Frequency Multiplier and Mixer MMICs Based on a Metamorphic HEMT Technology Including Schottky Diodes

Fabian Thome,Arnulf Leuther,Robert Iannucci,Frank Schafer,Alessandro Navarrini,Patrice Serres,Erdin Ture

doi:10.1109/access.2020.2965823

Abstract

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.

Highlights

Nonlinear circuits are core building blocks in several systems implementations
BROADBAND FREQUENCY TRIPLER monolithic microwave integrated circuits (MMICs) For broadband frequency multipliers, the suppression of unwanted harmonics can be a major challenge or even impossible if the suppression is primarily based on filtering of already generated harmonics
A major part of this analysis is the layout optimization of the integrated planar Schottky diodes without changing the existing High-electron-mobility transistors (HEMTs) processing

Summary

INTRODUCTION

Nonlinear circuits are core building blocks in several systems implementations. Due to a considerably wide atmospheric window, the W-band frequency range (75 GHz to 110 GHz) is appealing for a multitude of applications, such as radio astronomy, wireless communication, or radar systems. C2 is chosen to present a short circuit for RF and LO frequencies This improves the conversion gain and reduces the required LO drive power since the voltage swing of the RF and LO input signal mainly drops across the Schottky diodes. The LO blocking is important to avoid a loss of LO input signal into the RF path, which would increase the required LO drive, and to prevent possible standing waves of the LO signal in case the RF port is highly reflective for LO frequencies, e.g., below the cut-off of a WM-2540 (formerly WR-10) waveguide (νTE10 = 59 GHz). The low-pass filter at node 1 (LPF1) presents an open circuit for the RF input signal towards the LO supply path This improves the conversion gain of the mixer cell since the leakage of RF signal into the LO path is distinctly reduced. Measurements and simulations are in good agreement and exhibit a P1 dB of 5 dBm RF input power

BROADBAND FREQUENCY TRIPLER MMIC

Findings

CONCLUSION