All-Digital CMOS Time-to-Digital Converter With Temperature-Measuring Capability

This brief presents an all-digital CMOS pulse-shrinking time-to-digital converter (TDC) with temperature-measuring capability for higher circuit value and cost saving. A pulse generator is proposed to generate either a time-added pulse or a temperature-sensing pulse. A cyclic delay line (DL) composed of a temperature-sensing DL and a pulse-shrinking DL becomes area efficient and achieves sufficiently wide dynamic range. A time subtractor that eliminates the effect of the offset error enhances accuracy. The proposed TDC is fabricated with TSMC 0.35-mu m CMOS process and has a small area of approximately 0.019 mm(2). The effective time resolution is approximately 45 ps, with an integral nonlinearity of -0.5 to 0.85 least significant bit (LSB). The achieved temperature resolution is nearly 0.1 degrees C/LSB, with an inaccuracy of -1.35 degrees C to 0.7 degrees C for a range of 0 degrees C-90 degrees C. Experimental results prove that we have proposed the first TDC that successfully measures time and temperature.