Gate-assisted high-Q-factor junction varactor

In this letter, we demonstrate a high-performance gate-assisted junction varactor. The gate plays an important role in the varactor; it can decrease the series resistance and enlarge the junction capacitance of this device. With the assistance of a positive-biased gate, the Q-factor of a varactor with 723 fF capacitance at 2.4 GHz is as high as 108. Its tuning ratio is 30.1% when it is operated in the range of 0.5 to 2.5 V.