A Broadband THz On-Chip Transition Using a Dipole Antenna with Integrated Balun

Abstract

A waveguide-to-microstrip transition is an essential component for packaging integrated circuits (ICs) in rectangular waveguides, especially at millimeter-wave and terahertz (THz) frequencies. At THz frequencies, the on-chip transitions, which are monolithically integrated in ICs are preferred to off-chip transitions, as the former can eliminate the wire-bonding process, which can cause severe impedance mismatch and additional insertion loss of the transitions. Therefore, on-chip transitions can allow the production of low cost and repeatable THz modules. However, on-chip transitions show limited performance in insertion loss and bandwidth, more seriously, this is an in-band resonance issue. These problems are mainly caused by the substrate used in the THz ICs, such as an indium phosphide (InP), which exhibits a high dielectric constant, high dielectric loss, and high thickness, compared with the size of THz waveguides. In this work, we propose a broadband THz on-chip transition using a dipole antenna with an integrated balun in the InP substrate. The transition is designed using three-dimensional electromagnetic (EM) simulations based on the equivalent circuit model. We show that in-band resonances can be induced within the InP substrate and also prove that backside vias can effectively eliminate these resonances. Measurement of the fabricated on-chip transition in 250 nm InP heterojunction bipolar transistor (HBT) technology, shows wideband impedance match and low insertion loss at H-band frequencies (220–320 GHz), without in-band resonances, due to the properly placed backside vias.

260‐GHz waveguide module containing an integrated InP HBT amplifier chip

“…The loss is mainly due to the conductor loss of the InP chip microstrip lines. This 3-dB loss is consistent with previous simulation results performed on the InP-integrated thru-line at 300 GHz [3]. However, the measured data also plotted in Fig.…”

“…The amplifier module successfully produced positive gain with significant amount of power, but the off‐centred transitions and tandem couplers also introduced an excessive 10 dB of insertion loss near 300 GHz. Later, a different module for an InP chip with a pair of transitions connected using a microstrip thru‐line section showed an improved insertion loss of 4 dB covering full WR‐3.4 band [3]. In this Letter, we investigate an array of miniaturised dipole transitions connected to three amplifier chains all integrated on a single InP chip for direct power combining inside a WR‐3.4 waveguide.…”

A Novel Tangential Electric-Field Sensor Based on Electric Dipole and Integrated Balun for the Near-Field Measurement Covering GPS Band

“…Therefore, a balun is needed to achieve the transformation from the balanced to the unbalanced. Various types of baluns [34,35,36,37,38,39] have been designed to convert a balanced signal into two unbalanced signals with an equal amplitude and inverse phase. It should be noted that comparing the advantages of these baluns and then finding out the optimal one is not the focus of this paper.…”

Resonant Tunneling Diode (RTD) Terahertz Active Transmission Line Oscillator with Graphene-Plasma Wave and Two Graphene Antennas

“…Terahertz (THz) electromagnetic radiation is generally composed of electromagnetic waves with frequencies of 100 GHz-10 THz [1]. The wavelengths of THz waves fall between those of light waves and millimeter waves.…”