Abstract: A method and system is disclosed for designing a radio for down-converting RF signals to IF signals by sampling the signals in a round-robin sampling circuit and multiplying the samples by coefficients that are changed at a fixed rate equal to the rate of operation of each of the sampling circuits. The circuit is able to down-convert multiple channels simultaneously to adjacent positions in the IF band, while rejecting unwanted image signals. The method and system avoids the difficulty and cost of directly digitizing the RF signal, allowing each component to operate at a greatly reduced speed. The coefficients are selected to provide the desired transfer function while keeping the output signal centered at a desired frequency.

Abstract: The present application describes an apparatus and method for improving the performance of ?? modulators functioning as ADCs. In one embodiment, the ?? modulator comprises a plurality of quantizers operating in a round-robin fashion, rather than the single quantizer of the prior art. The use of multiple quantizers allows the ?? modulator to appear to be functioning at a significantly higher rate than a single quantizer allows. In another embodiment, a second-order ?? modulator contains a plurality of control loops, rather than the single control loop of the prior art. The use of multiple control loops allows the ?? modulator to have multiple points of maximum signal-to-noise ratio rather than a single such point as in prior art ?? modulators.