to the internal structure of the amplifier, and only needs to add a suitable DC power supply externally. This design is simple and convenient, but the scope of application is small and the bandwidth is narrow; the other part is that the manufacturer is not responsible for the bias circuit design of the amplifier. At this time, it is necessary to use an external bias circuit to carry a high-frequency transmission line to provide energy for the amplifier. This circuit design has a wide range of applications, but the DC signal will also affect the high-frequency signal, increase the device insertion loss, and reduce the amplifier gain.

[0043] Amplifiers with ultra-wideband characteristics generally do not have internal bias circuits, and additional bias circuits need to be designed to provide them with bias voltages that can work properly. Series inductors and parallel capacitors have different self-resonance characteristics, and resistors have the characteristics of voltage division to stabilize the circuit and reduce the Q value of the tuning loop. Ultra-wideband bias circuits can be realized by combining different devices. Please refer to Figure 1 This is a circuit diagram of an ultra-wideband power amplifier bias circuit, including a DC power supply, a filter capacitor, a microstrip line network, and a resistance reduction resistor. The DC power supply is connected to the first end of the microstrip line network, and the second end of the microstrip line network is connected to the power supply end of the power amplifier. The microstrip line network includes at least one microstrip line connected in series. The microstrip line in the microstrip line network is also grounded via a filter capacitor C. A resistance reduction resistor R is connected in parallel between the first end and the second end of the microstrip network. Please refer to Figure 2 , is a schematic diagram of a bias circuit with a series RL parallel structure. W / L represent the length and width of the microstrip line respectively. Terminal Term1 represents the impedance port from the node connected to the RF capacitor C to the DC power supply. During software simulation, the impedance at this port can be measured to determine whether the RF achieves a small reactance characteristic to the ground. For RF signals, the DC power supply is equivalent to grounding. Figure 2 In the figure, it is represented as grounding. The impedance reduction resistor R is connected in parallel with the microstrip line TL1 and then connected to one end of the RF capacitor C. The other end of the RF capacitor C is grounded. The three together constitute a part of the bias circuit of the ultra-wideband power amplifier. However, the general ultra-wideband bias circuit is prone to bring large insertion loss to the amplifier in the high frequency range of 4-6GHz, and it cannot work normally in the higher frequency band, and it cannot reach the Hz region in the low frequency band. This parallel resistor is placed on both sides of the microstrip line to reduce the parallel resonance in the pure reactance network. The total impedance value of the bias circuit decreases as the parallel resistance value decreases, thereby achieving good performance of high-frequency signals to the ground within the ultra-wideband, and completing an ultra-wideband bias circuit. However, this bias cannot meet the bandwidth requirements of various RF front-end amplifiers. The low frequency cannot reach the Hz level, and the high frequency can only reach 4-6GHz. In addition, the loss is too large, and the normal working bandwidth is too narrow, so it cannot be used in large quantities in the actual production of measuring instruments.

[0044] Please refer to Figure 3, is a circuit diagram of a bias circuit in an embodiment, including a bias circuit 100 and a power amplifier 200. In order to improve the bandwidth, the bias circuit 100 provides a static operating current to the power amplifier 200, and the bias circuit 100 is used to provide a static operating current to the power amplifier 200. The bias circuit 100 includes a bias connection terminal, a DC power connection terminal, a self-resonant circuit 1, a decoupling filter circuit 2, a transistor circuit 3, a power sharing circuit 4 and a work holding circuit 5. The transistor circuit 3 includes a transistor Q1. The bias connection terminal is used to connect to the output terminal of the power amplifier 200, and the DC power connection terminal is used for the input of a DC power supply 6. The self-resonant circuit 1 is respectively connected to the second pole of the transistor Q1 and the bias connection terminal. The self-resonant circuit 1 is used to curb the backflow of the AC signal output by the power amplifier 200, and also prevent the leakage of high-frequency signal energy. The decoupling filter circuit 2 is connected to the self-resonant circuit 1. The decoupling filter circuit 2 is used to reduce the Q value of the self-resonant circuit 1. The power sharing circuit 4 is connected to the DC power supply connection terminal and the second electrode of the transistor Q1 respectively. The power sharing circuit 4 is used to share the output power of the DC power supply 6. The work holding circuit 5 is connected to the DC power supply connection terminal and the base of the transistor Q1 respectively. The work holding circuit 5 is used to ensure that the emitter junction of the transistor Q1 is forward biased and the collector junction of the transistor Q1 is reverse biased, so that the transistor Q1 works stably, thereby providing a stable static working current.

[0045] Based on the above bias circuit, it should be pointed out that when it comes to the field of RF and microwave technology, Figure 3 The power amplifier 200 indicated in the figure is a device under test, which may be a low-frequency power amplifier or other active device. There are many types of devices under test, but there is uncertainty (the electrical parameters of the device under test cannot be determined). Therefore, when different devices under test (power amplifiers 200) are connected, their internal resistances are different. When the entire power amplifier (including the bias circuit) works normally, the equivalent resistance connected to the collector of the transistor Q1 (the equivalent resistance of the self-resonant circuit 1) will change, thereby causing the amplification of the transistor Q1 to fluctuate, and the amplification fluctuation may cause damage to the device under test (power amplifier 200).

[0046] Briefly describe the reasons for the fluctuations, such as Figure 3 As shown, V R8 (The voltage across resistor R8) is equal to V be (the voltage between the transistor base and collector) and V R1 (the voltage of the self-resonant circuit 1 as an equivalent resistor), that is:

[0047] V R8 =V be + V R1 ;

[0048] The above voltage equation is always valid. When different devices under test are connected, the self-resonant circuit 1 acts as an equivalent resistor, and its equivalent resistance value changes with the internal resistance value of the device under test. R1 will change accordingly;

[0049] V R1 Changes occur, V ce (the voltage between the transistor emitter and collector) will also change, and then I be (the current between the transistor base and collector) and I ce (The current between the emitter and collector of the transistor) will also change, causing a chain of current changes that may cause damage to the device under test.

[0050] Based on the above reasons, in order to ensure the stability of the bias circuit current, in the embodiment of the present application, two cascaded amplifier circuits are set up on the basis of the original bias circuit, and the secondary amplifier circuit is used as an isolation circuit to ensure that the primary amplifier circuit will not produce current fluctuations due to changes in the internal resistance of the device under test, so as not to be affected by reverse interference from the device under test, thereby improving the reliability and stability of the bias circuit, and further ensuring that a stable static operating current is provided to the power amplifier.

[0051] Furthermore, in one embodiment of the present application, a bias circuit board is disclosed, in which the self-resonant circuit of the bias circuit is isolated from other circuits through a PCB circuit board to minimize the electromagnetic interference of the bias circuit's own components on the high-frequency transmission line.

[0052] Embodiment one:

[0053] Please refer to Figure 4, is a circuit diagram of a bias circuit in another embodiment, wherein the bias circuit 100 is used to provide a static operating current to the power amplifier 200. The bias circuit 100 includes a bias connection terminal, a DC power connection terminal, a self-resonant circuit 1, a decoupling filter circuit 2, an amplifying circuit 3, a DC voltage source 6, an isolation circuit 7, a power sharing circuit 4 and a work holding circuit 5. The bias connection terminal is used to connect to the output terminal of the power amplifier 200, and the DC power connection terminal is used for the input of a DC power supply. The DC voltage source 6 is used to output a DC power supply to the DC power connection terminal. The self-resonant circuit 1 is connected to the isolation circuit 7 and the bias connection terminal respectively, and the self-resonant circuit 1 is used to curb the backflow of the electrical signal output by the power amplifier 200, and also prevent the leakage of high-frequency signal energy. The decoupling filter circuit 2 is connected to the self-resonant circuit 1, and the decoupling filter circuit 2 is used to reduce the Q value of the self-resonant circuit 1. The power sharing circuit 4 is connected to the DC power connection terminal and the isolation circuit 7 respectively, and the power sharing circuit 4 is used to share the output power of the DC power supply. The work holding circuit 5 is connected to the DC power supply connection terminal and the amplifier circuit 3 respectively, and the work holding circuit 5 is used to provide a stable DC power supply for the amplifier circuit 3. The amplifier circuit 3 is connected to the isolation circuit 7, and the amplifier circuit is used to provide a stable static working current to the power amplifier 200. The isolation circuit 7 includes an isolation transistor Q20, the base of the isolation transistor Q20 is connected to the amplifier circuit 3, the collector of the isolation transistor Q20 is connected to the self-resonant circuit 1, and the emitter of the isolation transistor Q20 is connected to the power sharing circuit 4. The isolation circuit 4 is used to suppress the fluctuation of the output current signal of the amplifier circuit caused by the change of the internal resistance of the power amplifier 200, so as to ensure the constancy of the static working current provided to the power amplifier 200.

[0054] In one embodiment, the amplifier circuit 3 includes an amplifier transistor Q10, a resistor R10 and a resistor R11. One end of the resistor R10 is connected to the collector of the amplifier transistor Q10, and the other end is connected to the DC power supply connection end. One end of the resistor R11 is connected to the emitter of the amplifier transistor Q10, and the other end is grounded. The base of the amplifier transistor Q10 is connected to the work holding circuit 5, and the emitter of the amplifier transistor Q10 is connected to the base of the isolation transistor Q20. In one embodiment, the amplifier transistor Q20 is an NPN transistor, and the isolation transistor Q20 is a PNP transistor.

[0055] In one embodiment, the self-resonant circuit 1 includes an inductor L1, an inductor L2, an inductor L3 and a resistor R1. The inductor L1, the inductor L2 and the inductor L3 are connected in series in sequence, one end of the series connection is connected to the collector of the isolation transistor Q20, and the other end of the series connection is connected to the bias connection end. The two ends of the resistor R1 are respectively connected to the two ends of the inductor L3, wherein the self-resonant frequency of the inductor L1 is greater than the self-resonant frequency of the inductor L2 and / or the self-resonant frequency of the inductor L2 is greater than the self-resonant frequency of the inductor L3.

[0056] In one embodiment, the decoupling filter circuit 2 includes a resistor R3 and a capacitor C2, the resistor R3 and the capacitor C2 are connected in series, one end of the series connection is connected to the collector of the isolation transistor Q20, and the other end of the series connection is grounded. The decoupling filter circuit also includes a resistor R2 and a capacitor C1, the resistor R2 and the capacitor C1 are connected in series, one end of the series connection is connected to the common connection end of the inductor L2 and the inductor L3, and the other end of the series connection is grounded.

[0057] In one embodiment, the power sharing circuit 4 includes a resistor R4, a resistor R5, a resistor R6 and a resistor R7; the resistors R4, R5, R6 and R7 form a resistor bridge, a pair of diagonal connection ends of the resistor bridge are electrically connected, and the other pair of diagonal connection ends are respectively connected to the DC power supply connection end and the emitter of the isolation transistor Q20.

[0058] In one embodiment, the work holding circuit 5 includes a resistor R8 and a resistor R9, one end of the resistor R9 is connected to the power connection terminal, and the other end is connected to the base of the amplifier transistor Q10, one end of the resistor R8 is grounded, and the other end is connected to the base of the amplifier transistor Q10. In one embodiment, the work holding circuit 5 also includes a capacitor C3, one end of the capacitor C3 is connected to the power connection terminal, and the other end is connected to the base of the amplifier transistor Q10.

[0059] In one embodiment of the present application, a power amplifier is also disclosed, including the bias circuit as described above.

[0060] In one embodiment of the present application, the bias circuit utilizes a combination of three inductors in series, a bypass capacitor and a resistor, and a triode amplifier circuit of a DC source to realize an ultra-wideband bias circuit. Among them, one end of the inductor L1 is mounted on the high-frequency transmission line, which can prevent the leakage of high-frequency signal energy and curb the backflow of AC signals. One end of the inductor L2 is connected to the other end of L1 in a series connection. The effective electrical length between the inductor L2 and the inductor L1 is not easy to be too long, otherwise the parasitic parameters will be increased, affecting the inductor performance. The inductor series connection can not only reduce the coupling effect between the inductor and the PCB, but also increase the inductor resonance bandwidth, curb signal shunting, and prevent energy leakage. After the bypass capacitor C1 and the resistor R2 are connected in series, a decoupling filter circuit is formed, one end is connected to one side of L2, and the other end is grounded. The resistor R2 can not only reduce the Q value in the tuning loop, but also reduce the frequency imbalance caused by the interaction between the PCB circuit board and the coupling capacitor C1. The capacitor C1 can filter signal clutter and remove power supply noise. Inductor L3 is still connected in series with inductors L1 and L2 and connected to one end of L2. Inductor L3 can make the resonant frequency of the bias circuit reach the low-frequency area Hz level, and the resistor R1 is connected in parallel at both ends of inductor L3 to shunt it, protecting the current value in inductor L3 for stable output. The self-resonant frequency of inductor L1 is higher, and the self-resonant frequency of inductor L2 is lower than that of L1. Inductor L3 resonates in the low-frequency domain. The series connection of L1, L2, and L3 realizes the common resonance from the low-frequency band to the high-frequency band, broadens the resonant frequency band, realizes ultra-wideband resonance, and effectively suppresses the leakage of the amplifier transmission signal. After bypass capacitor C2 and resistor R3 are connected in series, another decoupling filter circuit is formed, one end of which is connected to the other end of inductor L3, and the other end is grounded together with the decoupling filter circuit composed of capacitor C1 and resistor R2. Resistor R3 is also used to reduce the Q value in the tuning loop and reduce the frequency detuning caused by the interaction between the PCB circuit board and the coupling capacitor C2. Capacitor C2 is also used to filter signal clutter and remove power supply noise. Resistors R4 and R5 are connected in parallel, and resistors R6 and R7 are connected in parallel. Then, the parallel resistors are connected in series, one end of which is connected to the isolation transistor, and the other end is connected to the positive collector of the DC power supply. This resistor series-parallel connection method can not only control the resistance size to remain unchanged, but also improve the ability of the resistor to share the power output power of the power supply to meet the needs of overall signal amplification. One end of capacitor C3 is connected to the base of the amplifying transistor, and the other end is connected to the positive pole of the power supply to filter and remove noise from the amplifying circuit. One end of resistor R8 is connected to the base of the amplifying transistor, and the other end is grounded. By changing the value of R8, the power supply noise signal is suppressed, the stability of the normal operation of the amplifying transistor Q10 is improved, and the operating frequency and maximum current requirements of the inductor component are met. Resistor R9 is connected in parallel with capacitor C3. Resistor R9 acts as a voltage divider to ensure that the emitter junction of the amplifying transistor is forward biased, the collector junction is reverse biased, and the bias current of the emitter transistor is stabilized.Looking from the emitter of the amplifier transistor to the DC power supply, the impedance is infinite, which can effectively suppress the transmission of low-frequency AC signals and stabilize the lossless output of the amplifier in the low-frequency area. One end of the resistor R11 is connected to the emitter of the NPN amplifier transistor Q10, and the other end is grounded. It is used as a feedback resistor to suppress the power supply noise signal and improve the stability of the normal operation of the amplifier transistor. One end of the resistor R10 is connected to the collector of the amplifier transistor Q10, and the other end is connected to the positive pole of the DC power supply. It acts as a pull-up resistor to suppress the power supply noise signal and improve the stability of the normal operation of the amplifier transistor. Looking from the collector of the PNP isolation transistor Q20 to the DC power supply, the impedance is infinite, which can effectively suppress the transmission of low-frequency AC signals and stabilize the lossless output of the amplifier in the low-frequency area. The entire bias circuit combines the DC voltage source, resistor R8, resistor R9, resistor R10, resistor R11, capacitor C3 and the emitter transistor Q10 to form the first-stage amplifier circuit, and R11 acts as a DC feedback resistor, which makes the first-stage amplifier circuit have a stable Q point. The entire bias circuit then forms a second-stage amplifier circuit with a DC voltage source, resistors R4, R5, R6, R7 and an isolation transistor Q20. Since the emitter of the amplifier transistor in the first-stage amplifier circuit (amplifier circuit) is directly connected to the base of the isolation transistor in the second-stage amplifier circuit (isolation circuit), the base of the amplifier transistor clamps the emitter of the isolation transistor. The combination of the first-stage amplifier circuit and the second-stage amplifier circuit will make the entire bias circuit no longer affected by temperature and active devices connected to the output port (amplifier internal resistance changes), but only related to the resistance values ​​of the resistors R4, R5, R6, R7, R8, R9, R10 and R11 of its own circuit, which will greatly improve the stability of the bias circuit.

[0061] The bias circuit disclosed in the application embodiment is used to provide a static working current to the power amplifier, and the bias circuit includes a self-resonant circuit, a decoupling filter circuit, an amplifier circuit, an isolation circuit, a power sharing circuit and a work holding circuit. The self-resonant circuit is used to curb the backflow of the electrical signal output by the power amplifier, the decoupling filter circuit is used to reduce the Q value of the self-resonant circuit, the power sharing circuit is used for voltage division, the work holding circuit is used to provide a DC power supply for the amplifier circuit, the amplifier circuit is used to provide a stable static working current to the power amplifier, and the isolation circuit is used to suppress the fluctuation of the output current signal of the amplifier circuit caused by the change of the internal resistance of the power amplifier. The ultra-wideband bias circuit is realized by an active amplifier circuit, and an isolation circuit is added to ensure that the static working current output to the power amplifier will not fluctuate when its internal resistance changes, so as to improve the reliability, stability and safety of the power amplifier. Since the ultra-wideband bias circuit is realized by a triode amplifier circuit with a DC source, it can provide a normal working voltage difference for the power amplifier, and will not bring too much device insertion loss to the power amplifier, so that the gain of the power amplifier is improved. The bias circuit can use different packaging technologies to achieve resonance suppression at different frequencies, expand the resonance bandwidth, bypass capacitors for decoupling and noise filtering, resistors to reduce the circuit resonance Q value, and add transistors to the DC power supply to prevent the backflow of low-frequency AC signals, forming a bias amplifier circuit to ensure the maximum working current configuration of the inductor. The circuit structure is simple and can be completed with ordinary inductors and capacitors. The circuit has high stability, high fault tolerance, low cost, and is conducive to large-scale development.

[0062] Embodiment two:

[0063] Please refer to Figure 5 and Figure 6, is a schematic diagram of the structure of the A side and the B side of the bias circuit board in an embodiment. In one embodiment of the present application, a bias circuit board is disclosed, on which the bias circuit board is provided with the bias circuit as described in the first embodiment and a high-frequency transmission line connected to the power amplifier. The bias circuit board adopts a double-sided design, which is respectively a first circuit panel (bias circuit board A side) and a second circuit panel (bias circuit board A side). The bias connection terminal, self-resonant circuit and high-frequency transmission line of the bias circuit are arranged on the first circuit panel side, and the decoupling filter circuit, amplification circuit, isolation circuit, power sharing circuit and working holding circuit of the bias circuit are arranged on the second circuit panel side. In this way, the inductance of the bias circuit is mainly distributed on the surface layer, on the same side as the active device. Different grounding positions and different metal via positions in PCB circuit boards used for radio frequency and microwaves will change the capacitance distribution in the PCB. In the embodiment of the present application, the positions of the metal vias on the bias circuit board are arranged in a direction perpendicular to the high-frequency transmission line to minimize the electromagnetic interference of the components themselves on the high-frequency transmission line, and the lower area of ​​all pad positions is set to an irregular bare ground without a copper plate, in order to prevent the formation of coupling capacitance between the upper pad and the lower copper plate, which affects the transmission of the amplifier's high-frequency signal. Figure 6 As shown, in the circuit layout design of the second circuit panel, the transistors (Q10 and Q20) and the voltage divider resistors are mainly distributed on the bottom layer. One is to isolate the interference of the DC source on the AC signal through the intermediate dielectric layer of the PCB circuit board. The other is because the layout of the PCB circuit board is always limited. The RF devices are placed on the surface as much as possible, and the rest of the digital analog hardware is placed on another layer to reduce the layout pressure on the surface. The bias circuit in the embodiment of the present application has a low frequency of Hz level and a high frequency of 30GHz. It has an ultra-wide bandwidth, low loss, high system fault tolerance, low cost, and is easy to integrate into high-frequency transmission lines, which is conducive to the composition of precision devices. It can be developed on a large scale and has a wide range of applications. The overall structure and combination mode of the bias circuit are simple. Inductors are connected in series and different packaging technologies are used to achieve resonance suppression at different frequencies, expand the resonance bandwidth, bypass capacitors for decoupling and filtering noise, and resistors reduce the circuit resonance Q value. A transistor is added to the DC power supply to prevent the backflow of low-frequency AC signals, forming a bias amplifier circuit to ensure the maximum working current configuration of the inductor. At the same time, there is no grounding copper plate in the area below the pad on the PCB circuit board, which is exposed. The circuit structure is simple and can be completed with ordinary inductors and capacitors. The circuit has high stability, high fault tolerance, low cost, and is conducive to large-scale development.

[0064] The bias circuit board disclosed in the embodiment of the present application is a double-sided wiring PCB circuit board, on which a bias circuit and a high-frequency transmission line connected to a power amplifier are arranged, and the bias circuit includes a self-resonant circuit arranged on the first circuit panel side and a decoupling filter circuit, an amplifier circuit, an isolation circuit, a power sharing circuit and a work holding circuit arranged on the second circuit panel. The self-resonant circuit is used to curb the backflow of the electrical signal output by the power amplifier, the decoupling filter circuit is used to reduce the Q value of the self-resonant circuit, the power sharing circuit is used for voltage division, the work holding circuit is used to provide a DC power supply for the amplifier circuit, the amplifier circuit is used to provide a stable static working current to the power amplifier, and the isolation circuit is used to suppress the fluctuation of the output current signal of the amplifier circuit caused by the change of the internal resistance of the power amplifier. Since the self-resonant circuit is isolated from other circuits through the PCB circuit board, the electromagnetic interference of the bias circuit components on the high-frequency transmission line is minimized.

[0065] The above specific examples are used to illustrate the present application, which is only used to help understand the present application and is not intended to limit the present application. For technicians in the technical field to which the present application belongs, they can also make some simple deductions, deformations or substitutions based on the ideas of the present application.

Claims

1. A bias circuit board, characterized in that: A double-sided wiring PCB circuit board, one side of the PCB circuit board is a first circuit panel, and the other side is a second circuit panel; The bias circuit board is provided with a bias circuit and a high-frequency transmission line for connecting to a power amplifier, and the bias circuit is used to provide a static operating current to the power amplifier; the bias circuit includes a bias connection terminal, a DC power supply connection terminal, a self-resonant circuit, a decoupling filter circuit, an amplification circuit, an isolation circuit, a power sharing circuit and a work holding circuit; The bias connection end is used to connect to the output end of the power amplifier through the high-frequency transmission line; The DC power supply connection terminal is used for inputting a DC power supply; The self-resonant circuit is connected to the isolation circuit and the bias connection end respectively; the self-resonant circuit is used to curb the backflow of the electrical signal output by the power amplifier and also prevent the leakage of high-frequency signal energy; The decoupling filter circuit is connected to the self-resonant circuit; the decoupling filter circuit is used to reduce the Q value of the self-resonant circuit; The power sharing circuit is connected to the DC power supply connection terminal and the isolation circuit respectively; the power sharing circuit is used to share the output power of the DC power supply; The work holding circuit is connected to the DC power supply connection terminal and the amplifier circuit respectively; the work holding circuit is used to provide a stable DC power supply for the amplifier circuit; The amplifying circuit is connected to the isolation circuit, and the amplifying circuit is used to provide a stable static operating current to the power amplifier; The isolation circuit comprises an isolation transistor, the base of the isolation transistor is connected to the amplifier circuit, the collector of the isolation transistor is connected to the self-resonant circuit, and the emitter of the isolation transistor is connected to the power sharing circuit; the isolation circuit is used to suppress the fluctuation of the output current signal of the amplifier circuit caused by the change of the internal resistance of the power amplifier, so as to ensure the constancy of the static working current provided to the power amplifier; The bias connection terminal, the self-resonant circuit and the high-frequency transmission line of the bias circuit are arranged on the first circuit panel side; The decoupling filter circuit, the amplifying circuit, the isolating circuit, the power sharing circuit and the work holding circuit of the bias circuit are arranged on the second circuit panel side.

2. The bias circuit board according to claim 1, characterized in that: The amplifying circuit includes an amplifying transistor, a resistor R10 and a resistor R11; One end of the resistor R10 is connected to the collector of the amplifying transistor, and the other end is connected to the DC power supply connection end; One end of the resistor R11 is connected to the emitter of the amplifying transistor, and the other end is grounded; The base of the amplifying transistor is connected to the working holding circuit, and the emitter of the amplifying transistor is connected to the base of the isolating transistor; wherein the amplifying transistor is an NPN transistor, and the isolating transistor is a PNP transistor.

3. The bias circuit board according to claim 2, characterized in that: The amplifying transistor and the isolating transistor are arranged side by side on the second circuit panel.

4. The bias circuit board according to claim 2, characterized in that: The self-resonant circuit includes an inductor L1, an inductor L2, an inductor L3 and a resistor R1; The inductor L1, the inductor L2 and the inductor L3 are connected in series in sequence, one end of the series connection is connected to the collector of the isolation transistor, and the other end of the series connection is connected to the bias connection end; The two ends of the resistor R1 are connected to the two ends of the inductor L3 respectively; The self-resonant frequency of the inductor L1 is greater than the self-resonant frequency of the inductor L2 and / or the self-resonant frequency of the inductor L2 is greater than the self-resonant frequency of the inductor L3; and the bias connection terminal is arranged on the high-frequency transmission line.

5. The bias circuit board according to claim 2, characterized in that: The decoupling filter circuit includes a resistor R3 and a capacitor C2; the resistor R3 and the capacitor C2 are connected in series, one end of the series connection is connected to the collector of the isolation transistor, and the other end of the series connection is grounded; the decoupling filter circuit also includes a resistor R2 and a capacitor C1; the resistor R2 and the capacitor C1 are connected in series, one end of the series connection is connected to one end of the inductor L2, and the other end of the series connection is grounded.

6. The bias circuit board according to claim 5, characterized in that: There is no ground copper mesh under the second circuit panel.

7. The bias circuit board according to claim 2, characterized in that: The power sharing circuit includes resistor R4, resistor R5, resistor R6 and resistor R7; resistor R4, resistor R5, resistor R6 and resistor R7 form a resistor bridge, a pair of diagonal connection ends of the resistor bridge are electrically connected, and the other pair of diagonal connection ends are respectively connected to the DC power supply connection end and the emitter of the isolation transistor; on the second circuit panel, each resistor of the resistor bridge is arranged on the same side of the amplifying transistor and the isolation transistor.

8. The bias circuit board according to claim 2, characterized in that: The work holding circuit includes a resistor R8 and a resistor R9; one end of the resistor R9 is connected to the power supply connection end, and the other end is connected to the base of the amplifying transistor; one end of the resistor R8 is grounded, and the other end is connected to the base of the amplifying transistor.

9. The bias circuit board according to claim 8, characterized in that: The work holding circuit further includes a capacitor C3; one end of the capacitor C3 is connected to the power supply connection end, and the other end of the capacitor C3 is connected to the base of the amplifying transistor.

10. The bias circuit board according to claim 2, characterized in that: The high frequency transmission line is provided with a DC blocking capacitor.

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