Self excited reference or calibration oscillator - has two phase shifting stages whose gains are constant and independent of oscillator frequency

摘要

The oscillator is in the form of a phase shifter delivering polyphase balanced voltages. It consists of a feed-back loop with one phase shifting stage with constant gain, a second phase shifting stage with constant gain and adjustable phase shift depending on the oscillator frequency, and a basisc amplifier whose phase shift is zero or a multiple of 360 deg. Its gain is constant, and the total transmission function is such that at the required oscillator frequency the total gain is one, and total phase shift is 0 or 180 deg. Gains of the two phase shifting stages (2, 3) are constant and independent from oscillator frequency. They are determined only by the circuit parameters and need not readjustment. Phase shift (psi) generated by the first phase shifting stage (2) is held constant by fine adjustment independent from frequency.