Higher-order delta-sigma frequency-to-digital conversion

Techniques have recently been proposed for simultaneously performing angle-demodulation and A/D conversion that offer the potential of reduced circuit complexity over conventional approaches. The techniques give rise to systems that operate on the instantaneous frequency of an angle modulated input signal in the same manner that ΣΔ modulators operate on instantaneous amplitude. This paper presents various new structures that are analogous to higher-order ΔΣ modulators in terms of their quantization noise shaping capabilities. The tradeoffs associated with the higher-order systems are discussed, and simulations are presented