Study of SAW resonator based band pass delta-sigma modulators

Abstract

The superheterodyne receiver with a band pass analog to digital converter (ADC) architecture promises a reduction in size and power consumption in conventional radio frequency receivers. To realize this architecture, a band pass ADC that operates at high frequencies with high selectivity is needed. This thesis explores the possibility of employing surface acoustic wave (SAW) resonators in delta- sigma modulators. It promises digitization of signals with high selectivity at high frequencies. A fourth order band pass continuous time delta-sigma modulator employing SAW resonators was designed and implemented. The anti-resonance cancellation circuit and multi-feedback architecture were used in the modulator. The modulator was fabricated in 0.8um BYR technology. The modulator was found to be highly sensitive to small changes in capacitance in the anti-resonance cancellation circuit. Future work could look into making the anti-resonance cancellation circuit more robust.