Patent ID: 7542521

Claim:
A direct-conversion frequency mixer comprising: a 1 st frequency mixing unit (FMU) for direct-converting a single phase radio frequency (SPRF) signal into an in-phase baseband signal by using quadrature local oscillation (QLO) signals having respective phases of 0 degrees and 180 degrees such that the 1 st FMU comprises 1 st , 2 nd , 3 rd , and 4 th transistors, the 1 st and 4 th transistors of the 1 st FMU having gates coupled to 0 and 180 degree phase QLO signals, respectively, the 2 nd and 3 rd transistors of the 1 st FMU having gates coupled to the SPRF signal, wherein the 1 st and 2 nd transistors of the 1 st FMU having drains commonly coupled together and coupled to a bias voltage (VDD) such that a common drain node of the 1 st and 2 nd transistors of the 1 st FMU for outputting a positive in-phase baseband (IP+BB) signal, the 3 rd and 4 th transistors of the 1 st FMU having drains commonly coupled together and coupled to the VDD such that a common drain node of the 3 rd and 4 th transistors of the 1 st FMU for outputting a negative in-phase baseband (IP−BB) signal; and a 2 nd frequency mixing unit (FMU) for direct-converting SPRF signal into a quadrature-phase baseband signal by using QLO signals having respective phases of 90 degrees and 270 degrees such that the 2 nd FMU comprises four transistors, the 1 st and 4 th transistors of the 2 nd FMU having gates coupled to 90 and 270 degree phase QLO signals, respectively, the 2 nd and 3 rd transistors of the 2 nd FMU having gates coupled to the SPRF signal, wherein the 1 st and 2 nd transistors of the 2 nd FMU having drains commonly coupled together and coupled to the VDD such that a common drain node of the 1 st and 2 nd transistors of the 2 nd FMU for outputting a positive quadrature phase baseband (QP+BB) signal, and the 3 rd and 4 th transistors of the 2 nd FMU having drains commonly coupled together and coupled to the VDD such that a common drain node of the 3 rd and 4 th transistors of the 2 nd FMU for outputting a negative quadrature phase baseband (QP−BB) signal; wherein the 1 st FMU and the 2 nd FMU are driven by the VDD supplied from a single voltage source and wherein the 1 st FMU and the 2 nd FMU are parallel to each other and not stacked relative to the VDD.