Modeling of TTL Inverter Amplifiers as Applied to Overtone Crystal Clock Oscillators,

Methods have been developed for analysis of clock oscillator circuits which utilize TTL inverter gates as active devices. Equivalent circuit parameter values have been measured for Schottky TTL inverter amplifiers and used in computer analysis of oscillator circuits. Computer optimization of third overtone oscillators has been done using the models developed for the TTL inverters. The basic circuit consists of a biased TTL inverter driving a notch filter with a coupled dual monolithic resonator completing the feedback loop back to the amplifier input. Tuning the notch filter to the fundamental crystal frequency inhibits fundamental mode oscillations and allows third overtone mode oscillations to occur. Several variations of this circuit have been computer analyzed and empirically tested yielding good performance for third overtone mode oscillators.