Integrierte temperaturkompensierte Kristalloszillatorschaltung

A summing amplifier (310) of a temperature compensated voltage-controlled crystal oscillator circuit is provided with an integrated low-pass filter. A very high-value integrated resistance (Ron, M2) is provided at the input of the summing amplifier (310) so that the control voltages to be summed are applied through respective series resistors (R1,R2,R3) to one terminal of said integrated resistance and then further through the integrated resistance to the inverting input of the summing amplifier. Further, a feedback capacitor (C) is connected between the inverting input and an output of the summing amplifier (310). In the preferred embodiment of the invention, the integrated resistance is provided by the on-resistance (Ron) of a mosfet transistor (M2).