A broadband semiconductor radio frequency switch based on a coupled T-shaped inductor

Abstract

The present invention discloses a broadband semiconductor radio frequency switch based on a coupled T-shaped inductor, belonging to the technical field of basic electronic circuits. The switch includes: a first radio frequency port, a second radio frequency port, and a multi-stage topology connected between the first radio frequency port and the second radio frequency port. Each stage of the topology includes: a first DC port, a second DC port, a first transistor, a second transistor, a first matching circuit, a second matching circuit, a third matching circuit, a fourth matching circuit, and a coupled T-shaped inductor unit. Two transmission poles are formed by the coupled T-shaped inductor unit and two transistors. By controlling the coupling distance between the coupled inductors, the inductance value of the coupled inductors themselves, and the inductance value of the grounded inductor, the working bandwidth of the switch can be broadened while achieving a large coupling degree.

Description

Technical Field

[0001] The present invention relates to a semiconductor radio frequency switch, and specifically discloses a broadband semiconductor radio frequency switch based on a coupled T-shaped inductor, which relates to radio frequency integrated circuit design technology and belongs to the technical field of basic electronic circuits. Background Art

[0002] A radio frequency switch is a control circuit and is widely used in fields such as communication, radar, and detection. The switch based on a field effect transistor has the advantage of low power consumption due to its small gate current. According to different designs of the coupling circuit between transistors, the existing semiconductor switches are as follows: The first is to load a transmission line with a length of λ / 4 between transistors to achieve broadband matching. However, since multiple λ / 4 transmission lines are used for impedance transformation in this method, the size is relatively large. The second is to load transistors on coupled lines and achieve broadband matching through the mutual coupling between the coupled lines. However, in this method, the degree of freedom for adjusting the coupling degree of the semiconductor switch is not high enough, and it is difficult to balance the isolation and the matching bandwidth well.

[0003] In summary, the existing semiconductor switches need to be improved in the following three aspects: (1) How to miniaturize the coupling circuit between transistors; (2) How to improve the design freedom of the coupling circuit between transistors, so as to provide an optimization space for improving the performance of semiconductor switches such as bandwidth and isolation; (3) How to achieve a large coupling degree and broaden the switch bandwidth. Summary of the Invention

[0004] The invention purpose of the present invention is to aim at the deficiencies of the above background art, and provide a broadband semiconductor radio frequency switch based on a coupled T-shaped inductor, so as to solve the technical problems of the large size of the coupling circuit between transistors and the difficulty in adjusting the coupling degree, and achieve the invention purposes of switch miniaturization and bandwidth broadening.

[0005] The present invention adopts the following technical solutions to achieve the above invention purposes:

[0006] A broadband semiconductor radio frequency switch based on a coupled T-type inductor, comprising: a first radio frequency port, a second radio frequency port, and a multi-stage topology connected between the first radio frequency port and the second radio frequency port. Each stage of the topology includes: a first DC port, a second DC port, a first transistor, a second transistor, a first matching circuit, a second matching circuit, a third matching circuit, a fourth matching circuit, and a coupled T-type inductor unit. The first radio frequency port is electrically connected to one end of the first matching circuit. The other end of the first matching circuit is connected to the drain of the first transistor and one end of the third matching circuit. The source of the first transistor is grounded. The gate of the first transistor is connected to the first DC port. The other end of the third matching circuit is connected to the left end of the coupled T-type inductor unit. The right end of the coupled T-type inductor unit is electrically connected to one end of the fourth matching circuit. The other end of the fourth matching circuit is electrically connected to the drain of the second transistor and one end of the second matching circuit. The other end of the second matching circuit is connected to the second radio frequency port. The gate of the second transistor is connected to the second DC port;

[0007] Wherein, the coupled T-type inductor unit is composed of two mutually coupled first inductors, a second inductor, and a grounded inductor. The first inductor and the second inductor are connected in series. The non-grounded end of the grounded inductor is connected to the connection point of the first inductor and the second inductor. The other end of the grounded inductor is grounded. The free ends of the first inductor and the second inductor are respectively the two ends of the coupled T-type inductor. The free end of the first inductor is the left end of the coupled T-type inductor, and the free end of the second inductor is the right end of the coupled T-type inductor.

[0008] As a further optimization scheme of a broadband semiconductor radio frequency switch based on a coupled T-type inductor, the first matching circuit and the second matching circuit are circuits composed of pure inductors, pure capacitors, or a combination of capacitors and inductors; the third matching circuit and the fourth matching circuit are pure inductors, pure capacitors, or short circuits.

[0009] As a further optimization scheme of a broadband semiconductor radio frequency switch based on a coupled T-type inductor, the DC port is connected to the DC bias voltage through a gate resistor.

[0010] As a further optimization scheme of a broadband semiconductor radio frequency switch based on a coupled T-type inductor, the first inductor, the second inductor, the grounded inductor, the inductor in the first matching circuit, the inductor in the second matching circuit, the inductor in the third matching circuit, and the inductor in the fourth matching circuit that make up the coupled T-type inductor unit are microstrip line inductors, stripline inductors, or spiral inductors.

[0011] As a further optimization scheme of a broadband semiconductor radio frequency switch based on a coupled T-type inductor, the capacitor in the first matching circuit, the capacitor in the second matching circuit, the capacitor in the third matching circuit, and the capacitor in the fourth matching circuit are metal-insulator-metal capacitors, metal-oxide-metal capacitors, parallel plate capacitors, or interdigital capacitors.

[0012] As a further optimization solution for a broadband semiconductor radio frequency switch based on a coupled T-shaped inductor, the first transistor and the second transistor are field effect transistors, high electron mobility transistors, mHEMT transistors, or pHEMT transistors.

[0013] The present invention adopts the above technical solution and has the following beneficial effects:

[0014] (1) The broadband semiconductor radio frequency switch disclosed by the present invention uses a coupled T-shaped inductor as the coupling circuit between transistors, abandoning the traditional method of loading a λ / 4 transmission line to achieve broadband matching, and ensuring the miniaturization of the switch.

[0015] (2) The two inductors included in the coupled T-shaped inductor adopted by the broadband semiconductor radio frequency switch disclosed by the present invention respectively form a transmission pole with a parallel transistor. By utilizing the characteristic of the coupled T-shaped inductor having multiple design variables, by controlling the coupling distance between the coupled inductors, the inductance value of the coupled inductor itself, and the inductance value of the grounded inductor, it is possible to ensure a relative bandwidth of more than 50% in the on state of the switch while achieving a large coupling degree, that is, to achieve the purpose of broadening the working bandwidth of the switch. Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of a broadband semiconductor radio frequency switch based on a coupled T-shaped inductor provided by Embodiment 1 of the present invention.

[0017] Figure 2 It is a simulation curve graph of the relationship between the scattering parameters and the frequency of Embodiment 1 of the present invention.

[0018] Figure 3 It is a schematic structural diagram of a broadband semiconductor radio frequency switch based on a coupled T-shaped inductor provided by Embodiment 2 of the present invention.

[0019] Figure 4 It is a schematic structural diagram of a broadband semiconductor radio frequency switch based on a coupled T-shaped inductor provided by Embodiment 3 of the present invention.

[0020] Figure 5 It is a circuit diagram of the general form of a broadband semiconductor radio frequency switch based on a coupled T-shaped inductor provided by the present invention.

[0021] Description of reference numerals in the figure: P1, the first radio frequency port; P2, the second radio frequency port; K1 and K3, the first DC ports; K2 and K4, the second DC ports; 101, the first matching inductor; 103, the second matching inductor; 201 and 501, the first transistors; 202, the third matching inductor; 203 and 503, the first inductors; 204 and 504, the first gate resistors; 301 and 601, the second transistors; 302, the fourth matching inductor; 303 and 603, the second inductors; 304 and 604, the second gate resistors; 401 and 701, the ground inductors; 11, the first matching circuit; 12, the second matching circuit; 21, the third matching circuit; 22, the fourth matching circuit. Detailed implementation manners

[0022] The technical solution of the invention will be described in detail below with reference to the accompanying drawings.

[0023] The general form of the broadband semiconductor radio frequency switch based on the coupled T-shaped inductor proposed by the present invention is as Figure 5 shown, including: the first radio frequency port P1, the second radio frequency port P2, the first DC port K1, the second DC port K2, the first transistor 201, the second transistor 301, the first matching circuit 11, the second matching circuit 12, the third matching circuit 21, the fourth matching circuit 22, and a coupled T-shaped inductor unit; wherein, the coupled T-shaped inductor unit is composed of two mutually coupled first inductors 203, second inductors 303 and a ground inductor 401. The mutually coupled first inductors 203 and second inductors 303 are connected in series, and the free end of the first inductor 203 is the left end P L of the coupled T-shaped inductor unit, the free end of the second inductor 303 is the right end P R of the coupled T-shaped inductor unit, one end of the ground inductor 401 is electrically connected to the connection point of the first inductor 203 and the second inductor 303, and the other end of the ground inductor 401 is grounded.

[0024] The first radio frequency port P1 is electrically connected to one end of the first matching circuit 11, the other end of the first matching circuit 11 is electrically connected to the drain of the first transistor 201, and the source of the first transistor 201 is grounded. The first matching circuit 11 is connected in series with the third matching circuit 21, that is, the other end of the first matching circuit 11 is electrically connected to one end of the third matching circuit 21, and the other end of the third matching circuit 21 is electrically connected to the left end P L of the coupled T-shaped unit. The right end P Ris electrically connected to one end of the fourth matching circuit 22. The fourth matching circuit 22 is connected in series with the second matching circuit 12, that is, the other end of the fourth matching circuit 22 is electrically connected to one end of the second matching circuit 12, and the other end of the second matching circuit 12 is electrically connected to the second radio frequency port P2. The drain of the second transistor 301 is electrically connected to the connection point of the second matching circuit 12 and the fourth matching circuit 22. The source of the second transistor 301 is grounded. The gate of the first transistor 201 is connected to the first DC port K1, and the gate of the second transistor 301 is connected to the second DC port K2.

[0025] The first matching circuit and the second matching circuit are circuits composed of pure inductors, pure capacitors, or capacitors and inductors. The third matching circuit and the fourth matching circuit are pure inductors, pure capacitors, or short circuits. Specific Embodiment 1

[0027] A broadband semiconductor radio frequency switch based on a coupled T-shaped inductor is as Figure 1 shown. On the basis of the general form shown in Figure 5 the first matching inductor 101 is selected as the first matching circuit, the second matching inductor 103 is selected as the second matching circuit, the third matching inductor 202 is selected as the third matching circuit, and the fourth matching inductor 302 is selected as the fourth matching circuit. The gate of the first transistor 201 is electrically connected to one end of the first gate resistor 204, and the other end of the first gate resistor 204 is electrically connected to the first DC port K1. The gate of the second transistor 301 is electrically connected to one end of the second gate resistor 304, and the other end of the second gate resistor 304 is electrically connected to the second DC port K2.

[0028] The inductance value of the first coupled inductor 101 is 0.01 fF and is realized by a microstrip line with a length of 15 μm and a width of 20 μm; the inductance value of the second coupled inductor 103 is 0.01 fF and is realized by a microstrip line with a length of 15 μm and a width of 20 μm; the inductance value of the first matching inductor 202 is 0.041 fF and is realized by a microstrip line with a length of 60 μm and a width of 20 μm; the inductance value of the second matching inductor 302 is 0.041 fF and is realized by a microstrip line with a length of 60 μm and a width of 20 μm; the inductance values of the first inductor 203 and the second inductor 303 in the coupled T-shaped inductor are 0.107 fF and are realized by a microstrip line with a length of 150 μm and a width of 20 μm. The distance between the first inductor 203 and the second inductor 303 in the coupled T-shaped inductor is 30 μm.

[0029] The logic levels accessed by the first DC port K1 and the second DC port K2 are the same. When both the first transistor 201 and the second transistor 301 are turned on, the first inductor 203 and the first transistor 201 form a transmission pole, and the second inductor 303 and the second transistor 301 form a transmission pole. By adjusting the coupling distance between the first inductor and the second inductor, the inductance values of the first inductor and the second inductor themselves, and the inductance value of the grounding inductor, a large coupling degree of the semiconductor radio frequency switch is achieved.

[0030] Figure 2 It is a simulation curve graph showing the relationship between the scattering parameters and frequency of the broadband semiconductor radio frequency switch shown in Specific Embodiment 1 of the present invention. As Figure 2 shown, the center frequency of the switch disclosed in Embodiment 1 of the present invention is 42 GHz, the two transmission poles are respectively at 37 GHz and 49 GHz, the insertion loss is less than 1 dB, the return loss is greater than 20 dB, and the relative bandwidth has exceeded 100%. Compared with the prior art, the switch provided in Embodiment 1 of the present invention has a significantly improved return loss, an extremely wide bandwidth, and a very small size. Specific Embodiment 2

[0032] A broadband semiconductor radio frequency switch based on a coupled T-shaped inductor involved in this embodiment is as Figure 3 shown. On the basis of the general form shown in Figure 5 , the first matching inductor 101 is selected as the first matching circuit, the second matching inductor 103 is selected as the second matching circuit, the short circuit line is selected as the third matching circuit, and the short circuit line is selected as the fourth matching circuit. Specific Embodiment 3

[0034] A broadband semiconductor radio frequency switch based on a coupled T-shaped inductor involved in this embodiment is as Figure 4 shown. On the basis of the general form shown in Figure 5 , it includes a topological structure of two-stage T-shaped coupled inductors coupled with parallel transistors. In the first-stage topological structure, the first matching inductor 101 is selected as the first matching circuit, the matching inductor is selected as the second matching circuit, the third matching inductor 202 is selected as the third matching circuit, and the fourth matching inductor 302 is selected as the fourth matching circuit; in the second-stage topological structure, the matching inductor is selected as the first matching circuit, the second matching inductor 103 is selected as the second matching circuit, the third matching inductor 502 is selected as the third matching circuit, and the fourth matching inductor 602 is selected as the fourth matching circuit. The connection manner of the T-shaped coupled inductor composed of the first transistor 501, the second transistor 601, the first inductor 503, the second inductor 603, and the grounding inductor 701 is the same as that of the first stage. The second matching circuit in the first-stage topological structure and the first matching circuit in the second-stage topological structure can be realized by an inductor 102.

[0035] The logic levels connected to the first DC port K3 and the second DC port K4 in the second-level topology are the same as those connected to the first DC port K1 and the second DC port K2 in the first-level topology. When the first transistor and the second transistor in both levels of the topology are turned on, the first inductor 203 and the first transistor 201 in the first-level topology form a transmission pole, the second inductor 303 and the second transistor 301 in the first-level topology form a transmission pole, the first inductor 503 and the first transistor 501 in the second-level topology form a transmission pole, and the second inductor 603 and the second transistor 601 in the second-level topology form a transmission pole. By adjusting the coupling distance between the first inductor and the second inductor, the inductance values of the first inductor and the second inductor themselves, and the inductance value of the grounded inductor in both levels of the topology, a large coupling degree of the semiconductor radio frequency switch is achieved.

[0036] The above embodiments are only exemplary descriptions of the present invention and do not limit its protection scope. Those skilled in the art can also make partial changes to it. For example, in the first and second matching circuits of the broadband semiconductor radio frequency switch circuit proposed in the present invention, a pure capacitor or a circuit composed of a capacitor and an inductor can be selected. The third and fourth matching circuits can also select a pure inductor or a pure capacitor. Moreover, the topology of multiple-stage T-type coupled inductors and parallel transistors can be further expanded to introduce more transmission poles. Any form of equivalent substitution that conforms to the purpose of the invention falls within the protection scope of the present invention.

Claims

1. A broadband semiconductor radio frequency switch based on a coupled T-shaped inductor, characterized in that Including: A first radio frequency port, a second radio frequency port, and a multi-stage topology connected between the first radio frequency port and the second radio frequency port. Each stage of the topology includes: a first DC port, a second DC port, a first transistor, a second transistor, a first matching circuit, a second matching circuit, a third matching circuit, a fourth matching circuit, and a coupled T-shaped inductor unit. The first radio frequency port is electrically connected to one end of the first matching circuit. The drain of the first transistor is electrically connected to the other end of the first matching circuit and one end of the third matching circuit. The source of the first transistor is grounded. The gate of the first transistor is connected to the first DC port. The other end of the third matching circuit is electrically connected to the left end of the coupled T-shaped inductor unit. The right end of the coupled T-shaped inductor unit is electrically connected to one end of the fourth matching circuit. The other end of the fourth matching circuit is electrically connected to the drain of the second transistor and one end of the second matching circuit. The source of the second transistor is grounded. The gate of the second transistor is connected to the second DC port. The other end of the second matching circuit is connected to the second radio frequency port; Wherein, the coupled T-shaped inductor unit includes: a grounding inductor, a first inductor and a second inductor that are mutually coupled. One end of the first inductor is the left end of the coupled T-shaped inductor unit. The other end of the first inductor is connected to one end of the second inductor. The other end of the second inductor is the right end of the coupled T-shaped inductor unit. One end of the grounding inductor is electrically connected to the connection point of the first inductor and the second inductor. The other end of the grounding inductor is grounded.

2. The broadband semiconductor radio frequency switch based on a coupled T-shaped inductor according to claim 1, characterized in that The first matching circuit and the second matching circuit are circuits composed of pure inductance, pure capacitance, or a combination of capacitance and inductance; the third matching circuit and the fourth matching circuit are pure inductance, pure capacitance, or short circuits.

3. A broadband semiconductor radio frequency switch based on a coupled T-shaped inductor according to claim 1, characterized in that, The DC port is connected to a DC bias voltage through a gate resistor.

4. The broadband semiconductor radio frequency switch based on a coupled T-type inductor according to claim 2, wherein The first inductor, the second inductor, the grounding inductor, the inductor in the first matching circuit, the inductor in the second matching circuit, the inductor in the third matching circuit, and the inductor in the fourth matching circuit are microstrip line inductors, stripline inductors, or spiral inductors.

5. The broadband semiconductor radio frequency switch based on a coupled T-shaped inductor according to claim 2, wherein, The capacitor in the first matching circuit, the capacitor in the second matching circuit, the capacitor in the third matching circuit, and the capacitor in the fourth matching circuit are metal-insulator-metal capacitors, metal-oxide-metal capacitors, parallel plate capacitors, or interdigital capacitors.

6. The broadband semiconductor radio frequency switch based on a coupled T-type inductor according to claim 1, wherein The transistor is a field effect transistor, a high electron mobility transistor, an mHEMT, or a pHEMT transistor.

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