Multiple Event Time-to-Digital Conversion-Based Pulse Digitization for a 250 MHz Pulse Radio Ranging Application

A pulse digitizing approach for time-of-arrival pulse radio based ranging is introduced. It is based on a bank of time-to-digital converter (TDC) cores. A comparator bank triggers these multiple TDCs. This multiple event approach has advantages over classic single TDC solutions when facing unknown channel gains, noise corruption, and strong fading channel behavior. Pulses are digitized in a way that is superior in terms of performance versus power to classic A/D conversion. A power effort figure ξ and a new SNDR metric are introduced, easing performance comparison of pulse digitizers. A low power 8 channel digitizing system with a resolution of δt_ring=62.5 ps is presented for a cm accurate ranging application. The asynchronous, event-based nature of the architecture requires nonstrobed comparators to fire value crossing events. A dynamic range of 800:1 is realized. The digitization device is designed for 130 nm standard CMOS. An analog-baseband front-end I-Q energy detection and comparator threshold level configuration D/As are added to the design. The complete system is designed to consume 4 mW.