Tunable Capacitors Research Articles

Multiband Frequency Tuneable Antennas for Selection Combining Strategy in White Space Applications

This article presents a reconfigurable antenna using digitally tuneable capacitors (DTCs). Mounted on a 120 × 200 mm2 ground plane, the radiating element has very compact dimensions of 0.06λg × 0.016λg × 0.0016λg (with λg being the wavelength at 585 MHz). The proposed structure could be operated in the white-space frequency band from 470 to 700 MHz. The antenna system is composed of two radiated elements that are placed at the corner of the board. The active components were soldered onto the antennas and controlled by an embedded microcontroller via the I2C interface. Antenna impedances were simulated and evaluated by measurement with an impedance-matching bandwidth of 39.32% (470–700 MHz) for an S11 less than −6 dB. Furthermore, the numerical results show a realized maximal gain ranging from −2.2 dBi at 470 MHz to 1.87 dBi at 700 MHz. Lastly, the diversity gains based on the radiation pattern of two resonators were calculated. The results show envelope correlation coefficient (ECC) values lower than 0.5 for the different configurations.

A 24 GHz CMOS Direct-Conversion RF Receiver with I/Q Mismatch Calibration for Radar Sensor Applications.

A 24 GHz millimeter-wave direct-conversion radio-frequency (RF) receiver with wide-range and precise I/Q mismatch calibration is designed in 65 nm CMOS technology for radar sensor applications. The CMOS RF receiver is based on a quadrature direct-conversion architecture. Analytic relations are derived to clearly exhibit the individual contributions of the I/Q amplitude and phase mismatches to the image-rejection ratio (IRR) degradation, which provides a useful design guide for determining the range and resolution of the I/Q mismatch calibration circuit. The designed CMOS RF receiver comprises a low-noise amplifier, quadrature down-conversion mixer, baseband amplifier, and quadrature LO generator. Controlling the individual gate bias voltages of the switching FETs in the down-conversion mixer having a resistive load is found to induce significant changes at the amplitude and phase of the output signal. In the calibration process, the mixer gate bias tuning is first performed for the amplitude mismatch calibration, and the remaining phase mismatch is then calibrated out by the varactor capacitance tuning at the LO buffer's LC load. Implemented in 65 nm CMOS process, the RF receiver achieves 31.5 dB power gain, -35.2 dBm input-referred 1 dB compression power, and 4.8-7.1 dB noise figure across 22.5-26.1 GHz band, while dissipating 106.2 mA from a 1.2 V supply. The effectiveness of the proposed I/Q mismatch calibration is successfully verified by observing that the amplitude and phase mismatches are improved from 1.0-1.5 dB to 0.02-0.19 dB, and from 10.8-23.8 to 1.1-3.2 degrees, respectively.

FEM simulation‐based development of a new tunable non‐magnetic RF high voltage capacitor for the new generation of MRI

Using Radio Frequency (RF) waves, magnetic resonance imaging (MRI) systems can make detailed images of human organs for accurate diagnostic processes and disease detection. The overhaul of certain electronic components has become necessary to keep up with the progress of MRI systems. Among the components responsible for image quality, the adjustable non-magnetic capacitors, also called trimmers, are of great importance. The purpose of this paper is to suggest a new design of a trimmer using non-magnetic materials, able to hold a high voltage ( >3 kV) and reach a resonance frequency above 100 MHz. Constructional analysis performed on existing commercial trimmers, combined with the electrical Finite Element Method, were carried out to propose a prototype matching the desired specifications. A dielectric shield surrounding the electrodes was sized to ensure voltage withstand. Moreover, the rotor and the worm-and-gear set were joined together to combat the vibrations generated by the MRI system. The present study includes the modelling step of the component by numerical simulation, the manufacturing, the electrical performance characterization, and the mechanical solution for tuning capacitance. The final prototype combines electrical performance corresponding to the required specifications in particular a high breakdown voltage (39.7 kV) and a resonance frequency (130 MHz).

Study on the Effect of Non-Symmetrical Current Distribution Controlled by Capacitor Placement in Radio-Frequency Coils for 7T MRI.

In this paper, we present a study on the effects of varying the position of a single tuning capacitor in a circular loop coil as a mechanism to control and produce non-symmetric current distribution, such that could be used for magnetic resonance imaging (MRI) operating at ultra-high frequency (UHF). This study aims to demonstrate that the position of the tuning capacitor of a circular loop could improve the coupling between adjacent coils, used to optimize transmission field uniformity or intensity, improve signal-to-noise ratio (SNR) or specific absorption rate (SAR). A typical loop coil used in MRI consists of symmetrically distributed capacitors along the coil; this design is able to produce uniform current distributions inside the coil. However, in UHF conditions, the magnetic flux density (|B1+|) field produced by this setup may exhibit field distortion, requiring a method of controlling the field distribution and improving the field intensity of the circular loop coil. The control mechanism investigated in this study is based on the position of the tuning capacitor in the circular coil, the capacitor position was varied from 15° to 345°, in steps of 15°. We performed electromagnetic (EM) simulations, fabricated the coils, and performed MRI experiments at 7T, with each of the coils with capacitor position from 15° to 345° to determine the effects on field intensity, coupling between adjacent coils, SAR, and applications for field uniformity optimization. For the case of free space, a coil with capacitor position at 15° showed higher field intensity compared to the reference coil; while an improved decoupling was achieved when a coil had the capacitor placed at 180° and the other coil at 90°; in a similar matter, we discuss the results for SAR, field uniformity and an application with an array coil for the spinal cord.

Integrated dual‐band multiple‐input multiple‐output antenna module using higher mode control for 5G applications

This study presents a self-decoupled and highly integrated multiple-input multiple-output (MIMO) antenna pair for the 3.5 GHz (3.4–3.6 GHz) and 5 GHz (4.8–5 GHz) frequency bands, where a loop-type antenna and a dipole-type antenna are assembled into the front and backside of a compact modular board. A tuning inductor and a tuning capacitor are employed in the loop-type antenna and the dipole-type antenna, respectively, for higher mode resonance control, such that the dominant mode and higher mode of each antenna element are excited to achieve dual-band operation. Herein, the dominant modes of the loop-type antenna and the dipole-type antenna are orthogonal to each other, contributing to the self-decoupling effect in the lower band. Otherwise, the modal orthogonality of the higher modes of the two antennas is responsible for the high-isolated performance of the higher band. In this way, the proposed dual-band MIMO antenna module obtains a high spatial utilization ratio, even though they are disposed of in the same volume. The MIMO antenna module can produce impedance bandwidths above 200 MHz at both frequency bands, and the isolation within the lower and higher bands is above 16.5 and 13.5 dB, respectively. Additionally, an 8 × 8 MIMO antenna array is further constructed and measured. In measurement, the total efficiencies are higher than 60%, and the envelope correlation coefficient values are all below 0.1. Therefore, it is demonstrated that the proposed technique can be promisingly applied in large-scale MIMO antenna systems for current and future terminal devices, having advantages in multiband operation, high integration, and inherent isolation.

Double-crossed radiofrequency coil with improved uniformity for rodent MRI at 7 T

A transceiver volume coil for High Field Magnetic Resonance Imaging was developed based on Temnikov’s NMR probe coil. The critical advantage of this design is that requires only one trimmer capacitor for both tuning and matching. Electromagnetic simulations of our coil were compared to a four-rung birdcage coil to evaluate their performances. A transceiver coil prototype, called the double-cross coil and a birdcage coil were built to compare and contrast their feasibility. Both coil prototypes were operated in the linear mode. Experimental quality factors were Qu/Ql=101/45 for the double-cross coil and Qu/Ql=105/43 for the birdcage coil. Phantom images were acquired to test the viability of each coil for high field magnetic resonance imaging applications. The signal-to-noise ratios, noise factors and uniformity values were also calculated: 85.26/0.74/44.48 for the double-cross coil and 76.54/1.9/65.65 for the birdcage coil. These volume coils showed similar performance, but the double-cross coil has better uniformity and a slightly lower noise figure than the birdcage coil. A remarkable agreement of experimental and simulated B1 was obtained for the double-cross coil. These experimental and numerical results demonstrate the feasibility of the double-cross volume coil with better uniformity for rodent magnetic resonance imaging at 7 T.

A Resonant Cavity Based on Capacitively Loaded Coaxial Structure for Overhauser Magnetic Sensors

The RF excitation coil is an important component of the Overhauser magnetic sensor, which determines whether the dynamic nucleation polarization of the free radical solution can be carried out smoothly. A capacitance-loaded resonant cavity structure is proposed as the RF excitation of the Overhauser magnetic sensor. The structure and equivalent circuit of the capacitance-loaded coaxial resonant cavity are analyzed and improved on the conventional structure, and the resonant frequency is verified to be consistent with the excitation frequency of the free radical solution by modeling and simulation using COMSOL software. The resonant cavity solid was fabricated, and the cavity was tested by using a vector network analyzer. The results show that the initial resonance point of the homemade resonant cavity is 60.55MHz, and the frequency point can be adjusted to 60.7MHz by adjusting the loading capacitor and tuning capacitor; the resonant cavity return loss S11 is about -19dB, and the quality factor Q value is about 506.

An Active EMI Cancellation Technique Achieving a 25-dB Reduction in Conducted EMI of LIN Drivers

Robustness to electromagnetic interference (EMI) is one of the primary design aspects of state of the art automotive ICs like System Basis Chips (SBCs) which provide a wide range of analog, power regulation and digital functions on the same die. One of the primary sources of conducted EMI on the Local Interconnect Network (LIN) driver output is an integrated switching DC-DC regulator noise coupling through the parasitic substrate capacitance of the SBC. In this paper an adaptive active EMI cancellation technique to cancel the switching noise of the DC-DC regulator on the LIN driver output to ensure electromagnetic compatibility (EMC) is presented. The proposed active EMI cancellation circuit synthesizes a phase synchronized cancellation pulse which is then injected onto the LIN driver output using an on-chip tunable capacitor array to cancel the switching noise injected via substrate. The proposed EMI reduction technique can track and cancel substrate noise independent of process technology and device parasitics, input voltage, duty cycle and loading conditions of the DC-DC switching regulator. The EMI cancellation system is designed and fabricated on a 180nm Bipolar-CMOS-DMOS (BCD) process with an integrated power stage of a DC-DC buck regulator at a switching frequency of 2MHz along with an automotive LIN driver. The EMI cancellation circuit occupies an area of 0.7 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , which is less than 3% of the overall area in a standard SBC and consumes 12.5 mW of power and achieves 25 dB reduction of conducted EMI in the LIN driver output’s power spectrum at the switching frequency and its harmonics.

A high-Q superconducting toroidal medium frequency detection system with a capacitively adjustable frequency range >180 kHz.

We describe a newly developed polytetrafluoroethylene/copper capacitor driven by a cryogenic piezoelectric slip-stick stage and demonstrate with the chosen layout cryogenic capacitance tuning of ≈60 pF at ≈10 pF background capacitance. Connected to a highly sensitive superconducting toroidal LC circuit, we demonstrate tuning of the resonant frequency between 345 and 685kHz, at quality factors Q > 100 000. Connected to a cryogenic ultra low noise amplifier, a frequency tuning range between 520 and 710kHz is reached, while quality factors Q > 86 000 are achieved. This new device can be used as a versatile image current detector in high-precision Penning-trap experiments or as an LC-circuit-based haloscope detector to search for the conversion of axion-like dark matter to radio-frequency photons. This new development increases the sensitive detection bandwidth of our axion haloscope by a factor of ≈1000.

A low noise 5.12 GHz PLL ASIC in 55 nm for NICA multi purpose detector project

This paper presents the design and the test results of a low noise PLL ASIC for the optical data transmission system in NICA MPD project. In the proposed PLL, a novel charge pump circuit uses two feedback operational amplifiers to obtain low leakage current and reduce dynamic mismatch. A LC-VCO circuit combines the two-step capacitor tuning structure and the novel capacitor array unit to obtain a reasonable frequency range and an optimized Q factor performance. The PLL ASIC has been fabricated in a 55 nm CMOS process. The test results show that the PLL ASIC outputs the 5.12 GHz clock with a phase noise of −108 dBc/Hz at 1 MHz offset and a rms jitter of 880 fs. The PLL core consumes 22.2 mW from a 1.2 V power supply.

A Reconfigurable Balun-LNA and Tunable Filter With Frequency-Optimized Harmonic Rejection for Sub-GHz and 2.4 GHz IoT Receivers

A CMOS reconfigurable balun-LNA and tunable filter is proposed for sub-GHz and 2.4 GHz IoT applications. The core of the LNA gain stage is composed of two cascaded inverters for the single-to-differential conversion, and the additional inverter is placed in the feedback path for the implementation of the active feedback. In the sub-GHz band, it operates as an active feedback LNA by enabling all inverter stages. At the narrow 2.4 GHz band, it operates as an inductive source degenerated LNA (ISDLNA) with a minimum noise figure (NF) by disabling the inverter in the feedback path. In order to suppress the unwanted local oscillator (LO) harmonic mixing in the sub-GHz band and provide the frequency-optimized harmonic rejection ratio (HRR), a reconfigurable Sallen-Key (SK) filter-based <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4^{\mathbf {th}}$ </tex-math></inline-formula> -order tunable filter is proposed on the basis of the modified super source follower (SSF) with enhanced loop gain. It covers the entire VHF band with a smaller capacitance tuning ratio by switching the polarity of the output of the modified SSF. Compared to previous works, this work provides the largest tuning range from 50 MHz to 700 MHz without splitting individually optimized circuits corresponding to each frequency band and using no external board components. This is the first suggestion of a fully integrated SK filter-based tunable filter to cover VHF/UHF bands through a hardware re-configurability without increasing the tuning ratio of the switched capacitor array, while providing an optimum HRR performance for corresponding operating frequencies in conjunction with harmonic rejection mixer (HRM). In addition, it proposes a hardware efficient re-configurable balun-LNA to operate as a wideband feedback LNA at sub-GHz and a narrowband ISDLNA at 2.4 GHz without the use of external input matching circuits. In the measurement, the proposed front-end achieves an average power gain ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{S}_{{21}}$ </tex-math></inline-formula> ) of 25.9 dB, NF of < 4.25 dB, and in-band input-referred third-order intercept point (IIP3) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt;\!\!\!-12.8$ </tex-math></inline-formula> dBm over the tuning range from 50 MHz to 700MHz. The proposed tunable filter shows the frequency-optimized HRR from 10 dBc to 26 dBc over the tuning range while greatly reducing a silicon area. At 2.4 GHz band, it shows <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{S}_{{21}}$ </tex-math></inline-formula> of 14.7 dB, NF of 3.2 dB, and in-band IIP3 of −4.5 dBm. The die area of the proposed circuit, excluding I/O PADs and the measurement output buffer, is less than 2.0 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The power consumption of the front-end working at sub-GHz and 2.4 GHz bands is 33.6 mW and 5.1 mW respectively.

Single VDTA-based Lossless and Lossy Electronically Tunable Positive and Negative Grounded Capacitance Multipliers

Single VDTA-based Lossless and Lossy Electronically Tunable Positive and Negative Grounded Capacitance Multipliers

Unraveling the capacitive effect in the vacancy-heterostructure WTe2/MoTe2 for hydrogen evolution reaction by the grand canonical potential kinetics

Heterostructure shows superior catalytic performance since it inherits the catalytic properties of the components, and has the advantages of van der Waals interaction. Herein, we build a vacancy-van der Waals heterostructure with MoTe2 and WTe2 which forms a capacitor tuning performance, playing an important role in the energy barrier balance of the catalytic reaction. By using the grand canonical reaction kinetics (GCP-K) to explore the electrocatalytic, we predict the Tafel slope of the HER reaction is 81.31 mV/dec through changing applied potential.

Variable-area capacitors controlled by HfO2-based ferroelectric-gate field-effect transistors

We propose a three-terminal variable-area capacitor integrated with a ferroelectric-gate field-effect transistor (FeFET) and a paraelectric thin-film capacitor. Owing to the large charge controllability and nonvolatile memory function of the ferroelectric Hf0.86Ce0.14O2 (14% Ce-HfO2) gate insulator, the variable-area capacitors exhibited high capacitance tuning ratios of up to 184 with steep modulation to gate voltage swing (440 mV/decade), a capacitance-switching speed of less than 10 ms, and capacitance-memory-retention characteristics of up to 105 s. An FeFET with an indium tin oxide (ITO) channel and a ferroelectric 14% Ce-HfO2 gate insulator was fabricated as a switching FET via chemical solution deposition, followed by stacking a sputtered Al2O3 film as a variable capacitor. The fabricated FeFETs exhibited a high on-current of ∼0.15 A/mm, a large on/off current ratio of 107, a field-effect mobility of 15.6 cm2/V s, and a memory window of ∼5 V. The high on-current, i.e., low on-resistance (84 Ω), and the large on/off current ratio allow the ITO channel to act as a wiring that connects and disconnects two capacitors with different electrode areas; therefore, the proposed variable capacitor can achieve wide and steep modulation by ferroelectric gating. This study provides prospects for the future integration of passive and active components for advanced high-efficiency and miniaturized electronics such as power devices and communication equipment.

A Practical Guide to Estimating Coil Inductance for Magnetic Resonance Applications

Radiofrequency (RF) coils are employed to transmit and/or receive signals in Magnetic Resonance (MR) systems. The design of home-made, organ-specific RF coils with optimized homogeneity and/or Signal-to-Noise Ratio (SNR) can be a plus in many research projects. The first step requires accurate inductance calculation, this depending on the conductor’s geometry, to later define the tuning capacitor necessary to obtain the desired resonance frequency. To fulfil such a need it is very useful to perform a priori inductance estimation rather than relying on the time-consuming trial-and-error approach. This paper describes and compares two different procedures for coil inductance estimation to allow for a fast coil-prototyping process. The first method, based on calculations in the quasi-static approximation, permits an investigation on how the cross-sectional geometry of the RF coil conductors affects the total inductance and can be easily computed for a wide variety of coil geometries. The second approach uses a numerical full-wave method based on the Finite-Difference Time-Domain (FDTD) algorithm, and permits the simulation of RF coils with any complex geometry, including the case of multi-element phased array. Comparison with workbench measurements validates both the analytical and numerical results for RF coils operating within a wide field range (0.18–7 T).

Wide-range tunable Ba0.7Sr0.3TiO3 films capacitors on LiNbO3 substrates

Ba0.7Sr0.3TiO3 (BST) films on Y-cut LiNbO3 substrates are investigated to realize wide-range tunable BST capacitors. The performances of the BST films are improved by the optimal magnetron sputtering conditions. It is found that the permittivity tunability of the BST capacitor reaches 300% under an applied voltage of 5 V. Moreover, the film has a high dielectric constant 2700 under an applied voltage of 0 V, and the Q value of the BST capacitor exceeds 3000. The results demonstrate that the BST film on the LiNbO3 substrate has potential as a wide-range tunable capacitor for tunable surface acoustic wave filters.

Analysis and Design of the Tank Feedline in Millimeter-Wave VCOs

This article presents a detailed analysis of the impact of the tank feedline on tuning range (TR) and phase noise (PN) in millimeter-wave <i>LC</i> voltage-controlled oscillators (VCOs). A robust extended TR design, with low PN and small die area, is later proposed, analyzed, and experimentally validated. A new interconnect approach for the coarse tuning capacitor bank is used to significantly reduce the <i>LC</i> tank routing capacitance and resistance, thus improving the TR and PN of the VCO. As a proof of concept, a 26.8-GHz VCO with a 5-bit digitally switched-capacitor bank [capacitor digital-to-analog converter (C-DAC)] is implemented using a folded feedline routing structure in a digital 45-nm CMOS silicon-on-insulator (SOI) technology. Compared to a conventional layout structure, the proposed interconnect technique yields a wider TR and lower losses while significantly improving the linearity of the C-DAC. The fabricated VCO yields a TR of 33&#x0025;, covering the extended 5G frequency band with a sufficient margin from 22.4 to 31.2 GHz, with a minimum overlap of 40&#x0025;. Moreover, it achieves a PN of &#x2212;105.5 and &#x2212;97.2 dBc/Hz at a 1-MHz offset at the low and high bands, respectively, while dissipating 6 mW from a 1.0-V supply, corresponding to an average FOM_T of &#x2212;192.6 dBc/Hz.

Yb/WO3/Ga2S3/Au multifunctional electronic hybrid devices fabricated as tunneling diodes, MOSFETS, microwave resonators and 5G band pass/reject filters

Herein, Tungsten trioxide-gallium sulfide heterojunctions which are prepared by the thermal evaporation technique under a vacuum pressure of 10-5 mbar are employed as active media to fabricate a multifunctional device. The WO3/Ga2S3 (WG) heterojunctions which are deposited onto Yb substrates and top contacted with Au pads of areas of 1.5× 10 −2 cm2 displayed electronic hybrid device structure composed of two Schottky arms connected to a 𝑝𝑛 junction. The constructed Yb/WG/Au devices showed tunneling diode characteristics with current conduction dominated by thermionic emission and quantum mechanical tunneling. In additions, the capacitance-voltage characteristic curves indicated the formation of PMOS and NMOS under reverse and forwards biasing conditions demonstrating a metal oxide semiconductor fields effect (MOSFET) transistor characteristics. Moreover, the impedance spectroscopy tests on the devices have shown that the device can perform as tunable microwave resonator suitable for 5G technologies. The resonator showed frequency based capacitance tunability and displayed microwave band pass/reject filter characteristics. The microwave cutoff frequency of the Yb/WG/Au band filters reaches 9.65 GHz with voltage standing wave ratios of 1.06 and return loss factor of ~29 dB.

Design and analysis of 28 GHz CMOS low power LNA with 6.4 dB gain variability for 5G applications

AbstractA 28 GHz two stage low noise amplifier (LNA) is proposed with envelope detection technique for power reduction (21.62%) and tunable negative feedback capacitor for gain variation in 40 nm CMOS technology. The envelope detection circuit turn‐on the second half of the LNA by the RF signal input received at the first stage. The default gain is increased (31.53%) by the tunable negative feedback capacitor circuit of the LNA with the control voltage from 0 to 1 V. In addition, 6.22 GHz of bandwidth is achieved with the tunable gain from 20.3 dB to 26.7 dB. The first stage of the LNA is designed with the inductive source degeneration for the noise reduction, and the multiple‐gate topology is involved in the second stage to improve the linearity. The third‐order input intercept point and the noise figure of the LNA are −7 dBm and 2.86 dB, respectively. When the second stage is turned‐on and turned‐off the LNA consumes 7.4 mW and 5.8 mW of power, respectively, from the 1 V supply. The proposed LNA requires 0.19 mm2 of core area. The performance of the LNA under process corner variation and temperature variation are analyzed.

An E-Band SiGe High Efficiency, High Harmonic Suppression Amplifier Multiplier Chain With Wide Temperature Operating Range

This paper presents a monolithically integrated E-band amplifier multiplier chain (AMC) developed in 130 nm SiGe BiCMOS process. This E-band AMC is composed of a 25 GHz 1:1 power divider, two 25 GHz driver amplifiers (DA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1,2</sub> ), a 75 GHz passive frequency tripler, and a 75 GHz power amplifier (PA). By applying a bypass tuning capacitor based power enhancing technique in the single-ended DA and PA, the output power and power-added-efficiency (PAE) of the AMC have been effectively improved. Benefiting from the proposed passive tripler core with second harmonic suppression function, and the impedance matching network with frequency selection characteristics, the AMC presents better harmonic suppression performance compared with the conventional topology. The bias circuits with temperature compensation are applied to the DA and PA to ensure the performance of the AMC when the temperature changes. The AMC has a measured output power exceeding 0 dBm in the entire E-band frequency range with a peak output power of 10.9 dBm at 77 GHz, and exhibits a record PAE of 8.25 %. Within the 3 dB operating frequency range from 69 to 87 GHz, the rejection of fundamental and second harmonics are better than 33.5 dB. The AMC can work properly between −40°C and 125 °C with the proposed temperature compensation bias circuits.