Abstract: A receiver with a balanced I/Q transformer is described. In an exemplary design, the receiver includes an LNA that amplifies a received RF signal and provides a single-ended RF signal to the balanced I/Q transformer. The balanced I/Q transformer includes at least one primary coil and first and second secondary coils. The first secondary coil is magnetically coupled to the at least one primary coil and provides a first differential RF signal to a first mixer. The second secondary coil is magnetically coupled to the at least one primary coil and provides a second differential RF signal to a second mixer. The first and second mixers downconvert the first and second differential RF signals with I and Q LO signals, respectively, and provide differential I and Q downconverted signals. The primary and secondary coils may be fabricated on two conductive layers of an integrated circuit.

Abstract: A tracking filter for attenuating out-of-band signals and adjacent channel signals in a receiver is described. In one exemplary design, an apparatus includes a tracking filter, an LNA, and a downconverter. The tracking filter includes a summer, a filter, and an upconverter. The summer subtracts a feedback signal from an input signal and provides a first signal. The LNA amplifies the first signal and provides a second signal. The downconverter frequency downconverts the second signal and provides an output signal. The filter filters (e.g., differentiates) the output signal and provides a third signal. The filter blocks a desired signal and passes out-of-band signal components. The upconverter frequency upconverts the third signal and provides a fourth signal from which the feedback signal is derived. The tracking filter has an equivalent bandpass filter response and a variable center frequency determined based on the frequency of the desired signal.

Abstract: A receiver with a balanced I/Q transformer is described. In an exemplary design, the receiver includes an LNA that amplifies a received RF signal and provides a single-ended RF signal to the balanced I/Q transformer. The balanced I/Q transformer includes at least one primary coil and first and second secondary coils. The first secondary coil is magnetically coupled to the at least one primary coil and provides a first differential RF signal to a first mixer. The second secondary coil is magnetically coupled to the at least one primary coil and provides a second differential RF signal to a second mixer. The first and second mixers downconvert the first and second differential RF signals with I and Q LO signals, respectively, and provide differential I and Q downconverted signals. The primary and secondary coils may be fabricated on two conductive layers of an integrated circuit.

Abstract: Method and apparatus for configuring a transmitter circuit to support linear or polar mode. In the linear mode, a baseband signal is specified by adjusting the amplitudes of in-phase (I) and quadrature (Q) signals, while in the polar mode, the information signal is specified by adjusting the phase of a local oscillator (LO) signal and the amplitude of either an I or a Q signal. In an exemplary embodiment, two mixers are provided for both linear and polar mode, with a set of switches selecting the appropriate input signals provided to one of the mixers based on whether the device is operating in linear or polar mode. In an exemplary embodiment, each mixer may be implemented using a scalable architecture that efficiently adjusts mixer size based on required transmit power.

Abstract: A tracking filter for attenuating out-of-band signals and adjacent channel signals in a receiver is described. In one exemplary design, an apparatus includes a tracking filter, an LNA, and a downconverter. The tracking filter includes a summer, a filter, and an upconverter. The summer subtracts a feedback signal from an input signal and provides a first signal. The LNA amplifies the first signal and provides a second signal. The downconverter frequency downconverts the second signal and provides an output signal. The filter filters (e.g., differentiates) the output signal and provides a third signal. The filter blocks a desired signal and passes out-of-band signal components. The upconverter frequency upconverts the third signal and provides a fourth signal from which the feedback signal is derived. The tracking filter has an equivalent bandpass filter response and a variable center frequency determined based on the frequency of the desired signal.

Abstract: Selectable sizes for a local oscillator (LO) buffer and mixer are disclosed. In an exemplary embodiment, LO buffer and/or mixer size may be increased when a receiver or transmitter operates in a high gain mode, while LO buffer and/or mixer size may be decreased when the receiver or transmitter operates in a low gain mode. In an exemplary embodiment, LO buffer and mixer sizes are increased and decreased in lock step. Circuit topologies and control schemes for specific exemplary embodiments of LO buffers and mixers having adjustable size are disclosed.