Microwave Group Delay Time Adjuster

This paper presents a method to control group delay time using a resonance circuit. The group delay time adjuster (GDTA) that can control signal group delay time comprises a variable capacitance and a variable equivalent inductor. These are coupled in parallel at a node and also controlled by two bias voltages separately. A variable equivalent inductor has realized a transmission line terminated a variable capacitor. Group delay time can be controlled by change of capacitance and inductance, but the resonating frequency is fixed. When the proposed GDTA is fabricated on RFID Korean frequency band (908.5~914MHz), a group delay variation is obtained about 3ns