Patent ID: 7974599

Claim:
A radio frequency integrated circuit (RFIC) comprises: a receiver section, when enabled, converts inbound radio frequency (RF) signals into inbound baseband signals, the receiver section including a low noise amplifier comprising: an input transistor having a gate coupled to receive the inbound RF signals, a source, and a drain operable to produce amplified RF signals; an inductor coupled between a power supply and the drain; and a current sink coupled between the source and a circuit ground, wherein a real component of input impedance of the low noise amplifier is substantially constant when the receiver section is enabled as when the receiver section is disabled; a transmit section, when enabled, converts outbound baseband signals into outbound RF signals; and a transformer balun that includes a single-ended winding, a first differential winding, and a second differential winding, wherein the single-ended winding is coupled to an antenna, the first differential winding is coupled to the low noise amplifier of the receiver section, and the second differential winding is coupled to the transmitter section, wherein loading of the transformer balun is substantially constant when the receiver section is enabled or when the transmit section is enabled.