A GSM demodulator based on a delta-sigma frequency discriminator with improved input sensitivity

A GSM receiver based on a ΔΣ frequency discriminator with enhanced input sensitivity is presented. The ΔΣ frequency discriminator architecture in this paper allows the effective frequency deviation to be increased thus utilizing a larger portion of the available dynamic range. This permits the demodulation of small-deviation FM signals while retaining a relatively high sampling rate. The new architecture is shown to be suitable for non-coherent demodulation of narrow band, continuous-phase FSK signals. The frequency discriminator is realized in a 0.8µm BiCMOS process and consumes 75mW with a 3V supply and covers an area of 9mm².