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 0.13 μm CMOS process at 1.5 V 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.