SYSTEM AND METHOD FOR AN IMPROVED QUADRATURE UPCONVERTER FOR I/Q MODULATION USING INTERMEDIATE FREQUENCY CARRIERS

摘要

A signal transmitter for sending a radio signal is made up of an input for receiving input data and a first circuit for generating an inphase signal (I) and a quadrature signal (Q) from the input data. An upconverter having first through fourth modulators upconverts the (I) and (Q) signals. A first and second combiners combine the respective outputs from the modulators to generate a first and second intermediate signals. A quadrature modulator converts the first intermediate signal and the second intermediate signal to an output signal. The output signal has a component at a first sideband of a second frequency, the first sideband frequency offset from the second frequency by a first amount. A filter, coupled to the quadrature modulator, passes the first sideband, and filters the second frequency and a second sideband, the second sideband offset from the second frequency by the inverse of the first amount.