A 220 GHz Low Reflection Modulator Based on an On-Chip Annular Resonant Branch Structure

This paper presents a terahertz direct amplitude modulator with GaAs process, combining microstrip lines and Schottky diodes to form an integrated ring resonator low return loss structure. This modulator controls Schottky diode by adjusting the bias voltage, thereby regulating the resonance characteristics of the annular junction where the Schottky diode is located, and achieving low-reflection modulation of terahertz waves. Simulation results show that the circuit can achieve a switch ratio of over 12 dB in the 215–225 GHz frequency range, with an insertion loss of less than 2.2 dB. The reflection coefficients corresponding to the on and off states are both less than −18 dB. The maximum switch ratio at 220 GHz reaching 26dB and the reflection coefficients for the on and off states both below –28 dB.