Charge pump substrate bias with antiparasitic guard ring

Claim 1

A self-substrate bias circuit semiconductor device comprising: a semiconductor substrate of a first conductivity type; an oscillator fabricated on said semiconductor substrate for generating pulse signals; a rectify-charge pump circuit section fabricated on said semiconductor substrate and including a coupling capacitor connected to said oscillator to be supplied with pulse signals, a first field effect transistor connected between said capacitor and a reference voltage source, and a second field effect transistor connected between said capacitor of said substrate and said substrate; and a semiconductor region of a second conductivity type formed in said semiconductor substrate to surround said rectify-charge pump circuit section and to function as a capacitive region and a source region for said first field effect transistor, said semiconductor region being connected to said reference voltage source for functioning as a capacitive guard ring that absorbs fluctuating minority carriers generated from said rectify-charge pump circuit.