A Temperature-to-Digital Converter Based on an Optimized Electrothermal Filter

作者：Kashmiri S Mahdi^*; Xia Sha; Makinwa Kofi A A

来源：IEEE Journal of Solid-State Circuits, 2009, 44(7): 2026-2035.

DOI：10.1109/JSSC.2009.2020248

• Electrothermal filters
• phase-domain sigma-delta modulator
• synchronous demodulation
• temperature sensors

This paper describes the design of a CMOS temperature-to-digital converter (TDC). It operates by measuring the temperature-dependent phase shift of an electrothermal filter (ETF). Compared to previous work, this TDC employs an ETF whose layout has been optimized to minimize the thermal phase spread caused by lithographic inaccuracy. To minimize electrical phase spread, the TDC's front-end consists of a wide bandwidth gain-boosted transconductor. The transconductor's output current is then digitized by a phase-domain Sigma Delta modulator whose phase-summing node is realized by a chopper demodulator. To minimize the residual offset caused by the demodulator's switching action, the demodulator is located at the virtual ground nodes established by the transconductor's gain-boosting amplifiers. Measurements on 16 samples (within one batch) show that the TDC has an untrimmed inaccuracy of less than +/- 0.7 degrees C (3 sigma) over the military range (-55 degrees C to 125 degrees C).

• 出版日期2009-7