Fusion method for microwave and millimeter wave monolithic integrated switch and filter

Abstract

The invention discloses a method for fusing a microwave and millimeter wave monolithic integrated switch and a filter, which is characterized in that when the method is used for fusing a single-pole double-throw switch and a band-pass filter, two parallel channels are connected between a signal input end and a signal output end; the first channel comprises a switching circuit, a first capacitance-inductance tuning unit, a first filter and a second capacitance-inductance tuning unit which are connected in series; the second channel comprises a switching circuit, a third capacitance-inductance tuning unit, a second filter and a fourth capacitance-inductance tuning unit which are connected in series, and the four capacitance-inductance tuning units have the same structure; the capacitance-inductance tuning unit is cascaded between the switch and the band-pass filter, and the capacitance is integrated into the design of the switch, so that the frequency band of the switch is widened; a parasitic capacitor and a capacitance and inductance tuning unit existing in the switch are integrated into the design of the band-pass filter, so that the insertion loss, the return loss and the out-of-band rejection of the switch filter bank after integral cascade connection are improved.

Description

Technical Field

[0001] This invention provides a method for the integrated design of microwave and millimeter-wave monolithic integrated switches and filters, belonging to the field of microwave and millimeter-wave monolithic integrated switch filter bank technology. Background Technology

[0002] In multi-band, multi-standard communication systems, signal frequency ranges need to cover several octaves. Therefore, advanced communication systems require reconfigurability to meet various frequencies and communication standards. Existing on-chip passive switches are primarily designed for broadband applications and have significant shortcomings in stopband rejection performance, failing to achieve rapid spectral roll-off. To achieve frequency band selection and out-of-band signal suppression, bandpass filters are typically cascaded with switches, resulting in a small-area, monolithic integrated switching filter bank with low insertion loss, high out-of-band rejection, and switchable frequency capabilities. However, in microwave and millimeter-wave bands, circuit parasitic effects worsen significantly. The parasitic capacitance generated when the MOSFET in the switching circuit is turned off severely limits the frequency characteristics of the subsequent bandpass filter, thus affecting the performance of the entire switching filter bank. Summary of the Invention

[0003] Technical Problem: To overcome the shortcomings of existing technologies, this invention provides a method for integrating monolithic switches and filters for microwave and millimeter-wave applications. In the integration of a single-pole double-throw switch and a bandpass filter, this method cascades a series-connected capacitor and inductor with a capacitor connected in parallel to ground between the switch and the bandpass filter to perform frequency compensation on the single-pole double-throw switch circuit, thereby widening the switch's bandwidth. The parasitic capacitance of the switch circuit and the capacitor-inductor tuning unit are integrated into the design of the bandpass filter, thereby improving the insertion loss, return loss, and out-of-band rejection of the overall cascaded switch filter bank.

[0004] Technical Solution: To achieve the above objectives, the technical solution adopted by the present invention for a method of integrating microwave and millimeter-wave monolithic integrated switches and filters is as follows:

[0005] When this method is used to integrate a single-pole double-throw switch with a bandpass filter, two parallel channels are connected between the signal input and signal output terminals. The first channel includes a series-connected switching circuit, a first capacitor-inductor tuning unit, a first filter, and a second capacitor-inductor tuning unit. The second channel includes a series-connected switching circuit, a third capacitor-inductor tuning unit, a second filter, and a fourth capacitor-inductor tuning unit. The four capacitor-inductor tuning units have the same structure.

[0006] The first channel specifically includes a ninth capacitor, a ninth microstrip line, a first microstrip line, a second microstrip line, a first capacitor-inductor tuning unit, a first filter, a second capacitor-inductor tuning unit, a fifth microstrip line, a sixth microstrip line, a tenth microstrip line, and a tenth capacitor connected in series in sequence; a first switching circuit is connected to both ends of the second microstrip line; and a second switching circuit is connected to both ends of the fifth microstrip line.

[0007] The second channel specifically includes a ninth capacitor, a ninth microstrip line, a third microstrip line, a fourth microstrip line, a third capacitor-inductor tuning unit, a second filter, a fourth capacitor-inductor tuning unit, a seventh microstrip line, an eighth microstrip line, a tenth microstrip line, and a tenth capacitor connected in series in sequence; a third switching circuit is connected to both ends of the fourth microstrip line; and a fourth switching circuit is connected to both ends of the seventh microstrip line.

[0008] In the first switching circuit, the base of the first NMOS transistor is connected to the first power supply through the first resistor, and the collector of the first NMOS transistor is connected to the front end of the second microstrip line; the base of the second NMOS transistor is connected to the first power supply through the second resistor, and the collector of the second NMOS transistor is connected to the rear end of the second microstrip line.

[0009] The first, second, third, and fourth switch circuits have the same structure.

[0010] The first capacitor-inductor tuning unit includes a first capacitor and a first inductor connected in series, and a second capacitor is connected between the first capacitor and the first inductor to ground.

[0011] In the first capacitor-inductor tuning unit, the first capacitor and the second capacitor are plate capacitors with fixed capacitance values, and the first inductor is a square inductor with a fixed inductance value. The plate capacitors and the square inductor together form a T-shaped first capacitor-inductor tuning unit.

[0012] The first capacitor in the first capacitor-inductor tuning unit is used for frequency compensation of the front-end switching circuit, widening the frequency band of the switch; the second capacitor and the first inductor introduce out-of-band transmission zeros for the subsequent bandpass filter, improving the out-of-band rejection capability of the bandpass filter; in the integrated design of the switch and filter, the parasitic capacitances present when the first NMOS transistor and the second NMOS transistor are turned off, along with the first capacitor-inductor tuning unit, are regarded as part of the bandpass filter and integrated into the bandpass filter, improving the insertion loss, return loss, and out-of-band rejection of the overall cascaded dual-channel switching filter bank.

[0013] The first capacitor-inductor tuning unit, the second capacitor-inductor tuning unit, the third capacitor-inductor tuning unit, and the fourth capacitor-inductor tuning unit have the same structure.

[0014] When the first filter and the second filter are Chebyshev type bandpass filters, they are used to integrate single-pole double-throw switches and Chebyshev type bandpass filters. The four capacitor-inductor tuning units are respectively cascaded between two single-pole double-throw switches and two Chebyshev type bandpass filters.

[0015] Beneficial effects: The fusion design method for monolithic integrated switches and filters for microwave and millimeter-wave applications provided by this invention has the following advantages compared with existing technologies:

[0016] 1. One existing method for designing monolithic integrated switching filter banks in the microwave and millimeter-wave bands is to use microstrip lines to design the bandpass filter and to use microstrip lines for matching at the cascade of the switch and the filter. However, this method cannot compensate for the parasitic effects present in the switching circuit, which limits the bandwidth of the switch and makes it difficult to meet the octave band requirement. In addition, using distributed components for design and matching will result in a large chip area and increase the chip manufacturing cost.

[0017] 2. Another existing method for designing monolithic integrated switching filter banks using lumped components involves directly cascading a broadband switch, a high-order low-pass filter, and a high-order high-pass filter, and then adjusting the matching by optimizing the cascade structure. However, this method involves various parameter trade-offs and cannot achieve narrowband, high out-of-band rejection filtering characteristics in the microwave and millimeter-wave frequency bands. In addition, this overall optimization method makes the contribution of each lumped component to the overall switching filter bank unclear, resulting in weak adjustment capability when facing communication systems with different frequency bands, different standards, and requiring reconfiguration. Attached Figure Description

[0018] Figure 1 This is a circuit diagram of a monolithic integrated switching filter bank used in the microwave and millimeter-wave frequency bands in this invention.

[0019] Figure 2 A schematic diagram of a capacitor-inductor tuning unit that can integrate switches and filters;

[0020] Figure 3 This is a schematic diagram of the equivalent circuit of a single-pole double-throw switch in a fusion design.

[0021] Figure 4 The waveform simulation diagrams of insertion loss and isolation of a single-pole double-throw switch without a capacitor-inductor tuning unit are shown.

[0022] Figure 5 The waveform simulation diagrams of insertion loss and isolation of a single-pole double-throw switch using a capacitor-inductor tuned unit are shown.

[0023] Figure 6 The waveforms show a comparison of insertion loss and isolation for single-pole double-throw switches with and without a capacitor-inductor tuning unit.

[0024] Figure 7 Simulation waveforms of insertion loss and return loss for a switched filter bank without capacitor-inductor tuning units; Figure 7 In this diagram, 'a' represents the insertion loss waveform simulation. Figure 7 In the diagram, 'b' represents the simulated waveform of the return loss.

[0025] Figure 8 Simulation waveforms of insertion loss and return loss for a switched filter bank using a capacitor-inductor tuned unit; Figure 8 In this diagram, 'a' represents the insertion loss waveform simulation. Figure 8 In the diagram, 'b' represents the simulated waveform of the return loss.

[0026] Figure 9 The waveforms show a comparison of the insertion loss and return loss of the switching filter bank with and without the capacitor-inductor tuning unit. Figure 9 In this diagram, 'a' represents the insertion loss waveform simulation. Figure 9 In the diagram, 'b' represents the simulated waveform of the return loss.

[0027] The diagram shows: First filter 1, first capacitor-inductor tuning unit 1-1, second capacitor-inductor tuning unit 1-2, second filter 2, third capacitor-inductor tuning unit 2-1, and fourth capacitor-inductor tuning unit 2-2.

[0028] First microstrip line TL1, second microstrip line TL2, third microstrip line TL3, fourth microstrip line TL4, fifth microstrip line TL5, sixth microstrip line TL5, seventh microstrip line TL7, eighth microstrip line TL8, ninth microstrip line TL9, tenth microstrip line TL10;

[0029] First NMOS transistor M1, second NMOS transistor M2, third NMOS transistor M3, fourth NMOS transistor M4, fifth NMOS transistor M5, sixth NMOS transistor M6, seventh NMOS transistor M7, eighth NMOS transistor M8;

[0030] First resistor R1, second resistor R2, third resistor R3, fourth resistor R4, fifth resistor R5, sixth resistor R6, seventh resistor R7, eighth resistor R8, branch impedance Z offpath ;

[0031] First capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4, fifth capacitor C4, sixth capacitor C6, seventh capacitor C7, eighth capacitor C8; first turn-off capacitor C off1 Second turn-off capacitor C off2 ;

[0032] First inductor L1, second inductor L2, third inductor L3, fourth inductor L4;

[0033] First power supply Vg1, second power supply Vg2, third power supply Vg3, fourth power supply Vg4. Detailed Implementation

[0034] The invention will now be further described with reference to the accompanying drawings.

[0035] like Figure 1 The diagram illustrates a method for fusing monolithic integrated switches and filters for microwave and millimeter-wave applications. When fusing a single-pole double-throw switch with a bandpass filter, two parallel channels are connected between the signal input and signal output terminals. The first channel includes a series-connected switch circuit, a first capacitor-inductor tuning unit 1-1, a first filter 1, and a second capacitor-inductor tuning unit 1-2. The second channel includes a series-connected switch circuit, a third capacitor-inductor tuning unit 2-1, a second filter 2, and a fourth capacitor-inductor tuning unit 2-2. These four capacitor-inductor tuning units have identical structures.

[0036] The first channel specifically includes a ninth capacitor C9, a ninth microstrip line TL9, a first microstrip line TL1, a second microstrip line TL2, a first capacitor-inductor tuning unit 1-1, a first filter 1, a second capacitor-inductor tuning unit 1-2, a fifth microstrip line TL5, a sixth microstrip line TL6, a tenth microstrip line TL10, and a tenth capacitor C10, all connected in series. A first switching circuit is connected across the second microstrip line TL2, and a second switching circuit is connected across the fifth microstrip line TL5.

[0037] The second channel specifically includes the ninth capacitor C9, the ninth microstrip line TL9, the third microstrip line TL3, the fourth microstrip line TL4, the third capacitor-inductor tuning unit 2-1, the second filter 2, the fourth capacitor-inductor tuning unit 2-2, the seventh microstrip line TL7, the eighth microstrip line TL8, the tenth microstrip line TL10, and the tenth capacitor C10, which are connected in series in sequence. The third switching circuit is connected across the fourth microstrip line TL4, and the fourth switching circuit is connected across the seventh microstrip line TL7.

[0038] In the first switching circuit, the base of the first NMOS transistor M1 is connected to the first power supply Vg1 through the first resistor R1, and the collector of the first NMOS transistor M1 is connected to the front end of the second microstrip line TL2; the base of the second NMOS transistor M2 is connected to the first power supply Vg1 through the second resistor R2, and the collector of the second NMOS transistor M2 is connected to the rear end of the second microstrip line TL2.

[0039] The first, second, third, and fourth switch circuits have the same structure.

[0040] The first capacitor-inductor tuning unit 1-1 includes a first capacitor C1 and a first inductor L1 connected in series, and a second capacitor C2 is connected between the first capacitor C1 and the first inductor L1 to ground.

[0041] In the first capacitor-inductor tuning unit 1-1, the first capacitor C1 and the second capacitor C2 are plate capacitors with fixed capacitance values, and the first inductor L1 is a square inductor with a fixed inductance value. The plate capacitors C1 and C2 together with the square inductor L1 form a T-shaped first capacitor-inductor tuning unit 1-1.

[0042] The first capacitor C1 in the first capacitor-inductor tuning unit 1-1 is used for frequency compensation of the front-end switching circuit to broaden the frequency band range of the switch; the second capacitor C2 and the first inductor L1 introduce out-of-band transmission zeros for the subsequent bandpass filter, improving the out-of-band rejection capability of the bandpass filter; in the integrated design of the switch and filter, the parasitic capacitances present when the first NMOS transistor M1 and the second NMOS transistor M2 are turned off, along with the first capacitor-inductor tuning unit 1-1, are regarded as part of the bandpass filter and integrated into the bandpass filter to improve the insertion loss, return loss, and out-of-band rejection of the overall cascaded dual-channel switching filter bank.

[0043] The first capacitor-inductor tuning unit 1-1, the second capacitor-inductor tuning unit 1-2, the third capacitor-inductor tuning unit 2-1, and the fourth capacitor-inductor tuning unit 2-2 have the same structure.

[0044] When the first filter 1 and the second filter 2 are Chebyshev type bandpass filters, they are used to integrate single-pole double-throw switches and Chebyshev type bandpass filters. The four capacitor-inductor tuning units are respectively cascaded between two single-pole double-throw switches and two Chebyshev type bandpass filters.

[0045] like Figure 2 The figure shows the capacitor-inductor tuning unit. The first capacitor C1 in the capacitor-inductor tuning unit of this invention is integrated into the design of the front-stage single-pole double-throw switch circuit to perform frequency compensation on the front-stage single-pole double-throw switch circuit, thereby widening the switching bandwidth. The second capacitor C2 and the first inductor L1 introduce out-of-band transmission zeros for the subsequent bandpass filter, thereby improving the out-of-band rejection capability of the bandpass filter.

[0046] like Figure 3 The diagram shows the equivalent circuit of a single-pole double-throw switch in a fusion design. In this circuit, the first NMOS transistor M1 and the second NMOS transistor M2 are in the off state, equivalent to the first turn-off capacitor C. off1 Second turn-off capacitor C off2 The third NMOS transistor M3 and the fourth NMOS transistor M4 are in the on state, and are equivalent to the off-branch impedance Z of the rest of the branch. offpathThe first turn-off capacitor C off1 Second turn-off capacitor C off2 Together with the second microstrip line TL2, it forms a Π-type low-pass filter network. After adding the first capacitor C1, the frequency response is compensated, exhibiting a wideband bandpass response, thus completing the octave switching operation.

[0047] In the microwave and millimeter-wave frequency bands, single-pole double-throw switches, due to the parasitic capacitance present when the MOSFET is turned off, severely limit the frequency characteristics of the subsequent bandpass filter, thus affecting the performance of the entire switching filter bank. In the integrated design of switches and filters, the capacitor-inductor tuning unit and the parasitic capacitance present when the preceding MOSFET is turned off are regarded as part of the bandpass filter and integrated into the design of the bandpass filter, thereby improving the insertion loss, return loss and out-of-band rejection of the overall cascaded dual-channel switching filter bank.

[0048] The capacitor in the capacitor-inductor tuning unit is integrated into the design of a single-pole double-throw switch, thereby widening the bandwidth of the single-pole double-throw switch; the parasitic capacitance of the single-pole double-throw switch and the capacitor-inductor tuning unit are integrated into the design of a bandpass filter, thereby improving the insertion loss, return loss and out-of-band rejection of the overall cascaded dual-channel switching filter bank.

[0049] This invention, based on general microwave and millimeter-wave monolithic integrated switching filter banks, utilizes multiple capacitor and inductor tuning units to adjust the frequency response degradation caused by the cascading of switches and filters; performs frequency compensation on the switching circuit, thereby widening the switching bandwidth; and integrates the parasitic capacitance of the switching circuit and the capacitor and inductor tuning units into the design of the bandpass filter, thereby improving the insertion loss, return loss, and out-of-band rejection of the overall cascaded switching filter bank.

[0050] The following are the chip simulation results:

[0051] To verify the feasibility of the method of the present invention, a single-pole double-throw switch covering 18-45GHz, a Chebyshev bandpass filter covering 18-20GHz, and a Chebyshev bandpass filter covering 40-45GHz were designed using 0.1μm GaAs p-HEMT technology. Figure 4 The simulation waveforms show the insertion loss and isolation of a single-pole double-throw switch without a capacitor-inductor tuning unit. It can be seen that the range that satisfies the insertion loss of less than 1.5dB and the isolation of greater than 28dB is 19.5-37GHz. Figure 5 The simulation waveforms show the insertion loss and isolation of a single-pole double-throw switch using a capacitor-inductor tuned unit. It can be seen that the range that satisfies the insertion loss of less than 1.5dB and the isolation of greater than 28dB is 18-45GHz. Compared with the waveform without the capacitor-inductor tuned unit, the operating bandwidth of the switch is widened by 54%. Figure 7The simulation waveforms for the insertion loss and return loss of the switch filter bank without capacitor-inductor tuning units are shown. The insertion loss of the 18-20GHz path is less than 12dB and the return loss is less than 5dB. The insertion loss of the 40-45GHz path is less than 16dB and the return loss is less than 11dB. Figure 8 Simulated waveforms of insertion loss and return loss for the switched filter bank using capacitor-inductor tuned units were obtained. The insertion loss and return loss for the 18-20GHz path were both less than 10dB, and for the 40-45GHz path, the insertion loss was less than 10dB and the return loss was less than 11.5dB. Compared to the waveforms without capacitor-inductor tuned units, the 18-20GHz path showed a 2dB improvement in insertion loss, a 5dB improvement in return loss, a 7dB improvement in out-of-band low-frequency suppression, and a 19dB improvement in out-of-band high-frequency suppression. Similarly, the 40-45GHz path showed a 6dB improvement in insertion loss, a 0.5dB improvement in return loss, and a 19dB improvement in out-of-band low-frequency suppression. Therefore, the switch-filter fusion design method using capacitor-inductor tuned units broadened the switching bandwidth and improved the insertion loss, return loss, and out-of-band suppression of the overall cascaded dual-channel switched filter bank.

[0052] The single-pole double-throw switch and bandpass filter described above are only preferred embodiments of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and the invention can be extended to other types of modulator structures. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for fusing monolithic integrated switches and filters for microwave and millimeter-wave applications, characterized in that: When this method is used to integrate a single-pole double-throw switch with a bandpass filter, two parallel channels are connected between the signal input and signal output terminals. The first channel includes a series-connected switch circuit, a first capacitor-inductor tuning unit (1-1), a first filter (1), and a second capacitor-inductor tuning unit (1-2). The second channel includes a series-connected switch circuit, a third capacitor-inductor tuning unit (2-1), a second filter (2), and a fourth capacitor-inductor tuning unit (2-2). The four capacitor-inductor tuning units have the same structure.

2. The method for fusing monolithic integrated switches and filters for microwave and millimeter-wave applications according to claim 1, characterized in that: The first channel specifically includes a ninth capacitor (C9), a ninth microstrip line (TL9), a first microstrip line (TL1), a second microstrip line (TL2), a first capacitor-inductor tuning unit (1-1), a first filter (1), a second capacitor-inductor tuning unit (1-2), a fifth microstrip line (TL5), a sixth microstrip line (TL6), a tenth microstrip line (TL10), and a tenth capacitor (C10) connected in series. A first switching circuit is connected across the second microstrip line (TL2), and a second switching circuit is connected across the fifth microstrip line (TL5).

3. The method for fusing monolithic integrated switches and filters for microwave and millimeter-wave applications according to claim 1, characterized in that: The second channel specifically includes the ninth capacitor (C9), the ninth microstrip line (TL9), the third microstrip line (TL3), the fourth microstrip line (TL4), the third capacitor-inductor tuning unit (2-1), the second filter (2), the fourth capacitor-inductor tuning unit (2-2), the seventh microstrip line (TL7), the eighth microstrip line (TL8), the tenth microstrip line (TL10), and the tenth capacitor (C10) connected in series. The third switching circuit is connected to both ends of the fourth microstrip line (TL4), and the fourth switching circuit is connected to both ends of the seventh microstrip line (TL7).

4. The method for fusing monolithic integrated switches and filters for microwave and millimeter-wave applications according to claim 2, characterized in that: In the first switching circuit, the base of the first NMOS transistor (M1) is connected to the first power supply (Vg1) through the first resistor (R1), and the collector of the first NMOS transistor (M1) is connected to the front end of the second microstrip line (TL2); the base of the second NMOS transistor (M2) is connected to the first power supply (Vg1) through the second resistor (R2), and the collector of the second NMOS transistor (M2) is connected to the rear end of the second microstrip line (TL2).

5. The method for fusing monolithic integrated switches and filters for microwave and millimeter-wave applications according to claim 2, 3, or 4, characterized in that: The first, second, third, and fourth switch circuits have the same structure.

6. The method for fusing monolithic integrated switches and filters for microwave and millimeter-wave applications according to claim 1 or 2, characterized in that: The first capacitor-inductor tuning unit (1-1) includes a first capacitor (C1) and a first inductor (L1) connected in series, and a second capacitor (C2) is connected between the first capacitor (C1) and the first inductor (L1) to ground.

7. The method for fusing monolithic integrated switches and filters for microwave and millimeter-wave applications according to claim 6, characterized in that: In the first capacitor-inductor tuning unit (1-1), the first capacitor (C1) and the second capacitor (C2) are plate capacitors with fixed capacitance values, and the first inductor (L1) is a square inductor with fixed inductance values. The plate capacitors (C1) and (C2) together with the square inductor (L1) form a T-shaped first capacitor-inductor tuning unit (1-1).

8. The method for fusing monolithic integrated switches and filters for microwave and millimeter-wave applications according to claim 1 or 4, characterized in that: The first capacitor (C1) in the first capacitor-inductor tuning unit (1-1) is used for frequency compensation of the front-end switching circuit to broaden the frequency band of the switch; the second capacitor (C2) and the first inductor (L1) introduce out-of-band transmission zeros for the subsequent bandpass filter to improve the out-of-band rejection capability of the bandpass filter; in the integrated design of the switch and filter, the parasitic capacitances of the first NMOS transistor (M1) and the second NMOS transistor (M2) when they are turned off, along with the first capacitor-inductor tuning unit (1-1), are regarded as part of the bandpass filter and integrated into the bandpass filter to improve the insertion loss, return loss and out-of-band rejection of the overall cascaded dual-channel switching filter group.

9. The method for fusing monolithic integrated switches and filters for microwave and millimeter-wave applications according to claim 1, 2, or 3, characterized in that: The first capacitor-inductor tuning unit (1-1), the second capacitor-inductor tuning unit (1-2), the third capacitor-inductor tuning unit (2-1), and the fourth capacitor-inductor tuning unit (2-2) have the same structure.

10. The method for fusing monolithic integrated switches and filters for microwave and millimeter-wave applications according to claim 1, 2, or 3, characterized in that: When the first filter (1) and the second filter (2) are Chebyshev type bandpass filters, they are used to integrate single-pole double-throw switches and Chebyshev type bandpass filters. The four capacitor-inductor tuning units are respectively cascaded between two single-pole double-throw switches and two Chebyshev type bandpass filters.

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