Design of novel fully-differential charge pump

A new novel fully-differential charge pump was designed in this paper, differential input and differential output was used in this circuit. The differential output circuit not only reduced the voltage noise created by leakage current, but also increased the ascending/descending speed and the range of output voltage. In the differential input, positive feedback circuit was used to increase the switching speed and attain low power. The circuits of pump-up and pump-down are symmetric to overcome the disadvantage of mismatch between charge and discharge current. The circuit was simulated by the Spectre in Cadence with 0.18 ¿m process, BSIM3V3 model parameters. When VDD = 1.8 V, f = 100 MHz, I_S = 20 ¿A, the range of output voltage is -1.8 V~+1.8 V, and has great linearity and stable step in the rang of -1.4 V~+1.4 V. In addition, the power is only 0.07 mW.