Patent ID: 7030709
Filing Date: 2006-04-18
Classification: H03B

Abstract:
1. An inverter oscillator circuit for delivering an alternating output signal, this inverter oscillator circuit including a parallel arrangement, between an input terminal and an output terminal, of an inverter amplifier means, a resonator and a resistor, first and second load capacitors being respectively connected between said input and output terminals, on the one hand, and a supply potential, on the other hand, said inverter amplifier means including a first inverter having a first transconductance value, permanently connected between said input and output terminals, and a second inverter having a second transconductance value, this inverter oscillator circuit further including control means for controlling said inverter amplifier means such that it has a so-called start-up transconductance value during a start-up phase and a so-called reduced transconductance value, lower than said start-up transconductance value, in steady state at the end of said start-up phase, said control means including switching means arranged to connect said second inverter between said input and output terminals during said start-up phase and for disconnecting said second inverter in steady state at the end of said start-up phase, wherein the inverter oscillator circuit further includes an amplitude control loop for smoothing an amplitude decrease in the output signal resulting from the passage of said start-up transconductance value to said reduced transconductance value, said amplitude control loop being connected to said first inverter and controlling the amplitude of said alternating output signal in steady state, wherein said amplitude control loop comprises an amplitude control circuit connected to one of said input and output terminals and delivering a control signal to at least one current source arranged in said supply path of the first inverter, and wherein at least one resistor element is connected in series in the supply path of said first inverter in parallel with said at least one current source.