Differential radio frequency switch circuit and chip

Abstract

The utility model discloses a differential radio frequency switch circuit and a chip. The differential radio frequency switch circuit comprises a first switch unit, a second switch unit and a signal compensation module. And the first switch unit and the second switch unit respectively control the on-off between the differential signal input end and the corresponding differential signal output end based on the control signal. The signal compensation module is connected with the differential signal input end and the differential signal output end, and is used for generating a first compensation signal to compensate a first leakage signal generated by the first switch unit when the first switch unit is turned off; and generating a second compensation signal to compensate a second leakage signal generated by the second switch unit when the second switch unit is turned off. According to the differential radio frequency switch circuit and the chip, the isolation degree can be greatly improved in a broadband range, and the insertion loss of the switch is basically not influenced. In addition, few devices are added, the circuit is simple, the design is flexible, the implementation is easy, the circuit area is basically not increased, and the cost is low.

Description

Technical Field

[0001] The utility model belongs to the technical field of radio frequency switches, and in particular relates to a differential radio frequency switch circuit and a chip. Background Art

[0002] RF switches are widely used in communication systems. They can be used to switch RF front-end channels, switch between different frequency bands, and are also commonly used to switch signal paths within RF systems.

[0003] The main indicators of RF switches include: insertion loss when the switch is on, isolation when the switch is off, linearity, reliability, etc., among which insertion loss and isolation are the most important indicators.

[0004] Traditional solutions to improve the isolation of RF switches include: (1) increasing the number of switches, which increases isolation while increasing insertion loss proportionally; (2) adding switches connected in parallel to the ground to form a series-parallel structure, which also has the problem of increased isolation and increased insertion loss; (3) using a method to neutralize the resonance of inductance and parasitic capacitance to improve isolation, but this solution can only achieve good results within a narrowband frequency range, and the inductance area is large, which greatly increases the area of ​​the switch circuit.

[0005] Comparative document CN113300694B discloses an ultra-wideband, low-loss, high-isolation fully differential structure RF switch. The improvement of the isolation of this RF switch is limited, and the loss will also worsen while the isolation is increased.

[0006] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art. Utility Model Content

[0007] The purpose of the present utility model is to provide a differential radio frequency switch circuit and chip, which can greatly improve the isolation of the differential radio frequency switch while having a lower switch insertion loss.

[0008] In order to achieve the above-mentioned purpose, a specific embodiment of the present invention provides a differential RF switching circuit, including a first switch unit, a second switch unit and a signal compensation module, wherein the first end of the first switch unit and the first end of the second switch unit are connected to the differential signal input end, the second end of the first switch unit and the second end of the second switch unit are connected to the differential signal output end, the first switch unit and the second switch unit are used to control the on and off between the differential signal input end and the corresponding differential signal output end based on a control signal, the signal compensation module is connected to the differential signal input end and the differential signal output end, and the signal compensation module is used to generate a first compensation signal to compensate for the first leakage signal generated by the first switch unit when the first switch unit is turned off, and generate a second compensation signal to compensate for the second leakage signal generated by the second switch unit when the second switch unit is turned off.

[0009] In one or more embodiments of the present invention, the first switch unit includes one or multiple first switch tubes connected in series, the multiple first switch tubes connected in series form the first end and the second end of the first switch unit, and the control end of each first switch tube is used to receive a control signal;

[0010] The second switch unit includes one or multiple second switch tubes connected in series. The multiple second switch tubes connected in series form the first end and the second end of the second switch unit. The control end of each second switch tube is used to receive a control signal.

[0011] In one or more embodiments of the present invention, the first switching unit further includes a first bias unit, and the control end of each of the first switching tubes receives a control signal through the first bias unit. The second switching unit further includes a second bias unit, and the control end of each of the second switching tubes receives a control signal through the second bias unit.

[0012] In one or more embodiments of the present invention, the first bias unit includes one or more first resistors connected in series and / or in parallel, and the second bias unit includes one or more second resistors connected in series and / or in parallel.

[0013] In one or more embodiments of the present invention, the first switch unit further includes a first isolation unit, and the substrate of each of the first switch tubes is connected to the ground voltage through the first isolation unit; the second switch unit further includes a second isolation unit, and the substrate of each of the second switch tubes is connected to the ground voltage through the second isolation unit.

[0014] In one or more embodiments of the present invention, the first isolation unit includes one or more third resistors connected in series and / or in parallel, and the second isolation unit includes one or more fourth resistors connected in series and / or in parallel.

[0015] In one or more embodiments of the present invention, the signal compensation module includes a first compensation unit and a second compensation unit, the first end of the first compensation unit is connected to the first end of the first switch unit, the second end of the first compensation unit is connected to the second end of the second switch unit to generate a second compensation signal, the first end of the second compensation unit is connected to the first end of the second switch unit, and the second end of the second compensation unit is connected to the second end of the first switch unit to generate the first compensation signal.

[0016] In one or more embodiments of the present invention, the first compensation unit includes one or more first capacitors connected in series and / or in parallel; the second compensation unit includes one or more second capacitors connected in series and / or in parallel.

[0017] In one or more embodiments of the present invention, the first capacitor is a ceramic capacitor, a MOM capacitor or a MOS capacitor, and / or the second capacitor is a ceramic capacitor, a MOM capacitor or a MOS capacitor.

[0018] The utility model also discloses a chip, comprising the differential radio frequency switch circuit.

[0019] Compared with existing technologies, the differential RF switch circuit and chip of this utility model significantly improves isolation across a wide bandwidth by simply adding a signal compensation module, with minimal impact on switch insertion loss. Furthermore, due to the minimal number of additional components, the circuit is simple, flexible in design, easy to implement, and requires minimal circuit area, resulting in low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are only some of the embodiments described in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without inventive efforts.

[0021] Figure 1 This is a circuit schematic diagram of a differential RF switch circuit in one embodiment of the present invention.

[0022] Figure 2 Schematic diagram of the connection between the first capacitor and the second capacitor in one embodiment of the present invention.

[0023] Figure 3 1 is an equivalent circuit diagram of a differential RF switch circuit in one embodiment of the present invention.

[0024] Figure 4This is a frequency response curve diagram of a differential RF switch circuit in one embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only a portion of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0026] The terms "coupled," "connected," or "connected" as used in this specification encompass both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as an electrically conductive medium, which may have parasitic inductance or capacitance. An indirect connection may also include a connection through other active or passive devices, such as switches, follower circuits, or other circuits or components, to achieve the same or similar functional objectives. Furthermore, in utility models, terms such as "first" and "second" are primarily used to distinguish one technical feature from another and do not necessarily require or imply a specific relationship, quantity, or order between these technical features.

[0027] like Figure 1 As shown, the differential RF switch circuit in one embodiment of the present invention includes a first switch unit 1 , a second switch unit 2 and a signal compensation module 3 .

[0028] The first end of the first switch unit 1 is connected to the differential signal input terminal Vin+, and the second end of the first switch unit 1 is connected to the differential signal output terminal Vout+. The first switch unit 1 is used to control the connection and disconnection between the differential signal input terminal Vin+ and the differential signal output terminal Vout+ based on a control signal. The first end of the second switch unit 2 is connected to the differential signal input terminal Vin-, and the second end of the second switch unit 2 is connected to the differential signal output terminal Vout-. The second switch unit 2 is used to control the connection and disconnection between the differential signal input terminal Vin- and the differential signal output terminal Vout- based on a control signal.

[0029] The signal compensation module 3 is connected to the first switch unit 1 and the second switch unit 2. The signal compensation module 3 is used to generate a first compensation signal to compensate for the first leakage signal generated by the first switch unit 1 when the first switch unit 1 is turned off, and to generate a second compensation signal to compensate for the second leakage signal generated by the second switch unit 2 when the second switch unit 2 is turned off.

[0030] Specifically, the first switch unit 1 includes one or more first switching transistors M1 connected in series, a first bias unit, and a first isolation unit. The multiple first switching transistors M1 connected in series form the first and second ends of the first switch unit 1. The control end of each first switching transistor M1 receives a control signal through a corresponding first bias unit, or the control ends of all first switching transistors M1 receive a control signal through a first bias unit. The substrate of each first switching transistor M1 is connected to a ground voltage through a corresponding first isolation unit, or the substrates of all first switching transistors M1 are connected to a ground voltage through a first isolation unit.

[0031] Each first bias unit includes one or more first resistors R1 connected in series and / or in parallel, and each first isolation unit includes one or more third resistors R3 connected in series and / or in parallel. In one embodiment, a first switch tube M1, a first resistor R1, and a third resistor R3 are provided as an example for description. The first end of the first switch tube M1 is used to form the first end of the first switch unit 1, and the second end of the first switch tube M1 is used to form the second end of the first switch unit 1. The control end of the first switch tube M1 is connected to the first end of the first resistor R1, and the second end of the first resistor R1 is used to receive a control signal. The substrate of the first switch tube M1 is connected to the first end of the third resistor R3, and the second end of the third resistor R3 is connected to the ground voltage. In other embodiments, the number of first switch tubes M1, first resistor R1, and third resistor R3 can be increased as needed.

[0032] The control terminal of the first switching transistor M1 receives a control signal through a first resistor R1. The substrate of the first switching transistor M1 is connected to ground via a third resistor R3. The first and third resistors R1 and R3 provide bias for the switching circuit. The large resistors R1 and R3 provide isolation to reduce the equivalent parasitic capacitance of the switching circuit.

[0033] The second switch unit 2 includes one or more second switching transistors M2 connected in series, a second bias unit, and a second isolation unit. The number of second bias units and second isolation units can be adjusted as needed. The multiple second switching transistors M2 connected in series form the first and second ends of the second switch unit. The control end of each second switching transistor M2 receives a control signal through a corresponding second bias unit, or the control ends of all second switching transistors M2 receive a control signal through a second bias unit. The substrate of each second switching transistor M2 is connected to ground via a corresponding second isolation unit, or the substrates of all second switching transistors M2 are connected to ground via a first isolation unit.

[0034] Each second bias unit includes one or more second resistors R2 connected in series and / or in parallel, and each second isolation unit includes one or more fourth resistors R4 connected in series and / or in parallel.

[0035] In one embodiment, a second switching transistor M2, a second resistor R2, and a fourth resistor R4 are provided as an example. The first end of the second switching transistor M2 forms the first end of the second switch unit 2, and the second end of the second switching transistor M2 forms the second end of the second switch unit 2. The control end of the second switching transistor M2 is connected to the first end of the second resistor R2, and the second end of the second resistor R2 is used to receive a control signal. The substrate of the second switching transistor M2 is connected to the first end of the fourth resistor R4, and the second end of the fourth resistor R4 is connected to the ground voltage. In other embodiments, the number of second switching transistors M2, second resistors R2, and fourth resistors R4 can be increased as needed.

[0036] The control terminal of the second switch M2 receives a control signal through a second resistor R2. The substrate of the second switch M2 is connected to ground via a fourth resistor R4. The second and fourth resistors R2 and R4 provide bias for the switch circuit. The large resistors R2 and R4 provide isolation to reduce the equivalent parasitic capacitance of the switch circuit.

[0037] In one embodiment, the first switching transistor M1 and the second switching transistor M2 are both N-channel MOS transistors. The first end of the first switching transistor M1 and the first end of the second switching transistor M2 serve as sources, the second end of the first switching transistor M1 and the second end of the second switching transistor M2 serve as drains, and the control end of the first switching transistor M1 and the control end of the second switching transistor M2 serve as gates. The control signals specifically include a first control signal and a second control signal. The second end of the first resistor R1 is configured to receive the first control signal, and the second end of the second resistor R2 is configured to receive the second control signal. The first and second control signals can be synchronous or asynchronous signals.

[0038] In other embodiments, the first switch transistor M1 and the second switch transistor M2 may be P-channel MOS transistors or other types of transistors, and their connection methods may be adaptively adjusted.

[0039] In one embodiment, the first switch unit 1 and the second switch unit 2 are symmetrical to each other, that is, the parameters of the first switch tube M1 and the second switch tube M2 are the same, the parameters of the first resistor R1 and the second resistor R2 are the same, and the parameters of the third resistor R3 and the fourth resistor R4 are the same.

[0040] In other embodiments, the first switch unit 1 and the second switch unit 2 may also be other switch circuits.

[0041] like Figure 1As shown, the signal compensation module 3 includes a first compensation unit and a second compensation unit. The first end of the first compensation unit is connected to the first end of the first switch unit 1, and the second end of the first compensation unit is connected to the second end of the second switch unit 2 to generate a second compensation signal. The first end of the second compensation unit is connected to the first end of the second switch unit 2, and the second end of the second compensation unit is connected to the second end of the first switch unit 1 to generate a first compensation signal.

[0042] Specifically, the first compensation unit includes a first capacitor C1, wherein the first end of the first capacitor C1 is used to form the first end of the first compensation unit, and the second end of the first capacitor C1 is used to form the second end of the first compensation unit. The second compensation unit includes a second capacitor C2, wherein the first end of the second capacitor C2 is used to form the first end of the second compensation unit, and the second end of the second capacitor C2 is used to form the second end of the second compensation unit.

[0043] In one embodiment, only one first capacitor C1 and one second capacitor C2 are provided. Preferably, the capacitance value of the first capacitor C1 is equal to the equivalent capacitance when the second switch unit 2 is turned off, and the capacitance value of the second capacitor C2 is equal to the equivalent capacitance when the first switch unit 1 is turned off, so as to achieve the best compensation effect. In other embodiments, the capacitance value of the first capacitor C1 may be greater than or less than the equivalent capacitance when the second switch unit 2 is turned off, and the capacitance value of the second capacitor C2 may be greater than or less than the equivalent capacitance when the first switch unit 1 is turned off.

[0044] The capacitor types of the first capacitor C1 and the second capacitor C2 include, but are not limited to, ceramic capacitors, MOM capacitors (interdigital capacitors), and MOS capacitors (capacitors composed of MOS transistors). The specific capacitor type can be determined according to the usage scenario. For example, ceramic capacitors can be selected in board-level circuit design, and MOM capacitors or MOS capacitors can be used in integrated circuit design. In other embodiments, other capacitor circuits that can be equivalent to capacitors can also be used.

[0045] like Figure 2 As shown, when a MOS capacitor is used as the first capacitor C1, the gate of the MOS capacitor forms the first end of the first capacitor C1, and the drain and source of the MOS capacitor are connected and form the second end of the first capacitor C1. When a MOS capacitor is used as the second capacitor C2, its connection method is the same as the connection method of the first capacitor C1.

[0046] In other embodiments, multiple first capacitors C1 and / or second capacitors C2 may be provided, and multiple first capacitors C1 and / or second capacitors C2 may be connected in series and / or in parallel with each other, but it is required that the total capacitance value of the multiple first capacitors C1 connected in series and / or in parallel is equal to the capacitance value of the equivalent capacitance of the second switch unit 2 when the second switch unit 2 is turned off, and the total capacitance value of the multiple second capacitors C2 connected in series and / or in parallel is equal to the capacitance value of the equivalent capacitance of the first switch unit 1 when the first switch unit 1 is turned off.

[0047] like Figure 3 As shown, when the first control signal is at a low level and the first and second switches M1 and M2 are turned off, the first and second switches M1 and M2 can be roughly regarded as an equivalent off-resistance Roff connected in parallel with an equivalent capacitance Coff. The equivalent off-resistance Roff has a large value and can effectively isolate the signal. However, the resistance of the equivalent off-resistance Roff is not infinite, so signal leakage still occurs. Moreover, the presence of the equivalent capacitance Coff causes more severe signal leakage from the differential signal input to the differential signal output, deteriorating the isolation.

[0048] At this time, the second capacitor C2 couples the signal of the differential signal input terminal Vin- to the differential signal output terminal Vout+ and generates a first compensation signal, thereby offsetting the signal leakage caused by the equivalent capacitance Coff of the first switch tube M1, achieving neutralization compensation for the equivalent capacitance Coff of the first switch tube M1, and improving the isolation of the first switch tube M1.

[0049] At the same time, since the capacitance value of the second capacitor C2 is equal to the equivalent capacitance Coff when the first switch unit 1 is turned off, the first leakage signal is fully compensated and the best isolation effect is achieved.

[0050] Similarly, the second compensation signal generated by the first capacitor C1 also plays a role in completely offsetting the second leakage signal, thereby achieving neutralization compensation for the equivalent capacitance of the second switch tube M2 and improving the isolation of the second switch tube M2.

[0051] like Figure 4 As shown in FIG1 , the differential RF switch without the signal compensation module 3 in the conventional solution has an isolation of 13.2 dB at 20 GHz and an insertion loss of 1.54 dB. The differential RF switch circuit in this embodiment achieves an isolation of -42.6 dB at 20 GHz and an insertion loss of 1.84 dB, achieving a performance improvement of about 30 dB in isolation, while the insertion loss increases by only 0.3 dB. As can be seen from the frequency response curve, the isolation is effectively improved over a wide bandwidth. In addition, since the signal compensation module 3 only includes two additional capacitors, the increase in layout area can be ignored, which is beneficial to cost control.

[0052] An embodiment of the present invention further provides a chip, comprising the above-mentioned differential radio frequency switch circuit.

[0053] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed within the present invention. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0054] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A differential radio frequency switching circuit, characterized in that: The device comprises a first switch unit, a second switch unit, and a signal compensation module, wherein the first end of the first switch unit and the first end of the second switch unit are connected to the differential signal input end, the second end of the first switch unit and the second end of the second switch unit are connected to the differential signal output end, the first switch unit and the second switch unit are used to control the connection and disconnection between the differential signal input end and the corresponding differential signal output end based on a control signal, the signal compensation module is connected to the differential signal input end and the differential signal output end, and the signal compensation module is used to generate a first compensation signal to compensate for a first leakage signal generated by the first switch unit when the first switch unit is turned off, and generate a second compensation signal to compensate for a second leakage signal generated by the second switch unit when the second switch unit is turned off; The first switch unit includes one or multiple first switch tubes connected in series, the multiple first switch tubes connected in series form a first end and a second end of the first switch unit, and a control end of each first switch tube is used to receive a control signal; The second switch unit includes one or multiple second switch tubes connected in series, the multiple second switch tubes connected in series form a first end and a second end of the second switch unit, and a control end of each second switch tube is used to receive a control signal; The first switch unit further includes a first bias unit, and the control end of each first switch tube receives a control signal through the first bias unit. The second switch unit further includes a second bias unit, and the control end of each second switch tube receives a control signal through the second bias unit. The first switch unit further includes a first isolation unit, through which the substrate of each first switch tube is connected to the ground voltage. The second switch unit further includes a second isolation unit, through which the substrate of each second switch tube is connected to the ground voltage.

2. The differential RF switch circuit according to claim 1, wherein: The first bias unit includes one or more first resistors connected in series and / or in parallel, and the second bias unit includes one or more second resistors connected in series and / or in parallel.

3. The differential RF switch circuit according to claim 1, wherein: The first isolation unit includes one or more third resistors connected in series and / or in parallel, and the second isolation unit includes one or more fourth resistors connected in series and / or in parallel.

4. The differential RF switch circuit according to claim 1, wherein: The signal compensation module includes a first compensation unit and a second compensation unit, the first end of the first compensation unit is connected to the first end of the first switch unit, the second end of the first compensation unit is connected to the second end of the second switch unit to generate a second compensation signal, the first end of the second compensation unit is connected to the first end of the second switch unit, and the second end of the second compensation unit is connected to the second end of the first switch unit to generate the first compensation signal.

5. The differential RF switch circuit according to claim 4, characterized in that: The first compensation unit includes one or more first capacitors connected in series and / or in parallel; the second compensation unit includes one or more second capacitors connected in series and / or in parallel.

6. The differential RF switch circuit according to claim 5, characterized in that: The first capacitor is a ceramic capacitor, a MOM capacitor or a MOS capacitor, and / or the second capacitor is a ceramic capacitor, a MOM capacitor or a MOS capacitor.

7. A chip, characterized in that: The invention comprises the differential radio frequency switch circuit according to any one of claims 1 to 6.

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