Design of RC Time Constant Measuring Circuit in RF IC for GSM

To deal with device error caused by IC process,an RC time constant measuring circuit was designed for poly-phase filter module in GSM system.In this circuit,programmable capacitor arrays were used to rapidly tune parameters,which ensured stability of the module.Simulation results showed that,with 5 CNC mode tuning capacitor arrays,the tuning time error was no more than three clock cycles,which meets requirements of the system.