US Patent 7545856 Current mode phase shifter, mixer and amplifier

An integrated circuit radio transceiver includes a phase shift block that is operable to produce a phase shifted current signal at an output of the phase shift block and a mixer with a low input impedance that is operable to produce a phase and frequency shifted output current signal based upon the phase shifted current signal. One aspect of the present invention is that the phase shift block produces an output as a current signal and the mixer block is operably disposed and formed to receive the current signal produced by the phase shift block. Similarly, an operational amplifier configured in a low input impedance mode is provided to receive and amplify a current signal mixer output, all to maximize signal processing head room reduce circuit noise and improve linearity.