Temperature compensation circuit for a crystal oscillators.

摘要

1,094,768. Transistor oscillator circuits. STANDARD TELEPHONES & CABLES Ltd. Aug. 16, 1966, No. 36536/66. Heading H3T. A crystal controlled oscillator has its frequency stabilized against temperature variations by means of a voltage variable reactance, e.g. a varactor diode D3, whose reactance is controlled by the difference between the outputs of two temperature sensitive networks 1, 2. The network 1, comprising Zener diode D1 and negative temperature coefficient resistor RT, has a cubic law, and the network 2, comprising Zener diode D2 and positive temperature resistor RS, has a linear law. The outputs of the two networks are applied to a differential amplifier, the output from which controls the reactance of the varactor diode D3 in series with the crystal 5. The values of resistors R6, R7 and R4, R5 are adjusted to give correct working at normal temperatures.