Drive circuit and radio frequency switch circuit

Abstract

A driving circuit and a radio frequency switch circuit, the driving circuit is adapted to drive the radio frequency switch, the driving circuit comprises: a step-down level conversion circuit module. The source is adapted to input a first power voltage, or the drain is adapted to input the first power voltage. The input end of the step-down level conversion circuit module is connected to the gate of the radio frequency switch, and the output end of the step-down level conversion circuit module is connected to the substrate of the radio frequency switch. The step-down level conversion circuit module is adapted to receive a control signal at the input end, provide a second on voltage to the output end when the control signal is a first on voltage, and provide a second off voltage to the output end when the control signal is a first off voltage. Wherein, the first on voltage is greater than the second on voltage, the first on voltage is greater than the first power voltage, the second on voltage is not less than the first power voltage, the first on voltage is greater than the first off voltage, and the second off voltage is not greater than the first power voltage and not less than the first off voltage.

Description

Technical Field

[0001] This invention relates to the field of radio frequency switches, and more particularly to a driving circuit and a radio frequency switch circuit. Background Technology

[0002] The body region driving method of SOI (Silicon-On-Insulator) switching devices is crucial to breakdown voltage and process FOM (Figure of Merit). A reasonable body region driving method not only helps optimize RF switch power capability and performance such as harmonics, insertion loss, and isolation, but also simplifies circuit design and saves chip area.

[0003] Figure 1 A driving circuit for an existing radio frequency switch is provided, comprising: a gate bias resistor Rg, a substrate bias resistor Rb, a source bias resistor Rs, a source path resistor Rds, and an inverter INV, for driving the radio frequency switch Msw.

[0004] The first terminal of the gate bias resistor Rg is adapted to receive the control signal CT0, and the second terminal of the gate bias resistor Rg is connected to the gate of the RF switch MSw. The input terminal of the inverter INV is connected to the first terminal of the gate bias resistor Rg, the output terminal of the inverter INV is connected to the first terminal of the source bias resistor Rs, and the power supply terminal of the inverter INV is adapted to receive the first power supply voltage Vdd. The second terminal of the source bias resistor Rs is connected to the source of the RF switch MSw and the first terminal of the source path resistor Rds. The second terminal of the source path resistor Rds is connected to the drain of the RF switch MSw. The first terminal of the substrate bias resistor Rb is connected to the substrate of the RF switch MSw, and the second terminal of the substrate bias resistor Rb is adapted to receive the ground voltage.

[0005] During operation, the logic module outputs a high-level control signal CT0 to turn on the RF switch Msw. The high-level control signal CT0 is equal to the first power supply voltage Vdd. The logic module outputs a low-level control signal CT0 to turn off the RF switch Msw. The voltage of the low-level control signal CT0 is equal to the ground voltage.

[0006] from Figure 1 As shown in the circuit structure, its source, drain, and gate are dynamically biased, while the substrate is fixed at a bias ground. It utilizes a relative voltage difference to achieve positive voltage turn-on and negative voltage turn-off control, requiring only a positive voltage drive. The circuit is relatively simple and has relatively low power consumption. Furthermore, the positive voltage turn-on and negative voltage turn-off driving bias method can improve RF performance such as insertion loss, isolation, power handling capability, and linearity.

[0007] Figure 2A radio frequency (RF) switch circuit is formed using the above-described structure. The RF switch circuit includes: RF switch unit 11, RF switch unit 12, RF switch unit 13, RF switch unit 14, a first RF input / output port RF1, a second RF input / output port RF2, and a third RF input / output port RFC.

[0008] Each RF switch unit includes, in addition to the RF switch and its driving circuit, two DC blocking capacitors. Specifically, RF switch unit 11 includes DC blocking capacitors Cbb1 and Cbs1; RF switch unit 12 includes DC blocking capacitors Cbb2 and Cbs2; RF switch unit 13 includes DC blocking capacitors Cbb3 and Cbs3; and RF switch unit 14 includes DC blocking capacitors Cbb4 and Cbs4.

[0009] The first RF input / output port RF1 is connected to the RF switch unit 11 via a DC blocking capacitor Cbs1, and to the RF switch unit 13 via a DC blocking capacitor Cbb3. The second RF input / output port RF2 is connected to the RF switch unit 12 via a DC blocking capacitor Cbs2, and to the RF switch unit 14 via a DC blocking capacitor Cbb4. The third RF input / output port RFC is connected to the RF switch unit 11 via a DC blocking capacitor Cbb1, and to the RF switch unit 12 via a DC blocking capacitor Cbb2.

[0010] Existing technology incorporates two DC blocking capacitors in each RF switching unit to maintain dynamic independence of the source-drain bias of each unit and prevent control signals from interfering with each other through the source or drain connection. For example, when control signal CT11 is input to RF switching unit 11, it can affect RF switching unit 12 through the source bias resistor and source path resistor, thereby interfering with the driving of RF switching unit 12 by control signal CT12. The DC blocking capacitors Cbb1 and Cbb2 can prevent this problem from occurring.

[0011] However, as Figure 3 As shown, the more DC blocking capacitors are set, the greater the insertion loss is introduced, which seriously degrades the insertion loss performance of the RF switch. Summary of the Invention

[0012] The problem solved by this invention is that the insertion loss introduced by the DC blocking capacitor setting in the existing RF switch circuit is too large.

[0013] To address the aforementioned problems, this invention provides a driving circuit suitable for driving a radio frequency (RF) switch. The RF switch includes a source, a drain, a gate, and a substrate. The driving circuit includes a buck level conversion circuit module. The source is adapted to receive a first power supply voltage, or the drain is adapted to receive the first power supply voltage. The input terminal of the buck level conversion circuit module is connected to the gate of the RF switch, and the output terminal of the buck level conversion circuit module is connected to the substrate of the RF switch. The buck level conversion circuit module is adapted to receive a control signal at its input terminal, provide a second turn-on voltage to its output terminal when the control signal is a first turn-on voltage, and provide a second turn-off voltage to its output terminal when the control signal is a first turn-off voltage. Wherein, the first turn-on voltage is greater than the second turn-on voltage, the first turn-on voltage is greater than the first power supply voltage, the second turn-on voltage is not less than the first power supply voltage, the first turn-on voltage is greater than the first turn-off voltage, and the second turn-off voltage is neither greater than the first power supply voltage nor less than the first turn-off voltage.

[0014] The present invention also provides a radio frequency (RF) switch circuit, comprising: an RF switch unit. The RF switch unit includes: an RF switch and the aforementioned driving circuit.

[0015] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0016] The buck level conversion circuit module of this invention introduces a control signal from the substrate of the RF switch, and through the control of the buck level conversion circuit module, realizes that the gate voltage of the RF switch dynamically follows the substrate voltage change in phase, thereby driving the RF switch. Since this invention no longer uses the source-drain and gate dynamic biasing used in the prior art, the number of DC blocking capacitors inserted on the source or drain is reduced, which simplifies the circuit, saves the area of ​​DC blocking capacitors, and reduces insertion loss. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a driving circuit for an existing radio frequency switch;

[0018] Figure 2 This is a schematic diagram of the structure of an existing radio frequency switch circuit;

[0019] Figure 3 The graph shows the relationship between the existing DC blocking capacitor and the insertion loss.

[0020] Figure 4 This is a schematic diagram of the driving circuit structure of the radio frequency switch in this embodiment;

[0021] Figure 5 This is a schematic diagram of the radio frequency switch circuit in this embodiment;

[0022] Figure 6 This is a diagram showing the relationship between the DC blocking capacitance and the insertion loss in this embodiment. Detailed Implementation

[0023] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Please refer to... Figure 4 This application provides a driving circuit adapted to drive a radio frequency switch M, which includes a gate, a substrate, a source, and a drain.

[0024] The driving circuit includes a buck level conversion circuit module 20. The input terminal of the buck level conversion circuit module 20 is connected to the gate of the RF switch M, and the output terminal of the buck level conversion circuit module 20 is connected to the substrate of the RF switch M. The source terminal receives a first power supply voltage Vdd, or the drain terminal receives the first power supply voltage Vdd.

[0025] The step-down level conversion circuit module 20 can receive a control signal CT at its input terminal, and provide a second turn-on voltage to its output terminal when the control signal CT is a first turn-on voltage; and provide a second turn-off voltage to its output terminal when the control signal CT is a first turn-off voltage.

[0026] The first turn-on voltage is greater than the second turn-on voltage. The first turn-on voltage is greater than the first power supply voltage Vdd, and the second turn-on voltage is not less than the first power supply voltage Vdd. The first turn-on voltage is greater than the first turn-off voltage, and the second turn-off voltage is neither greater than the first power supply voltage Vdd nor less than the first turn-off voltage.

[0027] The voltage value of the first turn-on voltage can be the voltage value of the first power supply voltage Vdd. vdd The first turn-on voltage is an integer multiple of the first power supply voltage Vdd, such as twice the first power supply voltage Vdd. Hereafter, the first turn-on voltage is assumed to be 2*V. vdd For example, the second turn-on voltage can be equal to the first power supply voltage Vdd. The first power supply voltage Vdd is the on-chip power supply voltage of the RF switch M. The first turn-off voltage can be ground.

[0028] When the control signal CT is 2*V vdd At that time, the output terminal of the step-down level conversion circuit module 20 outputs V. vdd Therefore, the gate of RF switch M is connected to 2*V. vdd The substrate of the RF switch M is connected to V. vdd RF switch M is turned on.

[0029] When the control signal CT is ground voltage, the output of the step-down level conversion circuit module 20 has a second turn-off voltage that is greater than or equal to ground voltage and less than or equal to the first power supply voltage Vdd, such as a voltage between ground voltage and Vdd. vdd The voltage between. At this time, the source or drain of the RF switch M is connected to V. vdd The gate voltage is connected to ground, and the substrate voltage is connected between ground and V. vdd The voltage between the source and drain is less than the voltage of the source or drain. Therefore, the gate voltage of the RF switch M is less than the voltage of the source or drain, and the substrate voltage is also less than the voltage of the source or drain, causing the RF switch M to turn off.

[0030] When the second turn-on voltage is greater than the first power supply voltage Vdd, the substrate voltage is greater than the source-drain voltage, and the insertion loss is further reduced by utilizing the substrate bias effect.

[0031] Therefore, this embodiment employs a substrate-to-gate dynamic control signal and, through adjustment by a step-down level conversion circuit module, achieves dynamic in-phase following of the gate voltage change by the substrate voltage, thereby driving the RF switch. Since this embodiment no longer uses... Figure 1 The source, drain, and gate are dynamically biased as shown, thus reducing the number of DC blocking capacitors inserted on the source or drain. This simplifies the circuit, saves the area of ​​the DC blocking capacitors, and reduces insertion loss.

[0032] Furthermore, the control signal CT is 2*V vdd The voltage is either ground voltage, i.e., a positive voltage, to drive the RF switch. The first power supply voltage Vdd can be provided by the analog unit 30. The analog unit 30 generates a second power supply voltage based on the input power supply AVdd, and the voltage value of the second power supply voltage is n*V. vdd The voltage value n is an integer multiple of the first power supply voltage Vdd, where n is a positive integer. Specifically, analog unit 30 outputs a second power supply voltage equal to the first power supply voltage Vdd to its source or drain (n=1), and outputs a second power supply voltage that is a multiple of the first power supply voltage Vdd to logic unit 40 (n≥2). The control signal CT can be provided by logic unit 40 operating in the low-voltage domain, which generates the control signal CT based on the second power supply voltage. Compared to the negative voltage driving method, the positive voltage driving method does not require additional complex modules, simplifying the circuit and saving chip area.

[0033] The step-down level conversion circuit module 20 includes a first diode D1 and multiple second diodes connected in series.

[0034] The series of multiple second diodes means that the cathode of the first second diode D21 is connected to the anode of the second second diode, and so on, and the cathode of the penultimate second diode is connected to the anode of the last second diode D2n.

[0035] The cathode of the first diode D1 is connected to the anode of the first second diode D21 and the input terminal of the buck level conversion circuit module. The anode of the first diode D1 is connected to the cathode of the last second diode D2n and the output terminal of the buck level conversion circuit module.

[0036] The driving circuit may further include: a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4.

[0037] The input terminal of the buck level conversion circuit module 20 is connected to the gate of the RF switch M through the second resistor R2. Specifically, the first end of the second resistor R2 is connected to the gate of the RF switch M, and the second end of the second resistor R2 is connected to the input terminal of the buck level conversion circuit module 20, and receives the control signal CT.

[0038] The output terminal of the buck level conversion circuit module 20 is connected to the substrate of the RF switch M through the first resistor R1. Specifically, the first end of the first resistor R1 is connected to the substrate of the RF switch M, and the second end of the first resistor R1 is connected to the output terminal of the buck level conversion circuit module 20.

[0039] In this embodiment, a control signal CT is introduced from the gate of the RF switch M, and a loop is formed between the gate and the substrate of the RF switch M through the step-down level conversion circuit module 20. Therefore, inserting the first resistor R1 and the second resistor R2 into the loop can effectively prevent the transmission of RF signals in the loop.

[0040] The first terminal of the third resistor R3 is input with the first power supply voltage Vdd, the second terminal of the third resistor R3 is connected to the source of the RF switch M, the first terminal of the fourth resistor R4 is connected to the source of the RF switch M, and the drain of the fourth resistor R4 is connected to the drain of the RF switch M, that is, the source and drain are used to fix the driving signal.

[0041] This embodiment also provides a radio frequency (RF) switch circuit, including: an RF switch unit. The RF switch unit includes: an RF switch and the aforementioned driving circuit. The number of the RF switch units can be at least two; the following description uses four RF switch units as an example.

[0042] like Figure 5 As shown, the radio frequency switch circuit includes: a first radio frequency switch unit 21, a second radio frequency switch unit 22, a third radio frequency switch unit 23, a fourth radio frequency switch unit 24, a first DC blocking capacitor C1, a second DC blocking capacitor C2, a third DC blocking capacitor C3, a first radio frequency signal input / output port RF1, a second radio frequency signal input / output port RF2, and a third radio frequency signal input / output port RFC.

[0043] The first RF switch unit 21, the second RF switch unit 22, the third RF switch unit 23, and the RF switch unit 24 all adopt... Figure 4 The structure shown employs a substrate and gate driving method, resulting in minimal impact of control signals between RF switching units. For example, if control signal CT21 enters through the gate of the RF switch in the first RF switching unit 21, it has minimal impact on the first RF switching unit 22 connected to it. Therefore, there is no need to provide DC blocking capacitors on each source and drain; that is, the source or drain of an RF switch can be directly connected to the source or drain of other RF switches without the need for DC blocking capacitors.

[0044] In this configuration, the RF switching units can share the DC blocking capacitor connected to the RF signal input / output port, reducing the power consumption of the drive circuit. Specifically, the first end of the DC blocking capacitor is connected to the RF signal input / output port, and the second end of the DC blocking capacitor is connected to at least two RF switching units. In the RF switching units connected to the second end of the DC blocking capacitor, the source or drain of the RF switch is connected to the second end of the DC blocking capacitor.

[0045] exist Figure 5 In this configuration, the first end of the first DC blocking capacitor C1 is connected to the first radio frequency signal input / output port RF1, and the second end of the first DC blocking capacitor C1 is connected to the first radio frequency switch unit 21 and the third radio frequency switch unit 23. Both the first radio frequency switch unit 21 and the third radio frequency switch unit 23 are connected to the first radio frequency signal input / output port RF1 through the first DC blocking capacitor C1.

[0046] The first end of the second DC blocking capacitor C2 is connected to the second radio frequency signal input / output port RF2, and the second end of the second DC blocking capacitor C2 is connected to the second radio frequency switch unit 22 and the fourth radio frequency switch unit 24. Both the second radio frequency switch unit 22 and the fourth radio frequency switch unit 24 are connected to the second radio frequency signal input / output port RF2 through the second DC blocking capacitor C2.

[0047] The first end of the third DC blocking capacitor C3 is connected to the third radio frequency signal input / output port RFC, and the second end of the third DC blocking capacitor C3 is connected to the first radio frequency switch unit 21 and the second radio frequency switch unit 22. Both the first radio frequency switch unit 21 and the second radio frequency switch unit 22 are connected to the third radio frequency signal input / output port RFC through the third DC blocking capacitor C3.

[0048] In addition, the RF switch circuit may also include a fourth DC blocking capacitor C4 and a fifth DC blocking capacitor C5. The source or drain of the RF switch in the third RF switch unit 23 is grounded through the fourth DC blocking capacitor C4, and the source or drain of the RF switch in the fourth RF switch unit 24 is grounded through the fifth DC blocking capacitor C5.

[0049] Tested under the same parameters Figure 2 and Figure 5 The DC blocking capacitance and insertion loss of the RF switch circuit shown can be obtained. Figure 6 The relationship curve shown. Figure 6 Solid arcs represent this embodiment, while dashed arcs represent prior art. From Figure 6 It can be seen that this embodiment reduces insertion loss compared to the prior art.

[0050] As verified by the inventors of this application, since the source and drain of the RF switch use the same fixed driving voltage, the DC blocking capacitor of the RF switch connected to the RF input and output ports can be shared, which can improve insertion loss performance or save DC blocking capacitor area to reduce cost, resulting in an overall capacitor saving of 37.5%.

[0051] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A driving circuit adapted to drive a radio frequency switch, the radio frequency switch comprising: The source, drain, gate, and substrate are characterized in that the driving circuit includes: a buck level conversion circuit module; The source is adapted to receive the first power supply voltage, or the drain is adapted to receive the first power supply voltage; The input terminal of the buck level conversion circuit module is connected to the gate of the RF switch, and the output terminal of the buck level conversion circuit module is connected to the substrate of the RF switch. The buck level conversion circuit module is adapted to receive a control signal at its input terminal, provide a second turn-on voltage to its output terminal when the control signal is a first turn-on voltage, and have a second turn-off voltage to its output terminal when the control signal is a first turn-off voltage. Wherein, the first turn-on voltage is greater than the second turn-on voltage, the first turn-on voltage is greater than the first power supply voltage, the second turn-on voltage is not less than the first power supply voltage, the first turn-on voltage is greater than the first turn-off voltage, and the second turn-off voltage is neither greater than the first power supply voltage nor less than the first turn-off voltage.

2. The driving circuit as described in claim 1, characterized in that, The first turn-on voltage is an integer multiple of the first power supply voltage, and the second turn-on voltage is equal to the first power supply voltage.

3. The driving circuit as described in claim 1, characterized in that, The step-down level conversion circuit module includes: a first diode and multiple second diodes connected in series; The cathode of the first diode is connected to the anode of the first second diode and the input terminal of the buck level conversion circuit module; The anode of the first diode is connected to the cathode of the last second diode and the output of the buck level conversion circuit module.

4. The driving circuit as described in claim 1, characterized in that, Also includes: First resistor; The output of the buck level conversion circuit module is connected to the substrate of the RF switch through the first resistor.

5. The driving circuit as described in claim 1, characterized in that, Also includes: Second resistor; The input terminal of the buck level conversion circuit module is connected to the gate of the RF switch through the second resistor.

6. The driving circuit as described in claim 1, characterized in that, Also includes: Third resistor; The source receives the first power supply voltage through the third resistor, or the drain receives the first power supply voltage through the third resistor.

7. A radio frequency switching circuit, characterized in that, include: RF switch unit; The radio frequency switch unit includes: a radio frequency switch and a driving circuit as described in any one of claims 1 to 6.

8. The radio frequency switching circuit as described in claim 7, characterized in that, The number of radio frequency switch units is at least two, and the radio frequency switch circuit further includes: a DC blocking capacitor and a radio frequency signal input / output port. The first end of the DC blocking capacitor is connected to the radio frequency signal input / output port, and the second end of the DC blocking capacitor is connected to at least two radio frequency switch units.

9. The radio frequency switching circuit as described in claim 8, characterized in that, In the radio frequency switch unit connected to the second terminal of the DC blocking capacitor, the source or drain of the radio frequency switch is connected to the second terminal of the DC blocking capacitor.

10. The radio frequency switching circuit as described in claim 7, characterized in that, Also includes: Analog units and logic units; The analog unit is adapted to generate a second power supply voltage based on the input power supply, wherein the voltage value of the second power supply voltage is an integer multiple of the voltage value of the first power supply voltage. The logic unit is adapted to generate the control signal according to the second power supply voltage.

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