HIGH VOLTAGE CHARGE PUMP REGULATION SYSTEM WITH FINE STEP ADJUSTMENT

摘要

A regulator system for a charge pump system divides the binary decoding into two branches. One controls a set of parallel connected resistors for fine output voltage steps. The other branch controls a serial resistor to provide the large step size. For example, a 9-bit digital input signal is split into 2 least significant for the fine adjustment and the other 7 bits for the larger adjustments. In the example of a 50mV step size, in one current path 2 bits of the binary input then control two parallel resistors for 50mV and 100mV step size, and in the other current path 7 bits are used for one-hot-decode control serial resistors to provide a 200mV step size. A unity gain operational amplifier and a high voltage device are added in between the two branches to decouple the parasitic capacitance of large parallel resistors from the other elements. Thus, the sensing node consequently has less parasitic capacitance and is more sensitive to output level movement, resulting in less ripple at the output node.