Non-linear control circuit

摘要

A low-Q mechanical resonator is operated in its series resonance mode in a circuit that includes an amplifier and voltage variable phase shifter. As the phase shift is varied, the resonator will shift its frequency to compensate the phase shift. The result is a voltage variable oscillator frequency. The low-Q resonator has a non-linear phase versus frequency characteristic so that frequency is not a linear function of control voltage. A plural emitter transistor is employed in one side of a non-linear differential control amplifier. The resulting non-linear transfer characteristic is used to compensate the non-linear oscillator characteristic so that the frequency versus control voltage is linear.