Patent ID: 6362698
Filing Date: 2002-03-26
Classification: H03B,H03K,H03L

Abstract:
A voltage-controlled oscillator (VCO) circuit, comprising:an LC tank oscillator enabled to produce an oscillation at a controlled frequency in response to a conditioned control voltage output signal received at an input; an amplification circuit comprising a two-stage amplifier including a first amplification stage having an input to receive an oscillation control voltage signal and an output connected to an input of a second amplification stage, said second amplification stage comprising a first active cascode structure having an input coupled to the output of the first amplification stage, a diode-connected transistor connected to an output of the two-stage amplifier and connected in series with a resistor tied to a reference voltage to produce the conditioned control voltage output signal at an output, said conditioned control voltage output signal substantially equaling a voltage level of the oscillation control voltage signal; and a clamping circuit to clamp the conditioned control voltage output signal from falling below a predetermined level.