Patent ID: 7298224

Claim:
An amplifier circuit having an amplifier input and an amplifier output for an oscillator having an oscillating frequency in a defined oscillating frequency range, comprising: a set of at least three transconductors, wherein the transconductors are configured to map an input voltage to an output current considering a transconductance of the set of at least three transconductors, wherein at least one transconductor has a positive transconductance, and wherein at least one other transconductor has a negative transconductance, and wherein the transconductors together provide a positive amplification; wherein a first transconductor has an input coupled to the amplifier input, wherein a second transconductor has an input coupled to an output of the first transconductor and has a feedback connection from an output of the second transconductor, wherein a third transconductor has an input coupled to an output of the first transconductor and an output of the second transconductor, and wherein at least a first passive impedance element is coupled to the output of the first transconductor, wherein the transconductance and the at least first impedance element are dimensioned so that, in the defined oscillating frequency range, a given phase difference is present between a signal at the amplifier input and a signal at the amplifier output.