A low ripple four-phase charge pump design driven by a phase-shift clock

Aiming at the shortcomings of the traditional four-phase clock charge pump with large ripple, a new charge pump structure is proposed which is driven by phase-shifting clock ticking. The main body of the charge pump adopts two sets of complementary parallel structure of the four-phase charge pump, and the output stage adopts a cross-coupling structure, eliminating the last stage threshold voltage loss. In addition, the NMOS connected to the diode is added as an auxiliary tube at each stage output node, increasing precharge and shortening the establishment time. The charge pump system is different from the traditional single clock drive charge pump, using a phase shift clock to drive multiple branches in parallel charge pump, time-sharing charging of the output node to reduce the load capacitance charge and discharge time, reduce the output voltage ripple. The cadence Spectre simulation results based on the SMIC 65 nm process show that the input voltage of the circuit is 1.8 V, the clock is 50 MHZ, the output target voltage is 10 V, the load capacitance is 50 pF, and the output voltage ripple is only 2 mV at a current drive capability of 400 uA. It has the advantage of low ripple.