A 10MHz CTDSM with differential VCO-based quantizer in 90nm

This paper presents a new architecture for VCO-based Continuous Time Delta Sigma Modulators. This approach is based on the differential configuration for the quantizer while maintains its inherent dynamic element matching property. Consuming no additional power and area compared to the conventional scheme, this architecture can eliminate the even orders of harmonic distortion and achieve higher linearity. Theoretical analysis for signal to quantization noise, power and area consumption and mismatch effect is provided. To illustrate the effectiveness of the new architecture in continuous time modulators, a modulator with 640 MHz sampling rate utilizing the mentioned quantizer is simulated in 90nm technology. Obtaining linearity enhancement compared to the conventional design, the modulator achieves the maximum SNDR of 72dB over a 10 MHz bandwidth. The modulator consumes 56.9 mW from a 1.2 V supply.