A 12-bit low-power multi-channel ramp ADC using digital DLL techniques for high-energy physics and biomedical imaging

Abstract

This paper presents the design of a low-power multi-channel time-based analog-to-digital converter (ADC) for the instruments dedicated to high-energy physic experiments and biomedical imaging applications. The proposed ADC is realized by using two-step conversion scheme: the voltage-to-time conversion (VTC) and the digital-to-time conversion (TDC). In VTC, the classic Wilkinson-type architecture are adopted. Both the high-precise ramp generator and the high-resolution high-speed comparator are presented. In TDC, counter-based circuits and the time interpolation based on a digital delay-locked loop (DLL) are proposed. A eight-channel prototype has been designed in AMS 0.35 #m technology. The typical resolution of the ADC is 12 bits. The typical sampling rate is about 1 Msample/s while the clock is 100 MHz. The power dissipation is 3 mW + 0.8 mW/channel. This is the first report on the design of a time-based ADC using digital DLL with low power, multiple channels and high resolution for the application of particle detections.