A Ka-Band Distributed Voltage-Controlled Oscillator With Constant 15-dBm Output Power

摘要

A 27-GHz monolithic distributed oscillator based on the reverse-gain mode of a distributed amplifier is presented. The backward current in the drain line, which is typically absorbed by a drain resistor, is purposely used as a feedback signal to drive oscillation. The derived on-set oscillation condition shows that the transconductance of transistor and feedback length determine the oscillation frequency. This brings an advantage of frequency tuning solely by controlling the gate bias voltage. The proposed feedback from the backward current also brings layout convenience due to the close location of the backward current node and the gate node. A three-stage distributed oscillator is designed with the 0.1μm-pHEMT process to demonstrate the proposed method. The measured 15±0.9 dBm output power is obtained for oscillation frequency tuned from 26.4 GHz to 27.4 GHz.