Balanced broadband center frequency reconfigurable phase shifter

Abstract

The invention discloses a balanced broadband center frequency reconfigurable phase shifter which comprises a reference line and a main line, wherein the reference line and the main line have the same circuit topological structure and only correspond to parts with different physical sizes; the main line comprises two pairs of cascaded quarter-wavelength coupling microstrip lines, a stepped impedance microstrip line structure connected between the two pairs of coupling microstrip lines, and a frequency tuning unit connected to the stepped impedance microstrip line structure; the step impedance microstrip line structure connected between the two pairs of coupling microstrip lines is used for realizing broadband differential mode impedance matching; the frequency tuning unit comprises a variable capacitance diode, and by adjusting the bias voltage of the variable capacitance diode, continuous adjustment of the center frequency of the phase shifter can be achieved under the condition that differential mode impedance matching, the differential mode phase shifting characteristic and the common mode rejection performance are kept.

Description

TECHNICAL FIELD

[0001] The present application relates to a phase shifter, in particular to a balanced wideband center frequency reconfigurable phase shifter. BACKGROUND

[0002] Wireless communication systems are developing towards wideband, multi-band and multi-function integration, which puts forward higher requirements for the performance of terminal communication circuits. The system not only needs to maintain reliable operation in a wider frequency band and more frequency bands, but also must have the ability to resist environmental noise and suppress electromagnetic interference to ensure communication quality and transmission efficiency. As a key component in the field of radio frequency and microwave, the phase shifter is widely used in communication, radar and phased array systems. The balanced wideband phase shifter has become a research hotspot because it can simultaneously realize wideband differential mode phase shifting and wideband common mode suppression. At the same time, the center frequency reconfigurable phase shifter can dynamically adjust the operating frequency, which shows key value in multi-band adaptation and real-time spectrum regulation scenarios. Therefore, the balanced wideband center frequency reconfigurable phase shifter, which has the functions of wideband, center frequency reconfigurability and common mode suppression, is in line with the development direction of current wireless communication systems, and has important research significance and application prospect.

[0003] In recent years, various balanced wideband phase shifters have been proposed, and the implementation methods include coupled line loading stub, T-type multi-mode resonator and slot-based quasi-Schiffman structure. These designs have their own advantages, or in terms of operating bandwidth, or in terms of phase shift value range, or in terms of common mode suppression performance. However, these designs are fixed center frequency and cannot realize frequency reconfiguration. At present, the center frequency reconfigurable phase shifters reported mainly use the method based on vector sum, but are single-ended structures and do not have the function of common mode suppression. SUMMARY

[0004] The present application aims to provide a balanced wideband center frequency reconfigurable phase shifter, which has the functions of wideband, center frequency reconfigurability and common mode suppression.

[0005] The technical scheme of the present application is as follows: a balanced wideband center frequency reconfigurable phase shifter, comprising a reference line and a main line which have the same circuit topology and only have differences in corresponding physical dimensions; the main line comprises two pairs of cascaded quarter-wavelength coupled microstrip lines, a stepped impedance microstrip line structure connected between the two pairs of coupled microstrip lines, and a frequency tuning unit connected to the stepped impedance microstrip line structure; the stepped impedance microstrip line structure connected between the two pairs of coupled microstrip lines is used to realize wideband differential mode impedance matching; the frequency tuning unit comprises a varactor diode, and by adjusting the bias voltage of the varactor diode, the center frequency of the phase shifter can be continuously adjusted while maintaining the differential mode impedance matching, differential mode phase shift characteristics and common mode suppression performance.

[0006] Further, the main line structure is horizontally center-symmetrical; the two pairs of cascaded quarter-wavelength coupling microstrip lines are arranged horizontally in parallel and connected with the input microstrip lines at both ends respectively; and the four input microstrip lines are connected with the feed line through the DC blocking capacitors respectively. The main line further comprises two cross microstrip lines arranged in parallel in the vertical direction and connected between the two pairs of input microstrip lines corresponding to the two pairs of coupling microstrip lines at both ends.

[0007] Further, the stepped impedance microstrip line structure comprises two short microstrip lines and two center microstrip lines; one end of the two short microstrip lines is connected to the connection point of the two pairs of cascaded coupling microstrip lines respectively, and the other end is connected to one end of the two center microstrip lines respectively, and the other end of the two center microstrip lines is connected to each other. The main line further comprises a terminal resistor connected between the connection point of the two center microstrip lines and the ground.

[0008] Further, the main line comprises two frequency tuning units; each frequency tuning unit further comprises a tuning microstrip line, the cathode of the varactor diode is connected to one end of the tuning microstrip line, the anode is grounded, and the other end of the tuning microstrip line is connected to the connection point of the short microstrip line and the center microstrip line respectively. Further, the main line comprises two frequency tuning units; each frequency tuning unit further comprises a tuning microstrip line, the cathode of the varactor diode is connected to one end of the tuning microstrip line, the anode is grounded, and the other end of the tuning microstrip line is connected to the connection point of the short microstrip line and the center microstrip line respectively. V bias .

[0009] Further, the main line further comprises two common mode suppression units, each common mode suppression unit comprises an impedance microstrip line and a resistor, the resistor is connected between one end of the impedance microstrip line and the ground, and the other end of the impedance microstrip line is connected to the midpoint of the two cross microstrip lines respectively.

[0010] Further, the feed line has both signal transmission and phase delay functions; the phase difference between the feed line group in the reference line and the feed line group in the main line due to the difference in physical size constitutes the phase shift reference value of the phase shifter.

[0011] Further, the electrical length of the cross microstrip line is 175°.

[0012] Further, the electrical length of the short microstrip line is 10°, and the electrical length of the center microstrip line is 121°.

[0013] Further, the electrical length of the tuning microstrip line is 71°.

[0014] Further, the electrical length of the impedance microstrip lines of the two common-mode suppression units is 72° and 63.5°, respectively.

[0015] Beneficial effects: the existing balanced wideband phase shifter does not have the reconfigurable center frequency capability; and the phase shifter with the reconfigurable center frequency capability is a single-ended structure and does not have the common-mode suppression function. The present application realizes the wideband differential-mode impedance matching by loading the stepped impedance microstrip line in the middle of the two pairs of cascaded quarter-wavelength coupled microstrip lines; and by introducing the microstrip stub with the varactor diode connected to the terminal on the stepped impedance line, the center frequency of the phase shifter can be regulated without affecting the differential-mode impedance matching, differential-mode phase shift and common-mode suppression performance; thereby realizing the balanced wideband center frequency reconfigurable phase shifter with the functions of wideband, reconfigurable center frequency and common-mode suppression. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Fig. 1 is a structural diagram of the balanced wideband center frequency reconfigurable phase shifter; Figure 2 Fig. 2 is the differential-mode of the reference line; S Fig. 3 is the parameter full-wave simulation result; Figure 3 Fig. 4 is the common-mode of the reference line; S Fig. 5 is the parameter full-wave simulation result; Figure 4 Fig. 6 is the differential-mode of the 45° main line; S Fig. 7 is the parameter full-wave simulation result; Figure 5 Fig. 8 is the common-mode of the 45° main line; S Fig. 9 is the parameter full-wave simulation result; Figure 6 Fig. 10 is the differential-mode phase shift full-wave simulation result of the 45° main line; Figure 7 Fig. 11 is the differential-mode of the 90° main line; S Fig. 12 is the parameter full-wave simulation result; Figure 8 Fig. 13 is the common-mode of the 90° main line; S Fig. 14 is the parameter full-wave simulation result; Figure 9 Fig. 15 is the differential-mode phase shift full-wave simulation result of the 90° main line. DETAILED DESCRIPTION

[0017] The present application will be further explained in combination with the drawings.

[0018] A balanced wideband center frequency reconfigurable phase shifter, the circuit structure of the reference line and the main line of the phase shifter is the same.

[0019] Taking the main line circuit structure as an example, as shown in Figure 1As shown, the entire structure is symmetrical along the horizontal centerline, including feed lines 1-4, microstrip lines 5-8, quarter-wavelength coupling microstrip lines 9-12, microstrip lines 13 and 14 with an electrical length of 175°, microstrip lines 15 and 16 with an electrical length of 10°, microstrip lines 17 and 18 with electrical lengths of 72° and 63.5° respectively, microstrip lines 19 and 20 with an electrical length of 121°, microstrip lines 26 and 27 with an electrical length of 71°, grounding vias 21-25, a metal patch 28, and a resistor. R 1. R 2. R 3. Choke inductor L R Two varactor diodes C v1 Four DC blocking surface-mount capacitors C b .

[0020] Among them, the linewidth of microstrip lines 5-8 is the same as that of feed lines 1-4, and microstrip lines 5-8 are each connected by a DC blocking chip capacitor. C b Correspondingly connect feeders 1 to 4. One end of microstrip line 13 is connected to microstrip line 5, and the other end of microstrip line 13 is connected to microstrip line 6; one end of microstrip line 14 is connected to microstrip line 7, and the other end of microstrip line 14 is connected to microstrip line 8. One end of coupling microstrip line 9 and coupling microstrip line 10 are connected, and the other ends of coupling microstrip line 9 and coupling microstrip line 10 are connected to microstrip line 5 and microstrip line 7, respectively; one end of coupling microstrip line 11 and coupling microstrip line 12 are connected, and the other ends of coupling microstrip line 11 and coupling microstrip line 12 are connected to microstrip line 6 and microstrip line 8, respectively. One end of microstrip line 15 is connected to the connection point of coupling microstrip lines 9 and 10, and the other end of microstrip line 15 is connected to one end of microstrip line 19; one end of microstrip line 16 is connected to the connection point of coupling microstrip lines 11 and 12, and the other end of microstrip line 16 is connected to one end of microstrip line 20, and the other end of microstrip line 19 is connected to the other end of microstrip line 20. Two varactor diodes C v1 The cathodes are respectively connected to one end of microstrip lines 26 and 27, and two varactor diodes. C v1 The anodes of the microstrip lines are connected to grounding vias 24 and 25, respectively; the other end of microstrip line 26 is connected to the connection point of microstrip lines 15 and 19, and the other end of microstrip line 27 is connected to the connection point of microstrip lines 16 and 20. Resistor R 1 is connected between one end of the microstrip line 17 and the grounding via 22, resistor R 2 is connected between one end of microstrip line 18 and ground via 23; the other end of microstrip line 17 is connected to the midpoint of microstrip line 13, and the other end of microstrip line 18 is connected to the midpoint of microstrip line 14. Resistor R3 is connected at one end to the connection point of the microstrip lines 19, 20, and the resistance R 3 is connected at the other end to the ground via 21. The choke inductance L R 3 is connected at one end to the metal patch 28, and the choke inductance L R 3 is connected at the other end to the connection point of the microstrip lines 19, 20, and the metal patch 28 is used to connect the bias voltage V bias .

[0021] The reference line and the main line of the phase shifter differ in the physical dimensions of the corresponding parts. The feed lines 1-4 have a phase delay effect at the same time, i.e. the phase difference generated by the feed lines 1-4 in the reference line structure and the main line structure serves as the phase shift reference value of the phase shifter. The coupled microstrip lines 9-12 are mainly used to control the differential mode impedance matching and the common mode suppression bandwidth, and in combination with the microstrip lines 13-16, 19-20 and 26-27, the present application generates multiple differential mode transmission poles and multiple common mode transmission zeros to realize wideband differential mode impedance matching and wideband common mode suppression. In addition, the coupled microstrip lines 9-12 and the microstrip lines 19-20 and 26-27 jointly regulate the differential mode phase slope to realize wideband differential mode phase shift, and the microstrip lines 13-16 are used to fine-tune the differential mode phase shift bandwidth. By changing the bias voltage V bias of the two varactor diodes, the center frequency of the phase shifter can be regulated while the differential mode operating bandwidth remains basically unchanged, and the series connection of the microstrip lines 17 and 18 with the resistors and grounding can increase the common mode suppression bandwidth without affecting the differential mode operation.

[0022] The following gives an embodiment of the 45° and 90° phase shifters of the present application, whose circuit structure schematic diagram is shown in Figure 1 The embodiment phase shifter operates at 3.5 GHz, uses RO4003C substrate, whose dielectric constant is 3.38, loss angle is 0.0027, and thickness is 0.813 mm. The varactor diode uses SMV2201-040LF model, whose C v1 min=0.23 pF (20 V), C v1 max=2.1 pF (0 V). The simulation performances of the reference line, 45° and 90° main lines are shown in Figures 2 to 9 From Figures 2 to 9 it can be obtained that when the variable capacitance C v1 takes different values, the corresponding center frequency, 10-dB differential mode impedance matching bandwidth, in-band insertion loss, 10-dB common mode suppression bandwidth and phase shift bandwidth performances are shown in Table 1.

[0023] Simulation performance of balanced wideband center frequency reconfigurable phase shifter Capacitance C v1 (pF) Center frequency (GHz) Differential mode 10-dB impedance matching bandwidth (%) Minimum insertion loss (dB) 10-dB common mode rejection bandwidth (%) Phase shift error (°) Differential mode phase shift bandwidth (%) Reference line 1.2 / 0.7 / 0.38 3.3 / 3.5 / 3.9 83.4 / 85.4 / 82 1.4 / 1.87 / 2.13 >171 / / 45° 0.85 / 0.6 / 0.4 3.3 / 3.5 / 3.9 83.5 / 81.7 / 80 1.46 / 1.95 / 1.89 >171 ±2.57 / ±2.57 / ±2.55 80.8 / 80 / 82.6 90° 0.95 / 0.7 / 0.46 3.3 / 3.5 / 3.9 80.4 / 78.5 / 82.4 1.39 / 1.73 / 1.6 >171 ±5.56 / ±5.57 / ±5.58 78.8 / 80 / 78.5 From table 1, for reference line, when C v1 From 1.2pF to 0.38pF, the center frequency adjustable range is 3.3GHz-3.9GHz (18%); for 45° main line, when C v1 From 0.85pF to 0.4pF, the center frequency adjustable range is 3.3GHz-3.9GHz (17.1%); for 90° main line, when C v1 From 0.95pF to 0.46pF, the center frequency adjustable range is 3.3GHz-3.9GHz (17.7%). In the center frequency change process, the 10-dB differential mode impedance matching bandwidth of reference line, 45° and 90° main line is basically consistent, and the common mode suppression bandwidth of reference line, 45° and 90° main line can completely cover the corresponding differential mode working bandwidth.

[0024] Compared with the existing balanced wideband phase shifter, the application has the advantage of center frequency reconfigurable. Compared with the center frequency reconfigurable phase shifter, the application has the advantage of common mode suppression.

[0025] The above only is the preferred embodiment of the application, it should be pointed out, for ordinary skilled in the art, on the premise of not departing from the principles of the application, can also make a number of improvements and refinements, these improvements and refinements also should be regarded as the protection scope of the application.

Claims

1. A balanced broadband center frequency reconfigurable phase shifter, characterized in that, It includes a reference line and a main line with the same circuit topology but different physical dimensions in some parts; the main line includes two pairs of cascaded quarter-wavelength coupled microstrip lines, a step impedance microstrip line structure connected between the two pairs of coupled microstrip lines, and a frequency tuning unit connected to the step impedance microstrip line structure. The stepped impedance microstrip line structure connected between two pairs of coupled microstrip lines is used to achieve broadband differential-mode impedance matching; the frequency tuning unit includes a varactor diode, and by adjusting the bias voltage of the varactor diode, the center frequency of the phase shifter can be continuously adjusted while maintaining differential-mode impedance matching, differential-mode phase shift characteristics and common-mode rejection performance.

2. The balanced broadband center frequency reconfigurable phase shifter according to claim 1, characterized in that, The structure of the main line is symmetrical along the horizontal centerline; the two pairs of cascaded quarter-wavelength coupled microstrip lines are arranged parallel to each other in the horizontal direction, and their two ends are respectively connected to the input microstrip lines; the four input microstrip lines are respectively connected to the feed line through DC blocking capacitors; The main line also includes two bridging microstrip lines arranged parallel to each other in the vertical direction, which are respectively connected between the two pairs of input microstrip lines at both ends of the two cascaded coupling microstrip lines.

3. The balanced broadband center frequency reconfigurable phase shifter according to claim 2, characterized in that, The stepped impedance microstrip line structure includes two short microstrip lines and two central microstrip lines; one end of each of the two short microstrip lines is connected to the connection point of the two cascaded coupled microstrip lines, and the other end is connected to one end of each of the two central microstrip lines, and the other ends of the two central microstrip lines are connected to each other. The main line also includes a terminating resistor connected between the junction of the two central microstrip lines and ground.

4. The balanced broadband center frequency reconfigurable phase shifter according to claim 3, characterized in that, The main line includes two frequency tuning units; each frequency tuning unit further includes a tuning microstrip line, the cathode of the varactor diode is connected to one end of the tuning microstrip line, the anode is grounded, and the other end of the tuning microstrip line is connected to the connection point of the short microstrip line and the center microstrip line respectively. It also includes a bias circuit; the bias circuit includes a metal patch and a choke inductor, one end of which is connected to the metal patch, and the other end is connected to the junction of the two center microstrip lines; the metal patch is used to apply a bias voltage. V bias .

5. The balanced broadband center frequency reconfigurable phase shifter according to claim 4, characterized in that, The main line also includes two common-mode suppression units. Each common-mode suppression unit includes an impedance microstrip line and a resistor. The resistor is connected between one end of the impedance microstrip line and ground, and the other end of the impedance microstrip line is connected to the midpoint of the two bridging microstrip lines respectively.

6. The balanced broadband center frequency reconfigurable phase shifter according to any one of claims 2-5, characterized in that, The feed line has both signal transmission and phase delay functions; the phase difference between the feed line group in the reference line and the feed line group in the main line due to the difference in physical size constitutes the phase shift reference value of the phase shifter.

7. The balanced broadband center frequency reconfigurable phase shifter according to any one of claims 2-5, characterized in that, The electrical length of the bridging microstrip line is 175°.

8. The balanced broadband center frequency reconfigurable phase shifter according to any one of claims 3-5, characterized in that, The short microstrip line has an electrical length of 10°, and the central microstrip line has an electrical length of 121°.

9. The balanced broadband center frequency reconfigurable phase shifter according to claim 4 or 5, characterized in that, The electrical length of the tuned microstrip line is 71°.

10. The balanced broadband center frequency reconfigurable phase shifter according to claim 5, characterized in that, The impedance microstrip lines of the two common-mode suppression units have electrical lengths of 72° and 63.5°, respectively.

Images