A No-Trim, Scaling-Friendly Thermal Sensor in 16nm FinFET Using Bulk Diodes as Sensing Elements

We present a simple, yet robust architecture to achieve accurate temperature sensing without the need for costly calibration. For the first time, the active bulk diode of a standard CMOS process is utilized in replacement of BJT devices. Two such diodes are forward biased by a charge pump, which periodically discharges two sampling capacitors across the diodes. The sampled voltages are then combined to generate PTAT and CTAT signals. A passive charge-balancing scheme creates a digital output, which only requires a comparator, an 8-bit capacitive divider and SAR logic. Occupying 2500 μm
²
active area in 16-nm FinFET, the sensor operates down to 0.85 V and features intrinsic supply robustness. It achieves an uncalibrated accuracy of +1.5/-2.0 °C (min/max) across the consumer temperature range, and dissipates 230 pJ in a 12.8 μs conversion time. Due to the simplicity and low analog content of this concept, it is insensitive to future scaling and well suited for use at multiple locations in SoCs.