CMOS RF Switch with Fast Discharge Feature

A radio-frequency (RF) switch featuring a circuit for fast discharge of the gate oxide capacitance is presented in this letter. Two auxiliary transistors are added between the gate and source/drain terminals of the main switch. They are brought into the ON state for a short time at the beginning of the switching transient, discharging the gate of the main transistor, and speeding up the switching process. An integrated circuit implementing the proposed concept based on a large shunt switch has been designed and fabricated in Infineon 130-nm bulk-CMOS RF-switch technology. The measurements have demonstrated improvement in switching time (defined as the time between the control signal trigger edge and 90% of the target RF amplitude) of above 50% with no penalty in RF performance comparing to the conventional switch without discharge feature. The measured OFF-state insertion loss and ON-state isolation at 824 MHz were 0.12 and 27.2 dB, respectively.