Techniques for designing baseband processing circuitry for radio IC's. In an aspect, techniques for differential-to-single-ended conversion in a baseband portion of the IC are disclosed to reduce the pin count and package size for RF IC's. In another aspect, the converter includes selectable narrowband and wideband amplifiers, wherein the wideband amplifiers may be implemented using transistor devices having smaller area than corresponding transistor devices of narrowband amplifiers. Further techniques for bypassing one or more elements, and for implementing a low-pass filter of the converter using an R-C filter network, are described.