N-channel depletion type GaN HEMT device with grid positive voltage bias

Abstract

The utility model discloses an N-channel depletion type GaN HEMT device with a bias grid positive voltage, which comprises an N-channel depletion type GaN HEMT device and a source resistor Rs, the source resistor Rs is connected to the source of the N-channel depletion type GaN HEMT device, the other end of the source resistor Rs is grounded, the grid voltage VG is in positive voltage bias, the VG is less than or equal to VTH + Vs, and the channel of the N-channel depletion type GaN HEMT device is in a pinch-off state. According to the N-channel depletion type GaN HEMT device, no extra power supply chip needs to be added to provide negative voltage in the application of the N-channel depletion type GaN HEMT device, no extra sequential circuit needs to be added to ensure the power-on and power-off sequence, and the device is prevented from being burnt down.

Description

Technical Field

[0001] The utility model relates to the field of microwave power amplification integrated circuits, in particular to an N-channel depletion-type GaN HEMT device with a positive gate voltage bias. Background Art

[0002] N-channel field effect transistors (FETs) can be divided into enhancement mode (E-mode, normally off) and depletion mode (D-mode, normally on) according to the conduction type of the channel. TH Greater than 0, that is, the gate-source voltage V GS When it is 0V, the channel is not conducting and a voltage greater than V TH Forward V GS A bias voltage is required to form a channel. For depletion mode devices, V TH Less than 0, when V GS When the voltage is 0V, the drain-source resistance is close to 0Ω, and the channel is already conducting. Therefore, when using a depletion-mode device, a negative gate bias voltage needs to be applied before applying the drain-source voltage to pinch off the channel and avoid device failure due to overcurrent breakdown.

[0003] Taking HEMT devices based on the third-generation semiconductor gallium nitride (GaN) as an example, GaN HEMTs are widely used in power electronics, radio frequency microwaves, and other fields. The high-mobility two-dimensional electron gas (2DEG) channel formed by the AlGaN / GaN heterojunction in GaN HEMTs has a natural conduction characteristic, exhibiting a normally-on behavior. However, biasing considerations are necessary when using these devices.

[0004] In power device applications, p-GaN technology is often used to raise the conduction band of the entire heterojunction, thereby depleting the 2DEG in the heterojunction's conductive channel and transitioning the device from depletion mode to enhancement mode. Alternatively, a cascode structure can be used, where a low-voltage enhancement-mode Si MOSFET and a depletion-mode GaN HEMT are packaged in series to form a normally-off device.

[0005] In the field of RF microwave power amplification applications, in order to ensure the RF characteristics of GaN HEMT devices, depletion-mode devices are still mostly used. Therefore, the gate needs to use a negative bias voltage. In system applications, additional power supply chips need to be added to provide negative voltage. At the same time, additional timing circuits need to be added to ensure the power-on and power-off sequence to prevent chip burnout.

[0006] Traditional N-channel depletion mode devices such as Figure 1 As shown. The source is usually grounded GND, and the reference voltage is 0V, that is, VS = 0V. When drawing the layout of this type of single-tube device, the source is usually directly connected to the back hole (Backsie Via) through metal. Therefore, in the circuit system, a sufficiently negative gate voltage V needs to be applied first when powering on.G , making V GS ≤V TH , to pinch off the channel, where V GS =V G -VS. Utility Model Content

[0007] In view of the shortcomings of the existing technology, the present invention proposes an N-channel depletion-type device structure whose gate can be biased with a positive voltage. Such devices include but are not limited to junction field-effect transistors and insulated gate field-effect transistors.

[0008] The technical solution of the utility model is:

[0009] The utility model proposes an N-channel depletion-type GaN HEMT device structure, including a drain positive power supply terminal V DD , Gate positive power supply terminal V GG , N-channel depletion-mode GaN HEMT device and source resistor Rs, the source of the N-channel depletion-mode GaN HEMT device is connected to the source resistor Rs, the other end of the source resistor Rs is grounded, and the gate is set to a positive voltage bias so that the gate bias voltage V G Greater than or equal to 0, drain-source current I DS The parameter selection of the source resistor Rs enables the channel pinch-off of the N-channel depletion-mode GaN HEMT device.

[0010] The gate positive voltage bias can be applied by the gate positive power supply terminal V GG Generated, can also be drained through the positive power supply terminal V DD The positive power supply terminal V DD Provides a drain-source current of I for the N-channel depletion-mode GaN HEMT device DS .

[0011] The drain-source current of an N-channel depletion-mode GaN HEMT device is I DS , then the voltage drop across the source resistor Rs is Rs×I DS , that is, the source voltage of the N-channel depletion-mode GaN HEMT device is Vs=Rs×I DS . The gate bias voltage V G ≤V TH +Vs, the conditions for pinching off the channel are met. According to the drain-source current I DS Working range, determine the value of source resistor Rs, let |V TH |≤Vs=Rs×I DS , which can satisfy the gate voltage V G ≥0V.

[0012] The above structure is preferably implemented through on-chip integration, but can also be implemented through discrete devices. The source resistor Rs can be an independent resistor, or it can be implemented by connecting multiple resistors of the same or different resistance values ​​in series, parallel, or series-parallel. The source resistor Rs can also be any component that primarily exhibits resistance characteristics.

[0013] Beneficial effects of the utility model:

[0014] Connecting a source resistor Rs between the source and ground of an N-channel depletion-mode GaN HEMT device can satisfy the positive gate bias voltage V G ≤V TH When +Vs is applied, the conditions for pinching off the channel of an N-channel depletion-mode GaN HEMT device are met. In RF microwave power amplification applications, depletion-mode devices are still often used to ensure the RF characteristics of GaN HEMT devices, so the gate needs to adopt a negative bias voltage. This utility model eliminates the need for additional power supply chips to provide negative voltage in system applications, requiring only two or a single positive power supply. It also eliminates the need for additional timing circuits to ensure power-up and power-down sequencing, preventing chip device burnout. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of a traditional N-channel depletion-mode device;

[0016] Figure 2 This is the principle diagram of the N-channel depletion-mode GaN HEMT device of the utility model;

[0017] Figure 3 This is one of the variations of the schematic diagram of the N-channel depletion-mode GaN HEMT device of the present invention;

[0018] Figure 4 This is the second variation of the schematic diagram of the N-channel depletion-mode GaN HEMT device of the present invention;

[0019] Figure 5 This is the third variation of the schematic diagram of the N-channel depletion-mode GaN HEMT device of the present invention;

[0020] Figure 6 This is the fourth variation of the schematic diagram of the N-channel depletion-mode GaN HEMT device of the present invention. DETAILED DESCRIPTION

[0021] The following is further described with reference to the accompanying drawings:

[0022] like Figure 2 As shown in the schematic diagram of the N-channel depletion-type GaN HEMT device of the utility model, the drain positive power supply terminal V DD , gate positive power supply terminal V GG , the drain-source current is IDS , then the voltage drop across the source resistor Rs is Rs×I DS , that is, the source voltage of the device Vs=Rs×I DS . The gate bias voltage V G ≤V TH +Vs, the conditions for pinching off the channel can be met. By properly designing the device current I DS and Rs, let |V TH |≤Vs=Rs×I DS , which can satisfy the gate voltage V G ≥0V.

[0023] The above structure can be implemented through on-chip integration or discrete components. The source resistor Rs can be a single resistor or multiple resistors of equal or different values ​​connected in series, parallel, or in series-parallel configurations. The source resistor Rs can be any component that primarily exhibits resistance characteristics.

[0024] like Figure 3 As shown in a variation of the schematic diagram of the N-channel depletion-mode GaN HEMT device of this invention, multiple resistors Rs1, Rs2, ..., and Rsn are connected in parallel to form the source resistor Rs. Connecting multiple resistors in parallel increases the area occupied by the resistors, reducing local current density and heat generation. It also minimizes resistance errors caused by process tolerances and reduces the parasitic inductance introduced by the source resistors. It also forms multiple heat dissipation paths, improving on-chip heat distribution.

[0025] like Figure 4 As shown in the second variation of the schematic diagram of the N-channel depletion-mode GaN HEMT device in this invention, a source resistor Rs and a source capacitor Cs are connected in parallel. The capacitive reactance of the capacitor decreases with increasing operating frequency. By connecting the capacitor in parallel with the source resistor, high-frequency response is improved, AC characteristics are enhanced, and the DC operating point is stabilized without affecting DC characteristics.

[0026] like Figure 5 As shown in the third variation of the schematic diagram of the N-channel depletion-mode GaN HEMT device of this utility model, resistors Rs1 and Rs2 are connected in series, Rs2 is connected in parallel with capacitor Cs, and the entire resistor-capacitor network forms the source resistor Rs. This can be compensated in the high frequency band to increase the bandwidth. And compared to Figure 4 The circuit structure shown is Figure 5 The circuit structure improves high-frequency performance and has more flexibility in component values.

[0027] like Figure 6As shown in the fourth variation of the schematic diagram of the N-channel depletion-mode GaN HEMT device of the present invention, the source resistor Rs is properly designed so that the gate does not need an additional power supply. Instead, a large gate resistor RG is used to directly connect the gate to ground. Since the gate current can be ignored, the gate potential VG = 0V.

[0028] In summary, considering the device's frequency characteristics, efficiency, linearity, power, gain and other technical indicators, variations of the above structure include but are not limited to connecting a capacitor Cs or other components in parallel with the resistor Rs.

Claims

1. An N-channel depletion-mode GaN HEMT device with a positive gate bias, characterized by: Including the gate positive power supply terminal (V GG ), drain positive power supply terminal (V DD ), N-channel depletion-mode GaN HEMT device and source resistance (Rs); Gate positive power supply terminal (V GG ) provides a positive bias voltage for the gate of the N-channel depletion-mode GaN HEMT device, or the gate voltage of the N-channel depletion-mode GaN HEMT device (V G ) from the drain positive power supply terminal (V DD ) is provided by resistor voltage division or voltage-stabilized power supply chip; Drain positive power supply terminal (V DD ) provides drain-source current (I DS ); The source of the N-channel depletion-mode GaN HEMT device is connected to the source resistor (Rs), and the other end of the source resistor (Rs) is grounded. The gate voltage (V G ) is set to a positive bias, and the channel of the N-channel depletion-mode GaN HEMT device is in a pinch-off state.

2. The N-channel depletion-mode GaN HEMT device with a positive gate bias according to claim 1, characterized in that: The gate voltage (V G )scope: In TH +Vs≥V G ≥0; in: V TH： N-channel depletion-mode GaN HEMT device threshold voltage, V TH <0; Vs: N-channel depletion-mode GaN HEMT device source voltage, Vs = Rs × I DS， I DS is the drain-source current of the N-channel depletion-mode GaN HEMT device.

3. The N-channel depletion-mode GaN HEMT device with a positive gate bias according to claim 2, characterized in that: The source resistor (R S ).

4. The N-channel depletion-mode GaN HEMT device with a positive gate bias according to claim 3, characterized in that: The RC network is composed of multiple resistors connected in parallel to form a source resistor (R S ).

5. The N-channel depletion-mode GaN HEMT device with a positive gate bias according to claim 3, characterized in that: The RC network is a source resistor (R S ).

6. The N-channel depletion-mode GaN HEMT device with a positive gate bias according to claim 3, characterized in that: The RC network is a resistor in series with a RC network in parallel to form a source resistor (R S ).

7. The N-channel depletion-mode GaN HEMT device with a positive gate bias according to claim 2, characterized in that: The gate resistance (R G ), gate resistance (R G ) is grounded, and the gate voltage V G =0V.

Images