communication terminal (710) includes a coder (722, 724) receiving an input signal and having an output terminal for providing a coded signal; an upconverter core (100) having an input terminal for receiving a first signal having predetermined spectral content at an input frequency and an output terminal for providing an output signal having substantially the predetermined spectral content at a higher frequency using a local oscillator signal having a carrier frequency; an electrical measurement circuit having an input terminal coupled to the output terminal of the upconverter core (100), and an output terminal for providing a first offset correction signal representative of a power of the output signal at the carrier frequency; and a summing device (406) having a positive input terminal for receiving the coded signal, a negative input terminal coupled to the output terminal of the electrical measurement circuit, and an output terminal coupled to the input terminal of the upconverter core (100).