Non-linear control circuit
AssigneeNational Semiconductor Corporation
InventorMilton E. Wilcox
Life of this patent
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Abstract
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.
Claims4
A control circuit having a non-linear transfer characteristic as a function of an applied control potential, said circuit comprising:
- a differential amplifier stage having a differential control input, a common mode input, and an output;
- and
- a differential control stage having a differential output coupled to said control input of said differential amplifier stage, and a differential input, said differential control stage including a pair of transistors each constructed so as to have substantially different characteristics whereby the signal transfer characteristic from said common mode input to said differential amplifier stage output is a non-linear function of said potential applied to said input of said differential control stage.
Dependencies are inferred from the claim text.