Abstract: A small and economically fabricated CMOS voltage controlled crystal oscillator is provided by coupling three inverter amplifiers in series with a regenerative crystal controlled feedback loop. The first and second CMOS inverters have output nodes whose impedances are modified by a CMOS impedance modulating circuit. Also coupled to each of these two output nodes is a CMOS transistor shunt capacitor. The impedance of the output node is modified according to the magnitude of a voltage control signal applied to the CMOS modulating circuits. The self-bias of the modulating circuits is maintained substantially constant by adjusting the gate drive in each of the modulating circuits according to gate drives derived from a dummy modulating circuit.

Abstract: An input receiver circuit in a read-only memory is provided with a feedback to control hysteresis. A second stage and an additional output is added to the receiver. Switching circuit noise from inside of the read-only memory is isolated by the added state and outputs, and cannot be fed back into the receiver circuit to affect the detection of the TTL voltage levels. Use of wide and long FET sizes minimizes the manufacture related variations in the input receiver switching levels.