Threshold Insensitive Oscillator Circuit
Original Publication Date: 1979-Oct-01
Included in the Prior Art Database: 2005-Feb-20
A threshold-insensitive oscillator is disclosed for use in a substrate voltage generator circuit. Frequently, in existing substrate voltage generator circuits, the oscillator powering the circuit is difficult to start because the substrate voltage is at zero potential and, therefore, the threshold of the FET devices making up the oscillator is different from its normal operating value. The figure illustrates an oscillator made up of all depletion-mode FET devices which are always turned on independent of the substrate voltage. With the disclosed circuit, a substrate voltage generator circuit on a semiconductor chip may be powered on reliably.