RF bandpass sigma-delta modulators

PARIS-BIUSJ-Mathématiques rech (751052111) / SudocSudocFranceF

A 1.3V 26mW 3.2GS/s Undersampled LC Bandpass Sigma-Delta ADC for a SDR ISM-band Receiver in 130nm CMOS

International audienceThis paper presents the implementation of an undersampled LC bandpass SigmaDelta ADC with a raised-cosine feedback DAC. It directly converts after the LNA a signal centered in the ISM band at 2.442 GHz with a sampling frequency of 3.256 GHz. This circuit has been fabricated in a 130 nm CMOS process, it occupies an area of 0.27 mm2 and is operating at a supply voltage of 1.3 V. The Signal-to-Noise and Distortion Ratios measured are 34 dB, 37dB and 42 dB for respective bandwidths of 25 MHz, 10 MHz and 1 MHz. The power consumption of the SigmaDelta ADC is 26 mW and its figure of merit is 2.3 pJ/bit

The Design of RF Bandpass Sigma-Delta Modulators with Bulk Acoustic Wave Resonators

International audienceThis paper proposes a method to introduce BAW resonators in the loop of a continuous-time sigma-delta modulator. The method is based on the equivalence between the noise-transfer-function of a conventional bandpass discrete-time sigma-delta and the noise-transfer-function of a continuous-time BAW-based sigma-delta modulator with FIRDACs. The method is general and can be applied to BAW resonators with and without cancellation of the anti-resonance frequency. The noise-transfer-function and the signal-transfer-function of the BAW-based sigma-delta modulator are analyzed and compared with their discrete-time counterpart