X-band radio frequency power detector based on positive and negative thermistors

Abstract

The invention discloses an X-band radio frequency power detector based on positive and negative thermistors. Comprising a Wheatstone bridge structure formed by a radio frequency signal input port P1, a direct current signal input port P2, a signal output port Vout, a direct current voltage supply VDD, two radio frequency power absorber resistors RT1 and RT2, two positive temperature coefficient thermistors RP1 and RP2 and two negative temperature coefficient thermistors RN1 and RN2. Compared with a traditional radio frequency power detector, the radio frequency power detector is compatible with a standard CMOS (complementary metal oxide semiconductor) process and does not need a subsequent micromachining step, so that the radio frequency power detector has the advantages of low cost, easiness in monolithic integration and the like. In addition, by adopting a deep N-well adaptive design, the sensitivity and linearity of the device are effectively improved, and the detector is suitable for power detection application in X-band and other radio frequency microwave systems.

Description

Technical Field

[0001] This invention relates to the field of integrated radio frequency circuit technology, and in particular to an X-band radio frequency power detector based on positive and negative thermistors. Background Technology

[0002] Radio frequency (RF) power measurement is a key technology module in applications such as radar systems, millimeter-wave wireless systems, electronic countermeasures, automatic level control, and RFID. Schemes for RF power detection mainly include thermoelectric detectors based on thermocouples, rectifier detectors based on Schottky diodes, MOS transistor detectors, and capacitive detectors based on microelectromechanical systems (MEMS). Thermoelectric detectors rely on the Seebeck coefficient of the material, limiting their sensitivity; capacitive detectors require complex micromachining processes and are susceptible to parasitic capacitance and noise; diode detectors suffer from nonlinearity and temperature sensitivity. While existing thermistor-based RF MEMS power detectors offer high sensitivity, they typically require post-processing to form micromechanical thin-film structures, increasing process complexity and cost. To address the problems of the aforementioned RF power detection technologies, this invention designs an X-band RF power detector based on positive and negative thermistors using standard CMOS technology. Summary of the Invention

[0003] This invention proposes an integrated radio frequency power detector with compact structure, high linearity, X-band capability, and small size, aiming to effectively address the technical challenges faced by existing radio frequency power measurement technologies, such as low integration, insufficient linearity, and large size, in order to meet the requirements of the increasing trend of radio frequency transceiver systems towards higher integration.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] An X-band radio frequency power detector based on positive and negative thermistors includes an radio frequency signal input port P1 and a DC signal input port P2. 2、 Signal output port V out DC voltage supply VDD, two RF power absorber resistors R T1 and R T2 Two positive temperature coefficient thermistors R P1 and R P2 And two negative temperature coefficient thermistors R N1 and R N2 The Wheatstone bridge structure. The incident radio frequency power passes through the radio frequency power absorber resistor R. T1 and R T2 The heat is converted to Joule heating, which is then conducted through the substrate to the two positive temperature coefficient thermistors R. P1 and R P2As the temperature rises, a DC voltage is applied to the input terminal P2, which is then applied through the RF power absorber resistor R. T1 and R T2 Make the thermistor R P1 and R P2 The change occurs, and the RF power is then measured by the output of the balanced Wheatstone bridge structure.

[0006] The advantages of adopting the above scheme are: This invention is fully compatible with standard CMOS process flow, requires no subsequent micromachining or special materials, and is easy to integrate with existing RF integrated circuits on a single chip, significantly reducing manufacturing costs. The use of a balanced Wheatstone bridge structure incorporating positive and negative temperature coefficient thermistors efficiently converts temperature changes into differential voltage output, providing high sensitivity and inherently good RF-DC linearity. The integrated N-type well region effectively suppresses heat loss and noise, and combined with a low-loss coplanar waveguide design, achieves excellent impedance matching in the 8-12 GHz frequency band. The entire chip area is small (0.26 × 0.4 mm²), suitable for high-density integration.

[0007] Preferably, the radio frequency power detector comprises the following:

[0008] P-type Si substrate S1, metal layer Al, metal layer via VI, contact via CT, pad oxide layer, and poly layer insulating layer, wherein the substrate, pad oxide layer, poly layer and metal layer are arranged sequentially from bottom to top.

[0009] Preferably, the signal line S of the first coplanar waveguide structure is connected to the RF power absorber resistor R. T1 and R T2 The first end is electrically connected through a via VIA, and the ground line G of the first coplanar waveguide structure is connected to the RF power absorber resistor R. T1 and R T2 The second end is electrically connected via a through-hole VIAs, and the positive temperature coefficient thermistor R... P1 With negative temperature coefficient thermistor R N2 Series electrical connection, positive temperature coefficient thermistor R P2 With negative temperature coefficient thermistor R N1 Series electrical connection.

[0010] Preferably, four thermistors R P1、 R N1 R P2 With R N2 The connection method is as follows:

[0011] Thermistor bridge arm R P1 The first end is connected to the thermistor bridge arm R N2 The second terminal is electrically connected;

[0012] Thermistor bridge arm R P1 The second end is connected to the thermistor bridge arm R N1 First terminal electrical connection;

[0013] Thermistor bridge arm R N1 The second end is connected to the thermistor bridge arm R P2 First terminal electrical connection;

[0014] Thermistor bridge arm R P2 The second end is connected to the thermistor bridge arm R N2 The first terminal is electrically connected.

[0015] Preferably, the characteristic impedance of the first coplanar waveguide structure is 50Ω, and the resistor R of the terminal RF power absorber is... T1 =R T2 =100Ω, the initial resistance of the thermistor bridge arm satisfies R P1 =R P2 =R N1 =R N2 .

[0016] Preferably, the first coplanar waveguide structure is composed of metals M1, M2, M3, M4, M5 and M6 stacked vertically and electrically connected through array holes, and the signal line of the coplanar waveguide structure adopts the top layer of ultra-thick metal M6, and deep N-well regions are respectively provided below the four thermistor bridge arms and the two terminal RF power absorber resistors.

[0017] Preferably, the dimensions G / S / G of the first coplanar waveguide structure are 28um / 85um / 28um, the ground wire width is 120um, the lengths of the signal line and the ground line are 100um and 100um respectively, and the width and length of the four terminating resistors are 2um / 30um.

[0018] Preferably, the output of the Wheatstone bridge-type ultrawideband integrated RF power detector based on a thermistor is expressed as:

[0019] (1)

[0020] Among them, R P1 =R P2 =R N1 =R N2 Let ΔR be the initial resistance of the thermistor bridge arm. P1 ΔR P2 ΔR N1 and ΔR N2 This represents the change in resistance of the corresponding thermistor bridge arm.

[0021] Preferably, the resistance value of the thermistor bridge arm is expressed as:

[0022] (2)

[0023] Where α and β are the first and second temperature coefficients of the thermistor, respectively, and T and T0 are the temperature after the thermistor is increased and the room temperature, respectively.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention uses a coplanar waveguide structure combined with a balanced Wheatstone bridge based on positive and negative temperature coefficient thermistors to achieve accurate detection of radio frequency power. Through the adaptive design of the deep N-well, the corresponding sensitivities at 8 GHz, 10 GHz and 12 GHz are 0.169 mV / mW, 0.163 mV / mW and 0.154 mV / mW respectively, effectively improving the sensitivity and linearity of the device. Attached Figure Description

[0026] Figure 1 This is a schematic diagram and equivalent circuit model of the X-band radio frequency power detector based on positive and negative thermistors of the present invention;

[0027] Figure 2 This is the equivalent circuit model of the X-band radio frequency power detector based on positive and negative thermistors in this invention;

[0028] Figure 3 This is a cross-sectional view of the hierarchical structure of the X-band radio frequency power detector based on positive and negative thermistors of the present invention.

[0029] Figure 4 The figure shows the simulation results of the return loss of the X-band radio frequency power detector based on positive and negative thermistors of this invention.

[0030] Figure 5 This is a graph showing the variation of the positive and negative temperature coefficient thermistors of this invention with temperature difference;

[0031] Figure 6 This is a simulation result diagram showing the temperature of the central axis of the terminal radio frequency power absorber as a function of input power in the X-band radio frequency power detector based on positive and negative thermistors of this invention.

[0032] Figure 7 This is a diagram showing the output results of the X-band radio frequency power detector based on positive and negative thermistors of this invention. Detailed Implementation

[0033] The technical solutions involved in the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. It should be noted that the described embodiments are only some implementations of the present invention, and not all of them. Based on the embodiments disclosed in this invention, any other embodiments that can be conceived by those skilled in the art without creative effort are within the protection scope of the claims of this invention.

[0034] Reference Appendix Figure 1 The X-band radio frequency power detector based on positive and negative thermistors includes an RF signal input port P1 and a DC signal input port P2. 2、 Signal output port V out DC voltage supply VDD, two RF power absorber resistors R T1 and R T2 Two positive temperature coefficient thermistors R P1 and R P2 And two negative temperature coefficient thermistors R N1 and R N2 The Wheatstone bridge structure.

[0035] In this embodiment, the signal line S of the first coplanar waveguide structure and the RF power absorber resistor R T1 and R T2 The first end is electrically connected through a via VIAs, and the ground line G of the first coplanar waveguide structure is connected to the resistor R of the terminal RF power absorber. T1 and R T2 The second end is electrically connected via a through-hole VIAs, and the positive temperature coefficient thermistor R... P1 With negative temperature coefficient thermistor R N2 Series electrical connection, positive temperature coefficient thermistor R P2 With negative temperature coefficient thermistor R N1 Series electrical connection.

[0036] The signal line S of the first coplanar waveguide structure and the resistor R of the terminal RF power absorber T1 and R T2 The first end is electrically connected through a via VIAs, and the ground line G of the first coplanar waveguide structure is connected to the resistor R of the terminal RF power absorber. T1 and R T2 The second end is electrically connected via a through-hole VIAs. Four thermistors R P1、 R N1 R P2 With R N2 Positive temperature coefficient thermistor R P1 With negative temperature coefficient thermistor R N2 Series electrical connection, positive temperature coefficient thermistor R P2 With negative temperature coefficient thermistor R N1 Series electrical connection.

[0037] More specifically, in this embodiment, the thermistor bridge arm R P1 The first end is connected to the thermistor bridge arm R N2 The second terminal is electrically connected; the thermistor bridge arm R P1 The second end is connected to the thermistor bridge arm R N1First terminal electrical connection; thermistor bridge arm R N1 The second end is connected to the thermistor bridge arm R P2 First terminal electrical connection; thermistor bridge arm R P2 The second end is connected to the thermistor bridge arm R N2 The first terminal is electrically connected. Simultaneously, a DC voltage is applied to the input terminal P2, which is absorbed by the terminating resistor R. T1 and R T2 Joule heating causes four thermistors R P1、 R N1 R P2 With R N2 The resistance value changes, and the radio frequency power is further measured through the output of the balanced Wheatstone bridge structure.

[0038] Reference Appendix Figure 3 The radio frequency power detector includes: a P-type Si substrate (S1), metal layers Al (1, 2, 3, 4, 5 and 6), metal layer vias VIA (7), contact holes CT (8), a pad oxide layer (9), a Poly layer (10), and insulating layers (11, 12, 13, 14, 15 and 16), wherein the substrate (1), the pad oxide layer (9), the Poly layer (10) and the metal layers (M1, M2, M3, M4, M5 and M6) are arranged sequentially from bottom to top.

[0039] In this embodiment, the characteristic impedance of the first coplanar waveguide structure is 50Ω, and the terminating RF absorption resistor R T1 =R T2 =100Ω, the initial resistance of the thermistor bridge arm satisfies R P1 =R P2 =R N1 =R N2 The ground plane of the first coplanar waveguide structure is formed by vertically stacking metals M1, M2, M3, M4, M5, and M6 and electrically connecting them through an array of apertures. Preferably, the first coplanar waveguide structure is formed by vertically stacking metals M1, M2, M3, M4, M5, and M6 and electrically connecting them through an array of apertures. The signal line of the coplanar waveguide structure uses an ultra-thick top layer of metal M6. Deep N-well regions are respectively provided below the four thermistor bridge arms and the two terminating RF power absorber resistors. The dimensions G / S / G of the first and second coplanar waveguide structures are 28um / 85um / 28um, the ground line width is 120um, the lengths of the signal line and the ground line are 100um and 100um respectively, and the width and length of the four terminating resistors are 2um / 30um.

[0040] In this embodiment, the output of the X-band radio frequency power detector based on positive and negative thermistors is expressed as:

[0041] (3)

[0042] Among them, R P1 =R P2 =R N1 =R N2 Let ΔR be the initial resistance of the thermistor bridge arm. P1 ΔR P2 ΔR N1 and ΔR N2 This represents the change in resistance of the corresponding thermistor bridge arm.

[0043] In this embodiment, the radio frequency power detector is completely symmetrical in both physical and circuit structure, therefore:

[0044] (4)

[0045] (5)

[0046] Using equations (3), (4), and (5), the output V of the X-band RF power detector based on positive and negative thermistors is obtained. out It can be simplified to:

[0047] (6)

[0048] High-frequency electromagnetic field simulation analysis was performed on an X-band RF power detector based on positive and negative thermistors, specifically including:

[0049] 1. Three-dimensional electromagnetic model construction: Step 1: Determine the geometric structure and material parameters; Step 2: Model the key structures, mainly including the coplanar waveguide structure, terminating resistor and Wheatstone bridge arm; Step 3: Set the air cavity and boundary conditions.

[0050] 2. Excitation port configuration: Step 1: Wavelength port type selection; Step 2: Wideband excitation settings;

[0051] 3. Mesh optimization: Step 1: Set the global maximum mesh size to 1 / 100 of the wavelength corresponding to the highest frequency; Step 2: Manually refine the mesh in key areas (terminating resistors and thermistors);

[0052] 4. Solving the full-wave electromagnetic field: Step 1: Select and set the solver; Step 2: Simulation execution and result post-processing to obtain the S-parameter characteristics of the device.

[0053] Appendix Figure 4 The figure shows the simulation results of the return loss of the X-band RF power detector based on positive and negative thermistors of the present invention. The results show that the input matching of the power detector in the embodiment reaches a better value and the input return loss is better than 20dB in the frequency range of 8-12GHz.

[0054] Appendix Figure 7 The image shows the output results of the X-band radio frequency power detector based on positive and negative thermistors according to this invention. The results indicate that the corresponding sensitivities at 8 GHz, 10 GHz, and 12 GHz are 0.169 mV / mW, 0.163 mV / mW, and 0.154 mV / mW, respectively. Compared with traditional thermocouple-based microwave power detectors, the sensitivity is significantly improved, and the output voltage exhibits an excellent linear relationship with the incident power.

[0055] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An X-band radio frequency power detector based on positive and negative thermistors, characterized in that, Includes RF signal input port P1 and DC signal input port P 2、 Signal output port V out DC voltage supply VDD, two RF power absorber resistors R T1 and R T2 Two positive temperature coefficient thermistors R P1 and R P2 And two negative temperature coefficient thermistors R N1 and R N2 The Wheatstone bridge structure. The incident radio frequency power passes through the radio frequency power absorber resistor R. T1 and R T2 The heat is converted to Joule heating, which is then conducted through the substrate to the two positive temperature coefficient thermistors R. P1 and R P2 As the temperature rises, a DC voltage is applied to the input terminal P2, which is then applied through the RF power absorber resistor R. T1 and R T2 Make the thermistor R P1 and R P2 The change occurs, and the RF power is then measured by the output of the balanced Wheatstone bridge structure.

2. The X-band radio frequency power detector based on positive and negative thermistors according to claim 1, characterized in that, The radio frequency power detector consists of the following components: P-type Si substrate S1, metal layers Al (1, 2, 3, 4, 5 and 6), metal layer via VIA (7), contact via CT (8), pad oxide layer (9), poly layer (10), and insulating layers (11, 12, 13, 14, 15 and 16), wherein the substrate (1), pad oxide layer (9), poly layer (10) and metal layers (1, 2, 3, 4, 5 and 6) are arranged sequentially from bottom to top.

3. The X-band radio frequency power detector based on positive and negative thermistors according to claim 1, characterized in that, The signal line S of the first coplanar waveguide structure and the resistor R of the RF power absorber T1 and R T2 The first end is electrically connected through a via VIA, and the ground line G of the first coplanar waveguide structure is connected to the RF power absorber resistor R. T1 and R T2 The second end is electrically connected via a through-hole VIAs, and the positive temperature coefficient thermistor R... P1 With negative temperature coefficient thermistor R N2 Series electrical connection, positive temperature coefficient thermistor R P2 With negative temperature coefficient thermistor R N1 Series electrical connection.

4. The X-band radio frequency power detector based on positive and negative thermistors according to claim 3, characterized in that, Four thermistors R P1、 R N1 R P2 With R N2 The connection method is as follows: Thermistor bridge arm R P1 The first end is connected to the thermistor bridge arm R N2 The second terminal is electrically connected; Thermistor bridge arm R P1 The second end is connected to the thermistor bridge arm R N1 First terminal electrical connection; Thermistor bridge arm R N1 The second end is connected to the thermistor bridge arm R P2 First terminal electrical connection; Thermistor bridge arm R P2 The second end is connected to the thermistor bridge arm R N2 The first terminal is electrically connected.

5. The X-band radio frequency power detector based on positive and negative thermistors according to claim 3, characterized in that, The characteristic impedance of the first coplanar waveguide structure is 50Ω, and the resistance of the terminating RF power absorber is R. T1 =R T2 =100Ω, the initial resistance of the thermistor bridge arm satisfies R P1 =R P2 =R N1 =R N2 .

6. The X-band radio frequency power detector based on positive and negative thermistors according to claim 3, characterized in that, The first coplanar waveguide structure consists of metals M1, M2, M3, M4, M5 and M6 stacked vertically and electrically connected through array holes. The signal lines of the coplanar waveguide structure use ultra-thick metal M6 on the top layer. Deep N-well regions are respectively set below the four thermistor bridge arms and the two terminal RF power absorber resistors.

7. The X-band radio frequency power detector based on positive and negative thermistors according to claim 3, characterized in that, The dimensions of the first coplanar waveguide structure are 28um / 85um / 28um (G / S / G), the ground wire width is 120um, the signal wire and ground wire lengths are 100um and 100um respectively, and the width and length of the four terminating resistors are 2um / 30um.

8. The X-band radio frequency power detector based on positive and negative thermistors according to claim 3, characterized in that, The output of the X-band RF power detector based on positive and negative thermistors is expressed as follows: （1） Among them, R P1 =R P2 =R N1 =R N2 Let ΔR be the initial resistance of the thermistor bridge arm. P1 ΔR P2 ΔR N1 and ΔR N2 This represents the change in resistance of the corresponding thermistor bridge arm.

9. An X-band radio frequency power detector based on positive and negative thermistors according to claim 3, characterized in that, The resistance value of the thermistor bridge arm is expressed as: Where α and β are the first and second temperature coefficients of the thermistor, respectively, and T and T0 are the temperature after the thermistor is increased and the room temperature, respectively.

10. The application of an X-band radio frequency power detector based on positive and negative thermistors according to any one of claims 1-9, characterized in that: This detector is used to detect radio frequency power.

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