Looped circuit and associated method for controlling the relationship between current and capacitance in CMOS and BICMOS circuit design

摘要

A looped circuit for generating a variable bias voltage. The looped circuit includes a variable current source having a current output that is dependent upon the variable bias voltage. The looped circuit also includes a capacitor that is periodically coupled to the current source for a predetermined period of time, wherein the current source charges the capacitor during each predetermined period of time. At least one subcircuit is provided for varying the variable bias voltage, wherein the variable bias voltage automatically causes the current source to charge the capacitor to a predetermined reference voltage during each predetermined period of time. Accordingly, the generated bias voltage will vary with temperature and other external variables. However, the ratio of the current produced by the current source divided by the capacitance of the capacitor is equal to the ratio of the predetermined reference voltage divided by the referenced predetermined period of time. This ratio remains constant regardless of variations in process and temperature.