WO2023050990A1

WO2023050990A1 - Esd protection circuit of radio frequency power amplifier

Info

Publication number: WO2023050990A1
Application number: PCT/CN2022/108103
Authority: WO
Inventors: 彭艳军; 宣凯; 郭嘉帅
Original assignee: 深圳飞骧科技股份有限公司
Priority date: 2021-09-29
Filing date: 2022-07-27
Publication date: 2023-04-06
Also published as: CN215990207U

Abstract

An ESD protection circuit (100) of a radio frequency power amplifier, comprising an input end (RFin), an output end (RFout), a transistor (Q0), a bias circuit (1), and a first ESD protection circuit (EC1). A base of the transistor (Q0) is connected to the input end (RFin), an emitter is grounded, and a collecting electrode is separately connected to the output end (RFout) and a circuit voltage source (Vcc); the bias circuit (1) is connected between the base and a reference voltage source (Vreg) of the transistor (Q0) in series; a base (B) of a first transistor (Q1) of the first ESD protection circuit (EC1) is configured to be open, a collecting electrode (C) is connected to the circuit voltage source (Vcc), and an emitter (E) is connected to a positive electrode of a first diode (D1); a positive electrode of the first diode (D1) is grounded; a positive electrode of a second diode (D2) is grounded, and a negative electrode is connected to the collecting electrode (C) of the first transistor (Q1); a positive electrode of a third diode (D3) is grounded, and a negative electrode is connected to the collecting electrode of the first transistor (Q1). The ESD protection circuit (100) of the radio frequency power amplifier occupies a small chip area, and has good reliability and lower cost.

Description

RF Power Amplifier ESD Protection Circuit

technical field

The utility model relates to the technical field of radio frequency integrated circuit design, in particular to a radio frequency power amplifier ESD protection circuit of a mobile communication device.

Background technique

GaAs-based HBT transistors are often used in the design of radio frequency power amplifier. However, the HBT device manufactured by the GaAs process has a stacked vertical structure, and the thickness of the emitter and base epitaxial layers is on the order of 100 nanometers. At the same time, the small surface area of the HBT device makes it difficult to dissipate heat, making the HBT device very prone to electrostatic breakdown. The GaAs thin film resistor is isolated on the top layer of the dielectric film, which is not conducive to heat dissipation, and the GaAs thin film resistor is also prone to electrostatic breakdown. In circuit design, an electrostatic discharge (ESD) protection circuit must be added to protect GaAs components and improve reliability.

The ESD protection circuit of the RF power amplifier of the related art is shown in Figure 1, a plurality of diodes are connected in series between the collector of the transistor and the ground, and the ESD protection circuit of the diode series form requires 6-8 diodes with a certain area to be cascaded. Power RF power amplifiers, due to the large output voltage swing, even need 10-12 diodes. These ESD protection diodes occupy a large chip area. When a high voltage is present on the collector, the diode in series will conduct, clamping the collector voltage to a safe voltage range. In order to improve a good ESD protection capability, the area of the diode is required to be large enough to provide a strong discharge capability. At the same time, there is a large output voltage swing at the collector output terminal of the radio frequency power amplifier in the related art, and the ESD protection circuit connected in series must be able to withstand the swing voltage without conducting. According to the size of the output voltage swing, n ESD protection diodes need to be connected in series to ensure that the output voltage is not affected. The bias reference voltage Vreg of the amplifying tube also requires an ESD protection circuit, using m series-connected ESD protection diodes and at least one reverse-biased diode to implement forward and reverse ESD protection for the Vreg voltage. The multiple protection diodes of the ESD protection circuit occupy a large chip area, and the diode layout of the ESD protection circuit is shown in Figure 2, which leads to an increase in chip cost.

In order to reduce the chip area occupied by the ESD protection circuit, thereby reducing the cost of the chip, using an ESD protection circuit with a smaller area is an effective way to solve the above problems.

Utility model content

In view of the deficiencies of the above related technologies, the utility model proposes a radio frequency power amplifier ESD protection circuit with good reliability, small circuit size and low cost, which is applied in wireless communication.

In order to solve the above technical problems, the utility model provides a radio frequency power amplifier ESD protection circuit, including an input terminal, an output terminal, a transistor, a bias circuit and a first ESD protection circuit; the base of the transistor is connected to the input terminal, the emitter of the transistor is connected to ground, and the collector of the transistor is respectively connected to the output terminal and the circuit voltage source; the bias circuit is connected in series between the base of the transistor and the reference voltage source Between; the first ESD protection circuit is connected between the collector of the transistor and ground, for providing electrostatic discharge protection for the transistor;

The first ESD protection circuit includes a first transistor, a first diode, a second diode and a third diode;

The base of the first transistor is set in an open circuit, the collector of the first transistor is connected to the circuit voltage source, and the emitter of the first transistor is connected to the anode of the first diode;

the cathode of the first diode is connected to ground;

The anode of the second diode is connected to ground, and the cathode of the second diode is connected to the collector of the first transistor;

The anode of the third diode is connected to ground, and the cathode of the third diode is connected to the collector of the first transistor.

Preferably, the first ESD protection circuit further includes a fourth diode, the fourth diode is connected in series between the first diode and the ground, and the anode of the fourth diode is connected to to the cathode of the first diode.

Preferably, the RF power amplifier ESD protection circuit further includes a second ESD protection circuit, the second ESD protection circuit is connected between the reference voltage source and ground, and is used to provide electrostatic discharge protection for the bias circuit ; The second ESD protection circuit includes a second transistor, a fifth diode and a sixth diode;

The base of the second transistor is set in an open circuit, the emitter of the second transistor is connected to ground, and the collector of the second transistor is connected to the reference voltage source;

The anode of the fifth diode is connected to ground, and the cathode of the fifth diode is connected to the collector of the second transistor;

The anode of the sixth diode is connected to ground, and the cathode of the sixth diode is connected to the collector of the second transistor.

Preferably, the transistor, the first transistor and the second transistor are all GaAs-based HBT transistors.

Preferably, the transistor, the first transistor and the second transistor are all PNP transistors.

Preferably, the radio frequency power amplifier ESD protection circuit further includes an input impedance matching circuit, and the input impedance matching circuit is a first capacitor connected in series between the input terminal and the bias circuit.

Preferably, the RF power amplifier ESD protection circuit also includes an output impedance matching circuit, the output impedance matching circuit includes an inductor connected in series between the collector of the transistor and the first ESD protection circuit and connected in series with the A second capacitor between the collector of the transistor and the output.

Compared with the prior art, the radio frequency power amplifier ESD protection circuit of the present utility model adopts a transistor with an open base to replace a plurality of series diode circuits in the related art, and utilizes cascaded base-collector PN junctions and The base-emitter PN junction realizes the protection of the current of the forward electrostatic voltage, which improves its reliability; at the same time, the layout is square and the area is small, and it is easy to be placed in the gap of the layout of the main channel layout, thereby reducing the entire RF power The layout area of the ESD protection circuit of the amplifier reduces the cost of the chip.

Description of drawings

Below in conjunction with accompanying drawing, describe the utility model in detail. Through the detailed description in conjunction with the following drawings, the content of the above or other aspects of the present invention will become clearer and easier to understand. In the attached picture:

Fig. 1 is the ESD protection circuit diagram of the radio frequency power amplifier of related art;

Fig. 2 is the ESD protection circuit layout of the radio frequency power amplifier of related art;

Fig. 3 is the circuit diagram of the utility model embodiment one radio frequency power amplifier ESD protection circuit;

FIG. 4 is a layout of an ESD protection circuit for a radio frequency power amplifier according to an embodiment of the present invention.

FIG. 5 is a circuit diagram of an ESD protection circuit of a radio frequency power amplifier according to Embodiment 2 of the present invention.

Detailed ways

The specific embodiment of the utility model will be described in detail below in conjunction with the accompanying drawings.

The specific implementations/embodiments described here are specific specific implementations of the present utility model, and are used to illustrate the concept of the present utility model. Limitations on the scope of utility models. In addition to the embodiments described here, those skilled in the art can also adopt other obvious technical solutions based on the claims of the application and the contents disclosed in the description, and these technical solutions include adopting any obvious changes made to the embodiments described here. The replacement and modified technical solutions are all within the protection scope of the present utility model.

The following descriptions of the various embodiments refer to the accompanying drawings to illustrate specific embodiments in which the present invention can be implemented. The directional terms mentioned in the present invention, such as up, down, front, back, left, right, inside, outside, side, etc., are only directions referring to the attached drawings. Therefore, the directional terms used are used to illustrate and understand the utility model, rather than to limit the utility model.

Please refer to FIG. 3 , which is a circuit diagram of a radio frequency power amplifier ESD protection circuit according to an embodiment of the present invention. The utility model provides a radio frequency power amplifier ESD protection circuit 100, which is a GaAs HBT radio frequency power amplifier designed by a GaAs-based HBT process. The RF power amplifier needs electrostatic discharge (ESD) protection circuit to protect the input, output, power supply and each port of the control circuit. The ESD protection circuit is to protect the core circuit from being damaged by electrostatic high voltage and instantaneous high current. Under normal working conditions, the ESD protection circuit does not need to be opened. When the electrostatic voltage of the port exceeds the turn-on voltage of the ESD protection circuit, the ESD protection circuit is turned on, providing a low-impedance discharge channel, discharging the instantaneous large static current, and reducing the voltage on the port to protect the core circuit. The ESD protection circuit itself must avoid being falsely triggered by the internal noise of the radio frequency chip, resulting in distortion of the radio frequency signal in the core circuit. During normal operation, the influence of the parasitic parameters of the ESD circuit on the core circuit can be ignored.

For GaAs HBT, the mechanism of electrostatic discharge damaging the emitter junction or collector junction of GaAs HBT tube, the PN junction of the diode, the metal connection and the thin film resistance is ultimately due to the thermal effect caused by the large current of electrostatic discharge. Compared with the base-collector PN junction, the GaAs HBT base-emitter PN junction has a higher doping concentration, and the junction resistance is smaller. The thermal effect generated when a large current flows through the emitter junction due to electrostatic discharge is lower than that of the collector junction. , so the emitter junction can withstand a larger electrostatic discharge current. Enhancing the area of the emitter junction and collector junction will increase the ability to withstand electrostatic current, but an excessively large junction area will increase the junction capacitance and affect the impedance of the core circuit. The input terminal of the GaAs HBT RF power amplifier has the electrostatic protection capability of the forward diode because the base-emitter junction of the input amplifier HBT tube itself has the electrostatic protection capability of the forward diode, so it is only necessary to increase the reverse electrostatic protection.

The electrostatic protection of the input terminal of the RF power amplifier of the GaAs-based HBT is usually realized by connecting an inductor in parallel on the input pad PAD. The parallel inductor provides a low-impedance discharge path for ESD, and at the same time completes the input impedance matching without increasing the chip area.

Both the output terminal and the power supply terminal of the RF power amplifier need to add electrostatic protection circuits, often requiring several ESD protection circuits. Reducing the size of each ESD circuit is of great significance to reducing the size of the entire RF power amplifier.

Based on this, the RF power amplifier ESD protection circuit 100 of the present invention includes an input terminal RFin, an output terminal RFout, a transistor Q0, a bias circuit 1 and a first ESD protection circuit EC.

The base of the transistor Q0 is connected to the input terminal RFin, the emitter of the transistor Q0 is connected to ground, and the collector of the transistor Q0 is respectively connected to the output terminal RFout and the circuit voltage source Vcc. The bias circuit 1 is connected in series between the base of the transistor Q0 and the reference voltage source Vreg. The first ESD protection circuit EC is connected between the collector of the transistor Q0 and ground, and is used for providing electrostatic discharge protection for the transistor Q0.

Specifically, in this embodiment, the first ESD protection circuit EC includes a first transistor Q1, a first diode D1, a second diode D2 and a third diode D3.

The base of the first transistor Q1 is set in an open circuit, the collector of the first transistor Q1 is connected to the circuit voltage source Vcc, and the emitter of the first transistor Q1 is connected to the first diode D1 positive pole. The cathode of the first diode D1 is connected to ground.

The anode of the second diode D2 is connected to the ground, and the cathode of the second diode D2 is connected to the collector of the first transistor Q1.

The anode of the third diode D3 is connected to the ground, and the cathode of the third diode D3 is connected to the collector of the first transistor Q1.

In this implementation manner, both the transistor Q0 and the first transistor Q1 are GaAs-based HBT transistors. More preferably, both the transistor Q0 and the first transistor Q1 are PNP transistors.

In the RF power amplifier ESD protection circuit 100 of the present utility model, a first transistor Q1 with an open base is used to replace a plurality of series diode circuits in the related art, and a cascaded base-collector PN junction and base -The emitter PN junction realizes the protection of the current of the forward electrostatic voltage, which improves its reliability. At the same time, the layout is square and the area is small, and it is easy to be placed in the gap of the layout of the main channel, thereby reducing the layout area of the entire radio frequency power amplifier ESD protection circuit 100, thereby effectively reducing the chip cost.

The emitter of the first transistor Q1 is provided with a forward-biased first diode D1 in series, which can withstand a large output voltage swing of the radio frequency power amplifier and further improve reliability.

The protection of the reverse electrostatic voltage and current is realized by two parallel reverse biased diodes (the second diode D2 and the third diode D3), so as to ensure that the transistor Q0 can withstand a large reverse electrostatic current, Circuit reliability is also improved.

Certainly, the radio frequency power amplifier ESD protection circuit 100 of the present invention also includes an input impedance matching circuit, and the input impedance matching circuit is specifically a first capacitor C1 connected in series between the input terminal RFin and the bias circuit 1 .

The radio frequency power amplifier ESD protection circuit 100 also includes an output impedance matching circuit, and the output impedance matching circuit includes an inductor L connected in series between the collector of the transistor Q0 and the first ESD protection circuit EC and an inductor L connected in series with the first ESD protection circuit EC. The second capacitor C2 between the collector of the transistor Q0 and the output terminal RFout.

In addition, the reference voltage provided by the bias reference voltage source Vreg of the transistor Q0 also requires an ESD protection circuit. In this embodiment, the radio frequency power amplifier ESD protection circuit 100 further includes a second ESD protection circuit EC2, the second ESD protection circuit EC2 is connected between the reference voltage source Vreg and ground, and is used for Set circuit 1 to provide electrostatic discharge protection.

In this embodiment, the second ESD protection circuit EC2 includes a second transistor Q2, a fifth diode D5 and a sixth diode D6.

In this implementation test, the second transistors Q2 are all GaAs-based HBT transistors. Specifically, it is a PNP transistor.

The base of the second transistor Q2 is set as an open circuit, the emitter of the second transistor Q2 is connected to the ground, and the collector of the second transistor Q2 is connected to the reference voltage source Vreg.

The anode of the fifth diode D5 is connected to the ground, and the cathode of the fifth diode D5 is connected to the collector of the second transistor Q2.

The anode of the sixth diode D6 is connected to the ground, and the cathode of the sixth diode D6 is connected to the collector of the second transistor Q2.

Since the voltage of the reference voltage source Vreg is stable and its amplitude is smaller than the voltage of the circuit voltage source Vcc, the emitter of the base open-circuit HBT transistor (second transistor Q2) in the second ESD protection circuit EC2 does not need to be connected in series with a diode, as shown in FIG. 4 , It is the layout of the RF power amplifier ESD protection circuit in the embodiment of the present invention. It can be seen that the layout is square and the area is small. It is easy to be placed in the gap of the layout of the main channel layout, thereby reducing the area of the entire layout and reducing the cost of the chip.

The utility model also provides another embodiment, as shown in FIG. 5 , which is a circuit diagram of the ESD protection circuit of the radio frequency power amplifier of the second embodiment of the utility model. This embodiment is basically the same as Embodiment 1 shown in Figure 3, the difference is:

The first ESD protection circuit EC1 further includes a fourth diode D4, the fourth diode D4 is connected in series between the first diode D1 and the ground, and the fourth diode D4 The anode is connected to the cathode of the first diode D1.

The second embodiment is mainly aimed at high-power radio frequency power amplifiers, whose output voltage swing is large. In order to carry a larger voltage swing, the forward electrostatic voltage protection terminal of the first ESD protection circuit EC1 of the collector output of the transistor Q0 is connected in series. Two forward biased diodes, namely a first diode D1 and a fourth diode D4. Although the area of an ESD protection diode has been increased, its area is still much smaller than the area of a plurality of diode series structures of the ESD of the radio frequency power amplifier in the related art, and this structure is set so that the radio frequency power amplification ESD protection of the present utility model The circuit can be applied to the design of a radio frequency power amplifier with greater output power, and has better reliability.

Except for the above differences, other structures and functions are the same, and will not be repeated here.

It should be noted that the various embodiments described above with reference to the accompanying drawings are only used to illustrate the utility model rather than limit the scope of the utility model, those of ordinary skill in the art should understand that without departing from the spirit and scope of the utility model Any modifications or equivalent replacements made to the present utility model under the premise of the present utility model shall be covered within the scope of the present utility model. Further, words appearing in the singular include the plural and vice versa unless the context otherwise requires. Additionally, all or a portion of any embodiment may be utilized with all or a portion of any other embodiment, unless stated otherwise.

Claims

A radio frequency power amplifier ESD protection circuit, comprising an input terminal, an output terminal, a transistor, a bias circuit and a first ESD protection circuit; the base of the transistor is connected to the input terminal, and the emitter of the transistor is connected to the ground , the collector of the transistor is respectively connected to the output terminal and the circuit voltage source; the bias circuit is connected in series between the base of the transistor and the reference voltage source; the first ESD protection circuit is connected to Between the collector of the transistor and the ground, it is used to provide electrostatic discharge protection for the transistor; it is characterized in that,

The first ESD protection circuit includes a first transistor, a first diode, a second diode and a third diode;

The base of the first transistor is set in an open circuit, the collector of the first transistor is connected to the circuit voltage source, and the emitter of the first transistor is connected to the anode of the first diode;

the cathode of the first diode is connected to ground;

The anode of the second diode is connected to ground, and the cathode of the second diode is connected to the collector of the first transistor;

The anode of the third diode is connected to ground, and the cathode of the third diode is connected to the collector of the first transistor.
The radio frequency power amplifier ESD protection circuit according to claim 1, is characterized in that, described first ESD protection circuit also comprises the 4th diode, and described 4th diode is connected in series with described first diode and ground, and the anode of the fourth diode is connected to the cathode of the first diode.
The radio frequency power amplifier ESD protection circuit according to claim 1 or 2, wherein the radio frequency power amplifier ESD protection circuit also includes a second ESD protection circuit, and the second ESD protection circuit is connected to the reference voltage source and ground, for providing electrostatic discharge protection for the bias circuit; the second ESD protection circuit includes a second transistor, a fifth diode, and a sixth diode;

The base of the second transistor is set in an open circuit, the emitter of the second transistor is connected to ground, and the collector of the second transistor is connected to the reference voltage source;

The anode of the fifth diode is connected to ground, and the cathode of the fifth diode is connected to the collector of the second transistor;

The anode of the sixth diode is connected to ground, and the cathode of the sixth diode is connected to the collector of the second transistor.
The radio frequency power amplifier ESD protection circuit according to claim 3, wherein the transistor, the first transistor and the second transistor are all GaAs-based HBT transistors.
The radio frequency power amplifier ESD protection circuit according to claim 4, wherein the transistor, the first transistor and the second transistor are all PNP transistors.
The radio frequency power amplifier ESD protection circuit according to claim 3, characterized in that, the radio frequency power amplifier ESD protection circuit also includes an input impedance matching circuit, and the input impedance matching circuit is connected in series with the input terminal and the bias Place the first capacitor between the circuits.
The radio frequency power amplifier ESD protection circuit according to claim 3, characterized in that, the radio frequency power amplifier ESD protection circuit also includes an output impedance matching circuit, and the output impedance matching circuit includes a collector connected in series with the transistor and the An inductance between the first ESD protection circuit and a second capacitor connected in series between the collector of the transistor and the output terminal.