Subharmonic Mixer Research Articles

A 0.68-THz Receiver With Third-Order Subharmonic Mixing in 65-nm CMOS

A 0.68-THz Receiver With Third-Order Subharmonic Mixing in 65-nm CMOS

A 335–407-GHz SiGe-Based Subharmonic Mixer Using a Fully Integrated LO Generation

A 335–407-GHz SiGe-Based Subharmonic Mixer Using a Fully Integrated LO Generation

All-optical high-order subharmonic mixer with a high signal-to-noise ratio and stable performance.

A photonics-based high-order subharmonic mixer, which enables a low-frequency LO source to be used for high-frequency RF signal frequency downconversion, is presented. It is based on an optically injected semiconductor laser, which is oscillated in the period-one state, sandwiched between two optical phase modulators. It has the advantages of a simple and compact structure, wide bandwidth, absence of electrical components, reconfigurable subharmonic mixing operation, stable output IF signal performance, high signal-to-noise ratio, infinite LO-to-RF port isolation, and high LO-to-IF port isolation. Furthermore, it is suitable for use in remote antenna applications. We set up a proof-of-concept experiment that demonstrates a reconfigurable second-, fourth-, sixth-, and eighth-order subharmonic mixing operation for different input RF signal frequencies and powers. The experimental results also demonstrate that the proposed structure exhibits a stable output IF signal performance, which overcomes the IF signal phase stability problem in the reported high-order subharmonic mixers.

Spacer layers’ thickness impact on the resonant-tunneling diode’s and frequency mixer’s operational parameters

The impact of spacer layers’ thickness on the resonant-tunneling diode’s (RTD) current-voltage characteristic and operational parameters of the RTD-based subharmonic mixer was studied during the described research using the software package developed by authors to simulate the RTD’s functional parameters while mixer’s parameters were simulated using existing microelectronic CAD. The research has revealed that the main impact on both RTD’s I-V characteristic’s shape and operational parameters of the studied subharmonic mixers is made by the emitter spacer layer’s thickness while the collector spacer’s thickness’ variation is insignificant in both cases. Such, it is shown that by varying the emitter spacer’s thickness from a single monolayer to twice its nominal value it’s possible to alter the RTD’s peak current from 0,28 to 1,92 of its nominal value. spacer layer’s thickness deviation of ±1 monolayer has a noticeable effect on the studied mixer’s operational parameters, especially on its dynamic range.

248 GHz Sub-Harmonic Mixer Last Transmitter With I/Q Imbalance and LO Feedthrough Calibration

248 GHz Sub-Harmonic Mixer Last Transmitter With I/Q Imbalance and LO Feedthrough Calibration

A 0.46–0.52-THz fully-differential quasi-monostatic FMCW radar transceiver in 90-nm SiGe BiCMOS

A 0.46–0.52-THz fully-differential quasi-monostatic frequency-modulated continuous-wave (FMCW) radar transceiver was designed in a 90-nm SiGe bipolar CMOS technology with fT/fmax\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extit{f}_{ \ extit{T}}/{f}_{\ ext{max}}$$\\end{document} of 300/480 GHz. The transceiver chip has an area of 2.84 mm2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext{mm}^{2}$$\\end{document}. A multiply-by-24 frequency multiplier chain is used to generate a 0.48-THz signal from a 20-GHz input signal. Two 0.48-THz push–push doublers are driven in quadrature for a differential output signal with a measured effective isotropic radiated power of up to -\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-$$\\end{document}8.8 dBm at the transmitter at 0.47 THz. A differential subharmonic receiver mixer with a stacked quad topology achieves a measured system conversion gain of 7 dB and a measured single-sideband noise figure of 25.2 dB at 0.471 THz. FMCW radar measurements are performed using an on-board frequency source of a credit card-sized demonstrator at a bandwidth of 60 GHz.

Efficiency Assessment of Traditional GaAs and Low-Power InGaAs Schottky Diodes in Full-Band Mixers at 0.3 THz

In this paper, we present and compare two different full-band WR3.4 Sub-Harmonic Mixers (SHMs), featuring traditional GaAs and the novel low-barrier InGaAs discrete diodes. In this study, an Active Multiplier Chain (AMC) is used as a Local Oscillator source, which provides peak powers beyond 20 mW. The GaAs mixer presents Single-Sideband (SSB) Conversion Loss (CL) of 10 dB and Double-Sideband (DSB) Noise Temperature (NT) of 3000 K across the entire RF and IF bands when an LO power of 6–10 mW is applied. The low-barrier mixer featuring the new and improved batch of InGaAs diodes performs SSB Conversion Loss of 15 dB and DSB Noise Temperature of 9000 K, using LO powers of 0.5 mW. In this work, a comparison of the CL and NT of both mixers is carried out, highlighting the excellent performances of GaAs diodes and the minimum LO power requirements needed by InGaAs counterparts, as well as future perspectives in InGaAs mixer performances. The mixers and diodes were fully designed, fabricated, and tested at ACST GmbH.

Analysis and Design of Novel 180° Hybrid for U-Band Monolithic Subharmonic Mixer in 0.15-μm GaAs pHEMT Technology

In this brief, a novel reduced-size 1800 hybrid is presented to implement a U-band subharmonic mixer (SHM) via a 0.15-μm GaAs pHEMT process. The isolations between Σ-port and -port of the proposed 1800 hybrid are significantly enhanced by two structures: one is a compact multiconductor edge-coupled line balun with artificial transmission line and the other is an in-phase power divider composed of λLO/4 coupled line. As a proof-of-principle demonstration, a single balanced SHM with an antiparallel diode pair configuration is designed and fabricated, which exhibits a conversion gain of -12.25 dB 1 1.55 dB within the operating RF frequency of 40 to 60 GHz under 14 dBm LO pumping power. The improved isolations of LO-to-RF and 2LO-to-RF are 33 to 47 dB and 44 to 57 dB, respectively. The measured results surpass previously reported performance of SHMs.

Co-Designed 138 GHz Compact CMOS Transmitter With Simplified Sub-Harmonic Mixer

Co-Designed 138 GHz Compact CMOS Transmitter With Simplified Sub-Harmonic Mixer

170 GHz quasi-optical sub-harmonic mixer with a back-to-back lenses packaging based on HDI.

The paper presents a 170 GHz quasi-optical sub-harmonic mixer with a 3D-printed back-to-back lenses packaging. The quasi-optical mixer is comprised by a pair of antiparallel GaAs Schottky diodes, a patch antenna for receiving local oscillator (LO) pump signal, a symmetric-slit patch antenna for receiving radio frequency (RF) signal, dual 3D-printed lenses and a matching network. The quasi-optical mixer with a pair of antiparallel GaAs Schottky diodes is designed on a multilayer build-up printed circuit board (PCB) utilizing commercially low-cost and high-density interconnect (HDI) technology. The LO and RF antennas are placed on the front and back of the multilayer build-up substrate, respectively, thus significantly simplifying the quasi-optical design. Furthermore, dual 3D-printed lenses placed back-to-back are proposed for LO and RF antennas radiation gain enhancement and mechanical robustness. Additionally, the buried planar reflectors in the substrate maintain effective radiation isolation between the antennas. For facilitating coupling efficiency of signal power into the Schottky diodes and signal isolation between the LO pump signal and RF signal, a compact matching network with low-loss quasi-coaxial via transition structure is integrated in the mixer circuit. The measured single-sideband conversion loss is from 11.3 to 15.4 dB in an operation range of 160 to 180 GHz. The measured radiation patterns agree well with the simulated results.

Phase Locking of a THz QC-VECSEL to a Microwave Reference

High resolution frequency study and phase-locking have been performed on a terahertz quantum-cascade vertical-external-cavity surface-emitting-laser operating around 2.5 THz. A subharmonic diode mixer is used to down convert the THz signal to a 100 MHz intermediate frequency that is phase locked to a stable 100 MHz microwave reference. Between 90-95% of the QC-VECSEL signal is locked within 2 Hz of the multiplied RF reference, and amplitude fluctuations on the order of 1-10% are observed, depending on the bias point of the QC-VECSEL. The bandwidth of the locking loop is ∼1 MHz. Many noise peaks in the IF signal are observed, likely corresponding to mechanical resonances in the 10 Hz-10 kHz. These peaks are generally -30 to -60 dB below the main tone, and are below the phase noise level of the multiplied RF reference which ultimately limits the phase noise of the locked QC-VECSEL.

Optical injection locking of a THz quantum-cascade VECSEL with an electronic source.

Optical injection locking of a metasurface quantum-cascade (QC) vertical-external-cavity surface-emitting laser (VECSEL) is demonstrated at 2.5 THz using a Schottky diode frequency multiplier chain as the injection source. The spectral properties of the source are transferred to the laser output with a locked linewidth of ∼1 Hz, as measured by a separate subharmonic diode mixer, and a locking bandwidth of ∼300 MHz is achieved. The large locking range is enabled by the microwatt power levels available from modern diode multipliers. The interplay between the injected signal and feedback from external reflections is studied and demonstrated to increase or decrease the locking bandwidth relative to the classic locking range depending on the phase of the feedback.

Анализ и разработка высокоточного генератора частоты w-диапазона с низким уровнем паразитных гармоник

For millimeter waves applications in the W-band 93.5-95.5 GHz, improved frequency synthesizers are highly demanded. Improved frequency synthesizer should be tunable synthesizer with high step resolution and possess high phase noise performance, low spurious harmonic levels and short locking time. These parameters are conflicting parameters in developing a high precision frequency oscillator with a pure spectrum. Therefore, it's necessary to make a compromisation between them. In this paper we present a frequency synthesizer based on a Gunn diode, two stable finely tuned frequency sources, a phase locked loop, and a 10th order subharmonic mixer in the feedback loop is built. The phase noise, spurious levels, and tuning step size of the phase locked loop generator are then analyzed, and the effect of each parameter on the others is introduced. To test the performance of the proposed frequency synthesizer using a spectrum analyzer, the output spectrum of the intermediate frequency was measured on a subharmonic mixer, which corresponds to the spectrum of a phase-locked loop generator. The results show that the proposed phase-locked loop generator can be tuned in steps of less than 1 Hz, and the first two spurious harmonics are far from the fundamental harmonic. These results can be used for designing an enhanced high precision frequency synthesizer with a low level of spurious harmonics and high phase noise performance in millimeter waves applications such as CW RADAR.

The Design Methods and Experiments for a 220-GHz Quasi-Optical Cryogenic Schottky Subharmonic Mixer of High Performance

In this article, we present systematic design methods and experimental verifications of a 220-GHz quasi-optical cryogenic Schottky subharmonic mixer. To maximize device performance over a wide bandwidth and overcome the difficulties in conjugate matching designs, an impedance optimization-based cooperative design method is proposed for such quasi-optical mixer that includes the on-chip antenna and heterodyne mixing circuit. A coplanar waveguide (CPW) tuning network is utilized and optimized to offset the parasitic reactance effect of Schottky diodes. Besides, a dual-band log-periodic-slot integrated lens antenna is presented for coupling the radio frequency and local oscillator radiations with high efficiency. A reversed field tracing method is proposed to acquire the position and size of the equivalent Gaussian waists at both frequencies, thus offering the guidance for optimizing the substrate thickness and lens dimensions for improved antenna gain and radiation pattern. A 220-GHz quasi-optical mixer prototype was fabricated and experimentally verified at both room and cryogenic temperatures. At 134 K, the single-sideband noise factor and the conversion loss are around 4.2–8.5 and 6–11 dB over a wide intermediate-frequency bandwidth of 0.5–20 GHz, showing the superior device performance at the comparable bands.

Study of the Optoelectronic Mixer Based on Modified Uni-Traveling Carrier Photodetector for Efficient Harmonic Mixing

We report the measurements and characterizations of optoelectronic harmonic mixing in a modified uni-traveling carrier photodetector (MUTC-PD). A systematic study of the bias voltage-dependent properties of the output power under different input optical power levels has been made and the proper operating conditions for different mixing modes have been investigated. In addition to the fundamental mixing, the higher-order harmonic mixing and RF subharmonic mixing products were obtained. The harmonic mixing mechanism is mainly attributed to the nonlinearity of the dependence of the output power on the bias voltage. Flat intermediate responses over a wide RF signal frequency range were measured for the fundamental mixing and the high-order RF subharmonic mixing. The feasible harmonic optoelectronic mixing in MUTC-PD shows great application potential in the wireless multichannel communication system.

A Compact Hybrid G-band Heterodyne Receiver Integrated with Millimeter Microwave Integrated Circuits and Schottky Diode-Based Circuits

This paper presents a compact hybrid G-band (170–260 GHz) heterodyne receiver module incorporating both Millimeter Microwave Integrated Circuits (MMICs) and a Schottky diode-based circuit. An on-chip sextupler and a Low Noise Amplifier (LNA), along with a diode-based Sub-Harmonic Mixer (SHM), are integrated into the demonstrated singular module, which is carefully designed and arranged with the co-simulations in electromagnetic and thermal domain. Through this methodology, a terahertz receiver module is fabricated with a volume of only 27 × 20 × 20 mm3. The measured results indicate that the double-sideband conversion gain of the receiver is 10.5–17.5 dB from 195 GHz to 230 GHz, while the noise temperature is 1009–1158 K. As a result, this terahertz receiver provides recorded miniaturized hardware applicable for terahertz Integration of Sensing and Communication (ISAC) systems.

A Novel 180–210 GHz Single Sideband Mixer Using Filtering Waveguide-Microstrip Transition Structure

In this letter, we proposed a novel 180–210 GHz single sideband (SSB) Schottky diode-based subharmonic mixer (SHM), which features in simpler structure and fabrication compared with existing methods. Image rejection of the 220–250 GHz upper sideband (USB), as well as impedance matching, was achieved by a filtering waveguide-microstrip transition structure at the radio frequency (RF) input, rather than using traditional waveguide filters. Eventually, the mixer was measured to show great performance, including a SSB conversion loss (CL) of 8–12 dB across the passband, and an image rejection ratio (IRR) of 15–35 dB.

A 262-GHz Wireless IFoF Uplink With Remote Down-Conversion Using Optically Generated Sub-THz LO

We experimentally demonstrate the feasibility of a 262-GHz wireless intermediate frequency (IF)-over-fiber (IFoF) uplink with frequency down-conversion at a remote antenna unit (RAU). To distribute many RAUs for the coverage of terahertz (THz) wireless communications, it is important to simplify the RAU for the THz uplink. The remote down-conversion with a subharmonic mixer and a uni-traveling carrier-photodiode (UTC-PD) is driven by two optical tone signals from the central office (CO). This can reduce the high-frequency and wideband devices of the networks. Instead of coherent detection, the RAU can be simplified with optical transmission and direct detection (DD) by using a conventional optical modulator and a photodiode (PD). We measured the phase noise of the system and compensated for it with blind phase recovery. Then, the error vector magnitudes (EVMs) of the received signals were measured as a function of THz Tx power, optically generated local oscillator (LO) power, and THz wireless link distance. Single-channel 45-and 30-Gb/s data transmission was achieved over a 5-km fiber and 1-m THz wireless link based on soft-(2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-2}$</tex-math> </inline-formula> ) and hard-decision (3.8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-3}$</tex-math> </inline-formula> ) forward error correction (FEC) thresholds, respectively.

A 38-GHz demodulator with high image rejection in 65 nm-CMOS process

AbstractA high image rejection 38 GHz demodulator in TSMC 65-nm CMOS process is presented. To achieve better than −40 dBc image rejection ratio (IRR), a low I/Q mismatch 45° LO power splitter of sub-harmonic mixer is proposed. In this design, the 45° LO power splitter is composed of a Wilkinson divider, a series delay line with electrical length of 45° on one side of the divider, and a shunt 90° transmission line on the other side. This configuration is attractive because of its design simplicity and easy fabrication. Compared with the conventional techniques that utilize capacitors and inductors instead of the shunt 90° transmission line, the proposed LO power splitter can alleviate the issue of process variation. The demodulator demonstrates an IRR lower than −40 dBc from 37.5 to 41.5 GHz. In addition, conversion gain is 1.3 ± 0.9 dB from 33 to 41 GHz with 6 dBm LO power. The total direct current power consumption is 78 mW from 1.0 V supply voltage. At the modulation scheme of 4096-QAM, the proposed demodulator demonstrates 1.7% (−35.1 dB) error vector magnitude (EVM), which is very close to the EVM measurement floor 1.6% (−36 dB) of our millimeter-wave signal analyzer.

Port‐assignment modelling of anti‐parallel Schottky barrier diode and 0.3‐THz sub‐harmonic mixer design

This letter presents a new port-assignment model of an anti-parallel Schottky barrier diode (AP-SBD) and a 0.3-THz sub-harmonic mixer (SHM) as the application design. Using the proposed method, the AP-SBD is accurately modelled compared to conventional modelling methods. Because the characteristics of an AP-SBD have the greatest impact on mixer performance, an accurate modelling method for AP-SBD helps design SHMs with good performance. To verify the proposed modelling in the terahertz region, a 0.3-THz SHM based on the modelled AP-SBD is designed and assembled. The measurement result reveals that the optimal double-sideband (DSB) conversion loss of the mixer is 6.7 to 10.1 dB within 279 to 318 GHz when the fixed local oscillator (LO) signal is 6.4 dBm at 152 GHz. All measurement results confirm that the proposed methodology is concise and feasible for the design of terahertz SHMs.