Ring oscillator substrate bias generator with precharge voltage feedback control

摘要

A generator circuit for producing a negative bias voltage on a substrate for a semiconductor device employs a multistage on-chip oscillator driving individul charge pump circuits for each stage. The oscillator may produce a frequency related to the value of the negative bias, using a feedback circuit. Each of the charge pump circuits includes a capacitor and an MOS diode coupled to the substrate and another diode coupled to the ground terminal of the supply.