CN-121547036-B - High-isolation radio frequency switch circuit based on parasitic parameter compensation

CN121547036BCN 121547036 BCN121547036 BCN 121547036BCN-121547036-B

Abstract

The invention discloses a high-isolation radio frequency switch circuit based on parasitic parameter compensation, and belongs to the technical field of radio frequency switch circuits. The circuit comprises an input end, a first output end, a second output end, two impedance transformation sections, two output transmission lines and two parallel branches, wherein the input end is respectively connected to one ends of the two impedance transformation sections through a common node, the other ends of the impedance transformation sections are respectively connected to a T-shaped junction node, each T-shaped junction node is respectively connected to the first output end and the second output end through the output transmission lines, one end of each parallel branch is connected to the T-shaped junction node, each parallel branch comprises a compensation stub and a PIN diode which are connected in series, and a microstrip line structure at each T-shaped junction node is configured to introduce a parallel capacitor so as to form parallel resonance with the parallel branch in a conducting state.

Inventors

LI PAN
Duan Chuangwei
LIAO GUISHENG
YANG LIXIA
PAN XUELI
FANG HUI

Assignees

安徽大学

Dates

Publication Date: 20260508
Application Date: 20260121

Claims (7)

1. The radio frequency switch circuit based on parasitic parameter compensation is characterized by comprising an input end, a first output end, a second output end, two impedance transformation sections, two output transmission lines and two parallel branches; the input end is respectively connected to one ends of the two impedance transformation sections through a common node, and the other ends of the impedance transformation sections are respectively connected to a T-shaped junction node; one end of the parallel branch is connected to the T-shaped junction node, and the other end of the parallel branch is grounded; the parallel branch comprises a compensation stub and a PIN diode which are connected in series, wherein one end of the compensation stub is connected with the junction of the impedance transformation section and the output transmission line to form the T-shaped junction node, and the other end of the compensation stub is connected with the anode or the cathode of the PIN diode; the microstrip line structure at the T-shaped junction node is configured to introduce a parallel capacitance to form a parallel resonance with the parallel branch in a conducting state; The included angle formed by the compensation stub, the impedance transformation section and the output transmission line is a right angle, no corner cutting structure is arranged on the inner side of the right angle, and an equivalent parallel capacitor to the ground is constructed by utilizing an edge electric field generated by discontinuous metal area at the intersection of microstrip lines ; The T-shaped junction node main transmission line is provided with a metal patch to be widened locally to form a low-impedance step line segment, and an extra parallel step capacitor is introduced 。
2. The parasitic parameter compensation based radio frequency switching circuit of claim 1, wherein the length of the impedance transformation section is one quarter of the wavelength of the guided wave corresponding to the operating frequency.
3. The radio frequency switching circuit based on parasitic parameter compensation according to claim 1, wherein the PIN diodes in the two parallel branches are arranged in opposite directions, wherein the positive electrode of the PIN diode in one parallel branch is connected to the compensation stub, the negative electrode is connected to the metal through hole, and the negative electrode of the PIN diode in the other parallel branch is connected to the compensation stub, and the positive electrode is connected to the metal through hole.
4. The parasitic parameter compensation based radio frequency switching circuit of claim 1, further comprising a dc bias line having one end connected to a connection point of the compensation stub and the PIN diode and the other end connected to a dc control voltage source, the dc bias line comprising a high impedance line and a radio frequency choke in series.
5. The radio frequency switch circuit based on parasitic parameter compensation according to claim 3, wherein the radio frequency switch circuit is arranged on a top layer of a dielectric substrate, the ground plane is arranged on a bottom layer of the dielectric substrate, a distance between the circuit and the ground plane is determined by a thickness of the dielectric substrate, and the metal through hole penetrates through the dielectric substrate.
6. A method of designing a parasitic parameter compensation based radio frequency switching circuit according to any one of claims 1 to 5, comprising the steps of: Calculating the characteristic impedance and the electrical length of a compensation stub according to the parasitic capacitance value, the packaging parasitic inductance value and the parasitic inductance value of the metal through hole, so that the inductance provided by the compensation stub and the total impedance of the PIN diode and the metal through hole form series resonance at a T-shaped junction node; under the condition that the characteristic impedance and the electrical length of the compensation stub are fixed, the conduction inductance value of the PIN diode in a conduction state is obtained; Step three, adjusting geometrical parameters of a T-shaped junction node, and introducing an equivalent parallel capacitor to enable the equivalent parallel capacitor and the total equivalent inductance of the parallel branch to form parallel resonance; Wherein the method for introducing the equivalent parallel capacitance comprises the following steps: The included angle formed by the compensation stub, the impedance transformation section and the output transmission line is a right angle, no corner cutting structure is arranged on the inner side of the right angle, and an equivalent parallel capacitor to the ground is constructed by utilizing an edge electric field generated by discontinuous metal area at the intersection of microstrip lines And (C) sum The T-shaped junction node main transmission line is provided with a metal patch to be widened locally to form a low-impedance step line segment, and an extra parallel step capacitor is introduced 。
7. The method of claim 6, wherein in step one, the characteristic impedance of the compensation stub And electric length The following relationship is satisfied: Wherein, the In order for the operating angular frequency to be a function of, For the PIN diode off-state parasitic capacitance, Parasitic inductance is packaged for the PIN diode off-state, Is the parasitic inductance of the metal via, To compensate for the characteristic impedance of the stub, To compensate for the electrical length of the stub; In step three, the parallel resonance satisfies the following relationship: Wherein, the Is the total equivalent inductance of the parallel branch in the on state, And the equivalent parallel capacitance is introduced for adjusting the geometric structure parameter of the T-shaped junction node.

Description

High-isolation radio frequency switch circuit based on parasitic parameter compensation Technical Field The invention relates to the technical field of radio frequency switching circuits, in particular to a high-isolation radio frequency switching circuit based on parasitic parameter compensation. Background Traditional high performance PIN diodes and MEMS switches, while small in parasitic parameters, are expensive and complex to drive and are not suitable for large-scale array applications. In the prior art, a scheme of parasitic compensation by using a printed interdigital capacitor is extremely sensitive to PCB etching precision, the processing error easily causes performance failure, and the working bandwidth is narrower. The switching technology based on the phase change material needs a special film process, cannot be compatible with a standard low-cost PCB process, and has large mass production difficulty. The parasitic parameter effects of low cost commercial PIN diodes at high frequencies are significant, and the lack of effective impedance co-design can lead to severe signal leakage (low isolation) and high insertion loss. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a high-isolation radio frequency switch circuit based on parasitic parameter compensation. The aim of the invention can be achieved by the following technical scheme: The invention relates to a radio frequency switch circuit based on parasitic parameter compensation, which comprises an input end, a first output end, a second output end, two impedance transformation sections, two output transmission lines and two parallel branches, wherein the first output end is connected with the first output end; the input end is respectively connected to one ends of the two impedance transformation sections through a common node, and the other ends of the impedance transformation sections are respectively connected to a T-shaped junction node; one end of the parallel branch is connected to the T-shaped junction node, and the other end of the parallel branch is grounded; the parallel branch comprises a compensation stub and a PIN diode which are connected in series, wherein one end of the compensation stub is connected with the junction of the impedance transformation section and the output transmission line to form the T-shaped junction node, and the other end of the compensation stub is connected with the anode or the cathode of the PIN diode; The microstrip line structure at the T-junction node is configured to introduce a parallel capacitance to form a parallel resonance with the parallel branch in the on state. Optionally, an included angle formed by the compensation stub, the impedance transformation section and the output transmission line is a right angle, and no corner cutting structure is arranged on the inner side of the right angle. Optionally, the impedance transformation section or the output transmission line has a stepped impedance structure in a region adjacent to the T-junction node, the linewidth at the stepped impedance structure being greater than the linewidth of the remainder of the impedance transformation section or the output transmission line to introduce a stepped capacitance. Optionally, the length of the impedance transformation section is a quarter of the wavelength of the guided wave corresponding to the operating frequency. The PIN diodes in the two parallel branches are arranged in opposite directions, wherein the positive electrode of the PIN diode in one parallel branch is connected to the compensation stub, the negative electrode of the PIN diode in the other parallel branch is connected to the metal through hole, the negative electrode of the PIN diode in the other parallel branch is connected to the compensation stub, and the positive electrode of the PIN diode in the other parallel branch is connected to the metal through hole. Optionally, the electronic device further comprises a direct current bias line, wherein one end of the direct current bias line is connected to a connection point of the compensation stub and the PIN diode, the other end of the direct current bias line is connected to a direct current control voltage source, and the direct current bias line comprises a high-impedance line and a radio frequency choke coil which are connected in series. Optionally, the radio frequency switch circuit is disposed on a top layer of the dielectric substrate, the ground plane is disposed on a bottom layer of the dielectric substrate, a distance between the radio frequency switch circuit and the ground plane is determined by a thickness of the dielectric substrate, and the metal through hole penetrates through the dielectric substrate. The second aspect of the present invention relates to a design method of a radio frequency switch circuit based on parasitic parameter compensation, which comprises the following steps: Calculating the characteristic impedance and the el