Digital controlled xtal osc

摘要

An unlimited number of steps or increments of given size are obtained in a delay line for phase alignment of, for instance, the signal from a crystal oscillator by momentarily switching between two parallel delay lines. One delay line operates as an active or enabled delay line while the other line is disabled or inactive. It is ensured at the same time that the inactive delay line produces a signal which has the same relative phase as the active delay line, this absolute phase differing by Nx2 pi , where N is a positive or a negative integer other than zero. The active delay line operate constantly within its regulation range and the phase of the local oscillator can be kept continuously locked to the phase of the reference signal.