GaNHemt radio frequency switch control circuit and control method

Abstract

The application discloses a GaNHemt radio frequency switch control circuit and a control method, which comprises ground capacitors C1, C2 and C3, pull-down resistors R2 and R3, a delay resistor R1, voltage division resistors R4, R5, R6, R7, R8 and R9, and six MOS transistors. The MOS transistors are used as switching devices, TTL control high negative voltage can be realized, the negative voltage can reach about -60V, a faster voltage control scheme can be provided for the current GaN device, the timing sequence of the traditional control, i.e. the time response problem, is solved, the GaN radio frequency switch is controlled through single logic, and logic space is saved; the hardware delay resistor is used to avoid the jitter problem caused by uncertain control timing, and the problem that the GaNHemt tube cannot be controlled due to gate leakage in application can be solved.

Description

Technical Field

[0001] This invention belongs to the field of communication systems and relates to a GaNHemt radio frequency switch control circuit and control method. Background Technology

[0002] In recent years, with the development of semiconductor materials science, GaN material has been discovered. GaN is a cutting-edge semiconductor material with enormous potential. GaN has a bandgap three times larger than Si, a breakdown field strength ten times higher, a saturated electron mobility three times greater, and thermal conductivity twice as high. These performance advantages make GaN more suitable for high-power, high-frequency power devices than other materials. However, due to the characteristics of GaN, its gate turn-on voltage is generally around -2.4V. Furthermore, the lower the gate voltage, the more completely the drain-source channel is turned off; conversely, the closer the gate voltage is to 0V, the more completely the drain-source channel is turned on. Therefore, practical applications of GaN RF switches generally require a TTL-controlled switching device with low negative voltage and 0V to achieve high isolation and insertion loss performance. Therefore, research on GaN Nemt RF switch control circuits is essential.

[0003] Existing GaN high-power RF switches generally use dual control signals with control levels of -40V and 0V, employing reciprocal levels to select the switching path. The current mainstream solution is optocoupler control. Optocoupler control primarily achieves non-interference between the control and controlled ends through the isolation provided by the optocoupler. Only one LED on the control end is needed to activate the transistor on the controlled end, thus achieving control. However, since current GaN high-power RF switches typically have dual control signals, two optocouplers are required for control. This leads to uncertainty in the timing of the two control signals, resulting in the switch not being fully closed or fully open during path switching, causing power jitter during switching. In addition, optocoupler chips have turn-on delays and rise times when turned on. Taking Vishay's TCMT11 series as an example, the typical turn-on time is about 3µs and the rise time is 3µs under 5V conditions. The rise time is equivalent to the slew rate of the operational amplifier. When the controlled voltage is -40V, the rise time will be about 20µs. Therefore, the entire control process is basically about 25µs. Considering the current requirements for the transmit and receive switching time in special communication fields, the control circuit time can no longer guarantee the communication performance of the entire device.

[0004] To address these issues, designers are now employing MOSFET circuits to improve the switching time of control circuits. MOSFETs have switching times in the nanosecond range, significantly increasing the overall switching time of the link. However, for high-power GaN MOSFET RF switches, especially when a high negative voltage V is applied in one path... A This will cut off the GaN transistor, but the other path will have a voltage close to V.A The voltage leakage of / 2 means that in a typical MOSFET circuit, when one path is under high negative voltage, the other path cannot clamp the potential to 0V, resulting in incomplete switching. This leads to low isolation and high insertion loss, which will not meet the requirements of some demanding applications. Furthermore, this solution does not address the timing issues of the two control signals.

[0005] Therefore, there is an urgent need to design a simple, fast GaNHemt RF switch control circuit with timing functions. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0007] This invention provides a GaNHemt RF switch control circuit, including grounding capacitors C1, C2, and C3, pull-down resistors R2 and R3, delay resistor R1, voltage divider resistors R4, R5, R6, R7, R8, and R9, and MOS transistors; the MOS transistors include: enhancement-mode PMOS transistors D1, D3, and D4, and enhancement-mode NMOS transistors D2, D5, and D6; wherein, the source of D1 is connected to the gate of D2 through R1; the drain of D1 is connected to the source of D3, R3 is located between the drain of D1 and the source of D3 and grounded, and the source of D1 is connected to the control terminal; The drain of D2 is connected to the source of D4. R2 is located between the drain of D2 and the source of D4 and is grounded. The source of D2 is grounded through C1 and is connected to a constant power supply. R4 is located between the drain of D3 and the gate of D5. R6 is located between the source and gate of D5. The gate of D3 is grounded. R5 is located between the drain of D4 and the gate of D6. R7 is located between the source and gate of D6. The gate of D4 is grounded. The source of D5 is grounded through R8 and C2. R8 is also connected to a negative voltage source. The source of D6 is grounded through R9 and C3. R9 is also connected to a negative voltage source.

[0008] Furthermore, it also includes a power supply module that generates a high negative voltage and a normal control voltage to supply the control circuit.

[0009] Furthermore, it also includes logic devices that generate control levels that are directly supplied to the control circuit.

[0010] Furthermore, the logic device generates a control level, which is then supplied to the control circuit via a level converter.

[0011] Furthermore, the control level and the constant power supply level have the same potential.

[0012] On the other hand, a GaNHemt RF switch control method is also provided. The control circuit controls a normal TTL level through a switching device to achieve rapid switching between high negative voltage and 0V, thereby controlling the GaNHemt RF switch. The drain-source channel of the MOS transistor is turned on as the switching device.

[0013] This invention provides a novel positive voltage controlled negative voltage circuit for GaN RF switches. Using a MOSFET as the switching device, it achieves TTL control of high negative voltages, reaching approximately -60V. This provides a faster voltage control solution for current GaN devices, overcoming the timing and response issues inherent in traditional control methods. Its advantages include saving logic space by controlling the GaN RF switch with a single logic; hardware delay resistors to avoid jitter caused by uncertain control timing; and the solution to the problem of gate leakage leading to uncontrollable GaN MOSFETs in applications.

[0014] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a circuit topology diagram proposed in this invention.

[0017] Figure 2 The circuit proposed in this invention was tested. Figure 1 .

[0018] Figure 3 The circuit proposed in this invention was tested. Figure 2 . Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0020] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not imply the presence or addition of one or more other elements or combinations thereof.

[0021] like Figure 1As shown, this invention provides a GaNHemt RF switch control circuit, including grounding capacitors C1, C2, and C3, pull-down resistors R2 and R3, delay resistor R1, voltage divider resistors R4, R5, R6, R7, R8, and R9, and MOSFETs; the MOSFETs include: enhancement-mode PMOS transistors D1, D3, and D4, and enhancement-mode NMOS transistors D2, D5, and D6; wherein, the source of D1 is connected to the gate of D2 through R1; the drain of D1 is connected to the source of D3, R3 is located between the drain of D1 and the source of D3 and grounded, and the source of D1 is connected to the control terminal. The drain of D2 is connected to the source of D4. R2 is located between the drain of D2 and the source of D4 and is grounded. The source of D2 is grounded through C1 and connected to a constant power supply. R4 is located between the drain of D3 and the gate of D5. R6 is located between the source and gate of D5. The gate of D3 is grounded. R5 is located between the drain of D4 and the gate of D6. R7 is located between the source and gate of D6. The gate of D4 is grounded. The source of D5 is grounded through R8 and C2. R8 is also connected to a negative voltage source. The source of D6 is grounded through R9 and C3. R9 is also connected to a negative voltage source.

[0022] In the embodiments provided by the present invention, the power module generates a high negative voltage and a normal control voltage to supply the control circuit.

[0023] In the embodiments provided by the present invention, the logic device generates a control level that is directly supplied to the control circuit.

[0024] In the embodiments provided by the present invention, the logic device generates a control level and supplies it to the control circuit via a level converter.

[0025] In the embodiments provided by the present invention, the control level and the constant power supply level have the same potential.

[0026] On the other hand, a GaNHemt RF switch control method is also provided. The control circuit controls a normal TTL level through a switching device to achieve rapid switching between high negative voltage and 0V, thereby controlling the GaNHemt RF switch. The drain-source channel of the MOS transistor is turned on as the switching device.

[0027] That is, the control circuit can use ordinary TTL level to control high negative voltage, and can pull the potential to 0V when there is leakage at the controlled end, thereby ensuring the full opening of the RF switch system. Timing control can be achieved without software timing control. In this invention, the constraint condition is to achieve the switching characteristics by conducting the drain-source channel of the MOS transistor within a specific range.

[0028] The specific control process consists of the following steps:

[0029] 1. The system supplies power supply voltage Vd to the power module LT8570 and control circuit. Vd is a constant power supply, typically 3.3V or 5V. The power module generates the control voltage Vs required for the GaN RF switch, typically around -40V to -50V.

[0030] 2. Logic devices are used to generate control level V_CON. It should be noted that the control level V_CON needs to be consistent with the potential of the constant power supply level Vd.

[0031] 3. When the control level is high, P transistor D2 is cut off. The drain of D2 is pulled down to low level through pull-down resistor R2. At this time, the source and gate of P transistor D4 are both low level, and D4 is cut off. The source and drain potentials of D6 are the same, and D6 is not conducting. At this time, Vs is sent to the gate of GaNHemt RF switch after being divided by R9. At this time, RF switch channel 2 is closed.

[0032] 4. Due to the device characteristics of GaNHemt, there will be a voltage leakage of close to Vs / 2 at the gate on the other side. Therefore, channel 1 does not reach the turn-on voltage. The ordinary resistor pull-down method cannot form a voltage divider structure with the internal resistance of GaN, and cannot pull the gate voltage to 0V.

[0033] 5. When channel 2 (referring to the left side of the control circuit, D2, D4, D6) is closed, the gate voltage of channel 1 (referring to the left side of the control circuit, D1, D3, D5) can be pulled to 0V. Specifically, when the control voltage is high, P-tube D1 is turned on, the drain of P-tube D3 is at a high level, and the gate is at a low level. D3 is turned on, the drain of D3 is at a high potential, and Vs is at a low potential. Through the voltage divider resistors R4, R6, and R8, the gate voltage of N-tube D5 is made greater than the turn-on voltage VGTH. At this time, the source-drain channel of D5 is opened, directly pulling the gate leakage voltage of GaNHemt in channel 1 to ground, ensuring that the voltage at this point reaches 0V, thereby turning on channel 1 and realizing the switching.

[0034] 6. Conversely, when the control level is low, channel 1 is closed and channel 2 is open.

[0035] 7. Due to the presence of the delay resistor R1, the response time of channel 1 is faster than that of channel 2. Because of the delay resistor R1, the switch always ensures that one channel is open before the other begins to operate, avoiding signal instability caused by switch bounce.

[0036] like Figure 2 As shown, when the control voltage changes from low to high, channel 1 switches from high negative voltage to 0V, and channel 2 switches from 0V to high negative voltage; the switching time is 8.4µs.

[0037] like Figure 3As shown, when the control voltage changes from high to low, channel 2 switches from high negative voltage to 0V, and channel 1 switches from 0V to high negative voltage; the switching time is 7.2us.

[0038] from Figure 2 and 3 As can be seen, the voltage rise rate is faster than the fall rate. This problem is mainly due to the slew rate of the MOSFET. Therefore, if dual signals are used as control signals, race conditions and hazards will occur. This solution can use the rising or falling edge of a single control voltage as a trigger signal to avoid the race conditions and hazards of dual-channel control.

[0039] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Other modifications can be easily implemented by those skilled in the art. Therefore, the present invention is not limited to the specific embodiments described above; the specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art, under the guidance of the present invention, can make many other modifications without departing from the spirit and scope of the claims, all of which are within the protection scope of the present invention.

Claims

1. A GaNHemt radio frequency switch control circuit, characterized in that, This includes grounding capacitors C1, C2, and C3; pull-down resistors R2 and R3; delay resistor R1; voltage divider resistors R4, R5, R6, R7, R8, and R9; and MOSFETs. The MOS transistors include: enhancement-mode PMOS transistors D1, D2, D3, and D4, and enhancement-mode NMOS transistors D5 and D6; wherein, The source of D1 is connected to the gate of D2 through R1; the drain of D1 is connected to the source of D3, R3 is located between the drain of D1 and the source of D3 and grounded, and the source of D1 is connected to the control terminal; the drain of D2 is connected to the source of D4, R2 is located between the drain of D2 and the source of D4 and grounded, the source of D2 is grounded through C1, and the source of D2 is connected to the constant power supply; R4 is located between the drain of D3 and the gate of D5, R6 is located between the source and gate of D5, and the gate of D3 is grounded; R5 is located between the drain of D4 and the gate of D6, and R7 is... Between the source and gate of D6, the gate of D4 is grounded; the source of D5 is grounded through R8 and C2, and the connection node of R8 and C2 is connected to the negative voltage source; the source of D6 is grounded through R9 and C3, and the connection node of R9 and C3 is connected to the negative voltage source; the gate of D1, the drain of D5, and the gate of D6 are all grounded; the control circuit uses ordinary TTL level to control the high negative voltage, and pulls the potential to 0V when there is leakage at the control terminal; the control level V_CON received by the control terminal is consistent with the potential of the normally supplied power supply Vd level; The output node of the control circuit is connected to the gate inside the GaNHemt device, and the output node of the control circuit is connected to the source of D5 and the source of D6.

2. The GaNHemt RF switch control circuit as described in claim 1, characterized in that, It also includes a power module that generates a high negative voltage and a normal control voltage to supply the control circuit.

3. The GaNHemt RF switch control circuit as described in claim 1, characterized in that, It also includes logic devices, which generate control levels that are directly supplied to the control circuit.

4. The GaNHemt RF switch control circuit as described in claim 3, characterized in that, The logic device generates a control level, which is then supplied to the control circuit via a level converter.

5. A GaNHemt radio frequency switch control method, characterized in that, The GaNHemt RF switch control circuit as described in any one of claims 1-4 is used, wherein the control circuit controls a normal TTL level through a switching device to achieve rapid switching between high negative voltage and 0V, thereby controlling the GaNHemt RF switch.

6. The GaNHemt RF switch control method as described in claim 5, characterized in that, The drain-source channel of the MOS transistor is turned on as a switching device.

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