Abstract: An improved integrated circuit oscillator adapted for crystal-controlled applications eliminates the need for capacitors and duty cycle control circuitry by using a cascaded pair of push-pull complementary transistor amplifier stages, a clipping-type automatic amplitude control circuit, and a resonant feed back path between the two amplifier stages. In an illustrative embodiment, floating bias voltages are established by a chain of diodes, with several bias currents set with respect to the chain current by emitter area relationships. Square-wave output is provided by a flip-flop connected to push-up and pull-down output circuits.

Abstract: A precision crystal-controlled oscillator circuit with provision for separate sinusoidal and square-wave output signals which can be realized as a silicon integrated circuit without the use of external capacitors or resistors is disclosed. Two feedback loops are utilized in addition to the oscillating loop. The first feedback loop maintains the gain of the oscillation loop at substantially unity when the amplitude of the oscillation is at a predetermined level, thereby ensuring both spectral purity and amplitude stability of the sinusoidal output signal. The second feedback loop maintains the duty cycle of the square-wave output signal substantially equal to 50 percent by controlling the circuit operation to equally space the signal zero crossings at the input of the square-wave output stage.