A series/shunt switching type sample and hold CMOS IC for 1 GHz-band direct RF under sampling reception

A series/shunt switching type sample and hold (S/H) CMOS IC for direct RF under sampling reception is presented. The series/shunt configuration enable lower loss of S/H circuit and lower leakage of RF signal into the S/H output. The optimum transistor size of switches is selected by using circuit simulation. The timing of series/shunt switching is discussed and delay circuit using 1-stage inverter is added to the shunt switch control circuit to satisfy the required delay time. The proposed and designed S/H circuit is fabricated in 90nm CMOS process. The measured results using 1 GHz-band RX signal show good agreements with simulation.