{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:28:49Z","timestamp":1760243329923,"version":"build-2065373602"},"reference-count":22,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2014,10,10]],"date-time":"2014-10-10T00:00:00Z","timestamp":1412899200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004663","name":"Ministry of Science and Technology of Taiwan","doi-asserted-by":"publisher","award":["MOST 103-2220-E-224-002","MOST 103-2221-E-327-047"],"award-info":[{"award-number":["MOST 103-2220-E-224-002","MOST 103-2221-E-327-047"]}],"id":[{"id":"10.13039\/501100004663","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This study proposes a linearity-enhanced time-domain complementary metal-oxide semiconductor (CMOS) thermostat with process-variation calibration for improving the accuracy, expanding the operating temperature range, and reducing test costs. For sensing temperatures in the time domain, the large characteristic curve of a CMOS inverter markedly affects the accuracy, particularly when the operating temperature range is increased. To enhance the on-chip linearity, this study proposes a novel temperature-sensing cell comprising a simple buffer and a buffer with a thermal-compensation circuit to achieve a linearised delay. Thus, a linearity-enhanced oscillator consisting of these cells can generate an oscillation period with high linearity. To achieve one-point calibration support, an adjustable-gain time stretcher and calibration circuit were adopted for the process-variation calibration. The programmable temperature set point was determined using a reference clock and a second (identical) adjustable-gain time stretcher. A delay-time comparator with a built-in customised hysteresis circuit was used to perform a time comparison to obtain an appropriate response. Based on the proposed design, a thermostat with a small area of 0.067 mm2 was fabricated using a TSMC 0.35-\u03bcm 2P4M CMOS process, and a robust resolution of 0.05 \u00b0C and dissipation of 25 \u03bcW were achieved at a sample rate of  10 samples\/s. An inaccuracy of \u22120.35 \u00b0C to 1.35 \u00b0C was achieved after one-point calibration at temperatures ranging from \u221240 \u00b0C to 120 \u00b0C. Compared with existing thermostats, the proposed thermostat substantially improves the circuit area, accuracy, operating temperature range, and test costs.<\/jats:p>","DOI":"10.3390\/s141018784","type":"journal-article","created":{"date-parts":[[2014,10,10]],"date-time":"2014-10-10T10:24:07Z","timestamp":1412936647000},"page":"18784-18799","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["A Linearity-Enhanced Time-Domain CMOS Thermostat with Process-Variation Calibration"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6354-0280","authenticated-orcid":false,"given":"Chun-Chi","family":"Chen","sequence":"first","affiliation":[{"name":"Department of Electronic Engineering, National Kaohsiung First University of Science and Technology, Kaohsiung 811, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yi","family":"Lin","sequence":"additional","affiliation":[{"name":"Department of Electronic Engineering, National Kaohsiung First University of Science and Technology, Kaohsiung 811, Taiwan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2014,10,10]]},"reference":[{"key":"ref_1","first-page":"1908","article-title":"A Temperature Sensor with Single Resistor Set-Point Programming","volume":"34","author":"Brokaw","year":"1999","journal-title":"IEEE J. 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