Patent ID: 7580478

Claim:
An I/Q modulator that employs current-mixing for a direct conversion wireless communication transmitter, the modulator comprising: one or more voltage-to-current converters for receiving a digitally modulated and D/A converted voltage level signal and for convening the voltage level signal to a current level signal to be output; one or more current sources for providing a predetermined current, each of the voltage-to-current converters comprising a CMOS transistor connected in parallel with a corresponding one of the one or more current sources between a common node and ground, a gate of the CMOS transistor receiving the voltage level signal, wherein a signal to be modulated is provided at the common node as a difference between the predetermined current provided by the corresponding one of the one or more current sources and the current level signal; a local signal providing unit for providing a local signal having one or more phases; and one or more frequency mixing units for mixing the local signal having the one or more phases and the signal to be modulated provided at the common node of a corresponding one of the one or more current sources and a corresponding one of the one or more voltage-to-current converters.