A cellular radio architecture that includes a programmable bandpass sampling radio frequency front-end and an optimized digital baseband. The architecture includes a multiplexer having signal paths that include a bandpass filter that passes a different frequency band than the other bandpass filters and a circulator that provides signal isolation between the transmit signals and the receive signals. The architecture also includes a receiver module having a separate signal channel for each of the signal paths in the multiplexer, where each signal channel in the receiver module includes a receiver delta-sigma modulator that converts analog receive signals to a representative digital signal. The architecture further includes a transmitter module having a transmitter delta-sigma modulator for converting digital data bits to analog transmit signals, where the transmitter module includes a power amplifier and a switch for directing the transmit signals to one of the signal paths in the multiplexer.

An RF transmitter module for a cellular radio that includes a delta-sigma modulator having a plurality of interleaving dynamic element matching (DEM) circuits providing interleaved digital bits at a reduced clock rate. An interleaver controller controls the DEM circuits so as to provide groups of the digital bits at different points in time. In one embodiment, a summation junction adds the groups of the digital bits to provide a continuous stream of the interleaved digital bits, a DAC converts the stream of interleaved digital bits to an analog signal, and a power amplifier amplifies the analog signal.

A continuous-time bandpass Sigma-Delta modulator includes a transconductance operational amplifier, a passive resonator, a sampling quantizer, a current feedback module, and a voltage feedback module. The transconductance operational amplifier receives an input voltage signal and convert it to output a current signal. The passive resonator is connected to an output end of the transconductance operational amplifier as a loop filter and converts the current signal to output an intermediate voltage signal. The sampling quantizer is connected to an output end of the passive resonator and samples and quantizes the intermediate voltage signal to output a thermometer code. The current feedback module and the voltage feedback module both are connected to the sampling quantizer and the passive resonator, and respectively provide a feedback current and a feedback voltage for the passive resonator under control of the thermometer code.