Patent ID: 7038547

Claim:
A circuit, comprising: an amplifier having an output for providing an amplified modulated signal having a carrier frequency; and a D.C. bias circuit comprising: a decoupling capacitor having a first terminal coupled to the output of the amplifier and to a voltage supply terminal, the decoupling capacitor providing an open circuit at the carrier frequency; and a low frequency decoupling capacitor coupled to the output of the amplifier at a location between the output of the amplifier and the first terminal of the decoupling capacitor; wherein the D.C. bias circuit further comprises: a transmission line having a first end coupled to the output of the amplifier and a second end coupled to the first terminal of the decoupling capacitor; wherein the carrier frequency has a wavelength; wherein a distance between the first end and the second end is equal to N times the wavelength divided by four, where N is an odd integer; wherein the low frequency decoupling capacitor is coupled to the transmission line between the output of the amplifier and the second end.