A direct-conversion receiver integrated circuit for WCDMA mobile systems

A prototype of a 3-V SiGe direct-conversion receiver integrated circuit for use in third-generation (3G) WCDMA mobile cellular systems has been completed. The goal of its design was to minimize current draw while meeting WCDMA receiver rf specifications with margin. The design includes a bypassable low-noise amplifier, quadrature downconverter, and first-stage variable-gain baseband amplifiers integrated on chip. The design is optimized for use with a single-ended off-chip bandpass surface-acoustic-wave filter with no external matching components. The prototype design represents a first step toward a fully integrated monolithic WCDMA/UMTS receiver system-on-a-chip. A rigorous set of performance tests are used to characterize the noise and linearity performance of the packaged IC across its full frequency band of operation. A receiver test-bed system with a software baseband demodulator is used to determine the bit-error-rate performance of the receiver integrated circuit (IC) at sensitivity. Measured results are compared with estimated system performance requirements to determine compliance with key WCDMA rf specifications.