Patent ID: 6972610

Claim:
A radio frequency (RF) circuit for receiving an input signal, and producing a differential mixer output signal using the input signal, the RF circuit comprising: a first plurality of transistors arranged in a ring configuration, each of the first plurality of transistors comprising a first electrode of a first type and a second electrode of a second type; and a second plurality of transistors, each of the second plurality of transistors comprising a first electrode of the second type and a second electrode of the first type, wherein the first electrode of the second type electrode of each of the second plurality of transistors is coupled to the first electrode of the first type of a different one of the first plurality of transistors and the second electrode of the second type of each of the second plurality of transistors is coupled to the second electrode of the first type of a different one of the first plurality of transistors, wherein the first and second plurality of transistors receive the input signal and a drive signal, and process the input signal and the drive signal to produce the differential mixer output signal having a frequency which is a function of frequency of the input signal and frequency of the drive signal, wherein the second plurality of transistors reduce a resistance of the first plurality of transistors, wherein the drive signal includes a local oscillator (LO) drive signal and a complementary LO drive signal, the RF circuit further comprising an LO buffer for producing the LO drive signal coupled to a control electrode of each of a first pair of the first plurality of transistors and each of a first pair of the second plurality of transistors and for producing the complementary LO drive signal coupled to a control electrode of each of a second pair of the first plurality of transistors and each of a second pair of the plurality of transistors, wherein the LO buffer comprises a high swing inductively loaded LO buffer, wherein the LO buffer comprises a differential pair of LO buffer transistors, each coupled between a positive voltage source and ground through an inductive load, coupled between a positive voltage source and ground, and wherein the LO buffer further comprises a plurality of LO buffer outputs and a LO buffer voltage limiter coupled to the LO buffer outputs, the LO buffer voltage limiter limiting a common mode voltage of the LO drive signal arid the complementary LO drive signal.