A Low Voltage Switched-Capacitor Current Reference Circuit with low dependence on Process, Voltage and Temperature

A low voltage switched-capacitor circuit that generates an almost constant reference current across process, voltage and temperature (PVT) is proposed. The reference voltage is generated by a low voltage band-gap circuit. The output reference current is obtained by applying the generated reference voltage to a low voltage V – I converter. The resistor in the proposed V – I converter is further replaced by a switched capacitor resistor. Due to less variation in the capacitor value across PVT’s and high accuracy in integrated voltage reference, the output reference current remains fairly constant. The circuit has been designed in 0.13u CMOS process at 1.5V supply voltage. The simulation results show that the output reference current is quite insensitive to PVT and varies linearly with clock frequency and capacitor value of the switched capacitor resistor.