This paper reports on the monolithic integration of layout-optimized Schottky diodes realized in an established 50-nm gate-length metamorphic high-electron-mobility transistor technology for use in multifunctional nonlinear circuits. The suitability of the realized Schottky diodes is demonstrated by a broadband millimeter-wave I/Q-mixer (In-phase/Quadrature) and local oscillator (LO) chain comprising two power amplifiers and a frequency tripler, fabricated on monolithic microwave integrated circuits (MMICs). Both circuits are based on an anti-parallel Schottky diode topology. The subharmonically-pumped I/Q-mixer covers an RF (radio frequency) and IF (intermediate frequency) range of at least 75 GHz to 110 GHz and 0.5 GHz to 15 GHz, respectively. The single-sideband conversion loss is between 14 dB and 16 dB across most of the entire RF and IF bands. The core of the LO chain consists of a frequency tripler (multiplier by three) and features a bias-adjustable output power with almost constant conversion efficiency and a control range of more than 8 dB. The fully-integrated LO chain MMIC matches the needs of the presented I/Q-mixer and exhibits an average output power of 16.3 dBm with a covered frequency range of 38 GHz to 60 GHz. The unwanted harmonics are suppressed by at least =25.9 dBc below the third harmonic for the entire frequency range and better than =32.1 dBc for most part of the band. Thus, the mixer and tripler MMICs demonstrate state-of-the-art performance with regards to, e.g., covered bandwidth, output power, harmonic suppression, or 1 dB compression point.
In this paper, we describe a measurement setup to characterize the intermediate frequency (IF) impedance of cryogenically cooled superconductor-insulator-superconductor (SIS) mixers. A setup based on a commercial vector network analyzer (VNA), a circulator and a low noise amplifier (LNA) has allowed to increase the dynamic of the VNA and to perform accurate one-port measurements across a high dynamic range of the SIS mixers IF band. The mixers were biased in three different regions of their unpumped IV curve to obtain three known impedances which are close to the classical calibration SOLT standards (Short, Open, Load, Thru): the reference plane was located at the SIS junction itself and the calibration procedure allowed to calibrate out all IF circuitry of the measurement setup, including the on-chip SIS mixer intrinsic capacitance and inductance without requiring to thermally cycle and open the cryostat to locate and measure the different calibration standards. Thus, the devised method provides a simple and direct measurement of the SIS mixers IF impedance which can be used for quick, accurate and highly repeatable IF characterization of any type of millimeter and sub-millimeter wave SIS mixers. The measurement method is described and the experimental results of the IF output impedances of 3 mm band DSB and SSB mixers with 4 GHz wide IFs (across 4-8 GHz) are presented and compared with simulated predictions obtained from combining Tucker's SIS mixer theory and accurate electromagnetic modeling of the mixer structure. Index Terms-Double side band (DSB) and single side band (SSB) tuning, intermediate frequency (IF) impedance, superconductor-insulator-superconductor (SIS) mixer, vector network analyzer (VNA) measurements.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.