5 x 5 scattered temperature sensor front-end based on single-doide with non-trimmed ±0.7°C 3σ relative inaccuracy

A bipolar junction transistor (BJT)-based scattered relative temperature sensor front-end with a 5 x 5 remote sensor node array in 180 nm CMOS process is presented. To eliminate diode mismatches and reduce the sensor node area, a single-diode approach that accurately switches different amounts of currents into a single PNP BJT is employed. Dynamic element matching (DEM) is applied to the current mirrors so that the current ratio is precisely controlled. The 5 x 5 sensor nodes with a unit size of only 15 x 10 mu m(2) are distributed across the chip. Experimental results show that the minimum supply voltage (analogue) is 1 V over a temperature range of 0-125 degrees C. The measured 3 sigma relative inaccuracy was <+/- 0.7 degrees C without trimming across the 0-125 degrees C temperature range while drawing a current of <22 mu A. Furthermore, the multi-location thermal monitoring function has been demonstrated experimentally and a 4 degrees C/mm on-chip temperature gradient was detected.