This paper presents a 1.2 V high accuracy thermal sensor analog front-end circuit with 7 probes placed around the microprocessor chip. This analog front-end consists of a BGR (bandgap reference), a DEM (dynamic element matching) control, and probes. The BGR generates the voltages linear changed with temperature, which are followed by the data read out circuits. The superior accuracy of the BGR’s output voltage is a key factor for sensors fabricated via the FinFET digital process. Here, a 4-stage folded current bias structure is proposed, to increase DC accuracy and confer immunity against FinFET process variation due to limited device length and low current bias. At the same time, DEM is also adopted, so as to filter out current branch mismatches. Having been fabricated via a 12 nm FinFET CMOS process, 200 chips were tested. The measurement results demonstrate that these analog front-end circuits can work steadily below 1.2 V, and a less than 3.1% 3σ-accuracy level is achieved. Temperature stability is 0.088 mV/C across a range from –40 to 130 C.

本文介绍了一个 1.2 V 高精度热传感器模拟前端电路，在微处理器芯片周围放置了 7 个探针。该模拟前端由 BGR（带隙参考）、DEM（动态元素匹配）控制和探头组成。BGR 产生随温度线性变化的电压，然后是数据读出电路。BGR 输出电压的卓越精度是通过 FinFET 数字工艺制造的传感器的关键因素。在这里，提出了 4 级折叠电流偏置结构，以提高 DC 精度并增强对 FinFET 工艺变化的免疫力，因为有限的器件长度和低电流偏置。同时，也采用了DEM，过滤掉当前的支路失配。通过 12 纳米 FinFET CMOS 工艺制造，测试了 200 个芯片。测量结果表明，这些模拟前端电路可以在低于 1.2 V 的电压下稳定工作，并且达到了小于 3.1% 的 3σ-精度水平。在 –40 至 130 C 的范围内，温度稳定性为 0.088 mV/C。