Parametric Phase-Locked OscillatorߞCharacteristics and Applications to Digital Systems

The ability of the Parametric Phase-Locked Oscillator (PLO) to detect, amplify, and store binary digital signals, in the form of two distinct phases of a carrier, makes it possible to use the device as the sole component in a digital computer system. The variable-capacitance version of the device operates readily at kilomegacycle frequencies, thus forming the basis of a digital computer at a kilomegapulse clock rate. In the present paper the results of an investigation of the behavior and possible applications of the variable-capacitance PLO are presented. The investigation was supported by experimental work with lumped-component variable-capacitance PLO's at 5 mc, and microwave variable-capacitance PLO's at 4 kmc. The steady-state behavior of the device is described; variations of the output voltage with pump voltage, loading, tuning and frequency variations are presented in the form of characteristic curves. Results indicate that the device is rather insensitive to reasonable changes in operating conditions and parameter values. The transient behavior of the PLO shows that the device can be switched in a number of different ways. Five such modes of operation are discussed; these are phase initiation, forced switching, burst generation, tri-stable operation and unconditional switching. Each of these modes has particular advantages for various applications. Switching times of the order of 3 to 10 cycles of the signal frequency are readily obtainable. The various modes of operation of the device suggest a number of applications both in logic and in memory.