Monolithically integrable, amplitude-controllable oscillator amplifier circuit

Claim 1

Monolithically integrable amplitude-controllable oscillator amplifier circuit, comprising a differential amplifier including first, second and third transistors each having an emitter contact, a collector contact and a base contact; said emitter contacts of said first and said second transistors being interconnected, a frequency-determining circuit element connected to said base contact of said first transistor, said base contacts of said first, said second and said third transistors being acted upon by a direct voltage, a first capacitor connecting said base contact of said second transistor to a reference potential, said frequency-determining circuit element being connected to said collector contact of said second transistor, said frequency-determining circuit element being connected to the oscillator amplifier, said collector contact of said first transistor being connected directly to said emitter contact of said third transistor forming a cascode circuit, said collector contact of said third transistor being connected to a first potential, said collector contact of said second transistor forming a first amplifier output providing a first output signal, a first resistor connected between said collector contact of said second transistor and a second potential; a first current source connected between said interconnected emitter contacts of said first and said second transistors and the reference potential, said first current source being formed of a series circuit of a second current source, a first constant current source and a circuit node connected between said second current source and said first constant current source; and a control circuit for the oscillator amplifier controlling amplitude as a function of the output signal, said control circuit including a control element having a first voltage-controlled current source with a control voltage input, a current input and a current output; a controller feeding a control variable to said control voltage input of said first voltage-controlled current source, said current input of said first voltage-controlled current source being connected to a third potential, and said current output of said first voltage-controlled current source being connected to said first circuit node.