Design of Charge Pump for Inertial Sensor Drive Circuit

Abstract

A transistor-level circuit design of charge pump is introduced to drive the inertial device. The design is made of several big modules, including main charge pump module, band gap reference module, comparator module, oscillating module, control module, temperature protection module. A three-stage charge pump is applied to achieve 5 V to 18 V DC/DC conversion, and each stage uses the cross coupled charge pump circuit, taking body effect, threshold voltage drop and efficiency into account. Considering efficiency and power consumption, the band gap reference module adopts a self-biased op amp. To make the comparator transient response fast, the op amp cascades two inverters. The temperature protection module sets a maximum temperature to protect the charge pump. The control module is composed of a data selector, a two-phase non-overlap clock circuit and a frequency divider to optimize clock signal. Then simulations are given and the charge pump is analyzed, finally the efficiency of charge pump is calculated. Designed in CSMC 0.5um process, the charge pump has an efficiency of 87.63 percent, a 19.85V output voltage, a 100 mA output current, and 6.05mV ripple.