Design of tunable continuous-time quadrature bandpass delta-sigma modulators

This paper presents a systematic design technique for a tunable continuous-time quadrature bandpass delta-sigma modulator. The tuning range of the modulator covers from 0.05 to 0.45 of the sampling frequency. The design procedure is applied to the design of a second-order modulator. Results show that the Signal-to-Noise Ratio (SNR) is almost constant and no stability problem occurs over the whole tuning range thanks to a Digital-to-Analog Converter (DAC) compensation scheme.