Thermal Sensor and Reference Circuits Based on a Time-Controlled Bias of pn-Junctions in FinFET Technology

This research introduces a new concept to generate PTAT and CTAT voltages precisely through switched-capacitor operation. In replacement of the classical BJT, the active bulk diode is utilized and forward-biased by a charge-pump. During capacitor discharge, the respective pn-junction voltages are sampled at different time points and further combined by charge-sharing techniques. A bandgap reference with this architecture shows an untrimmed accuracy of ±0.73% (3σ), consuming only 21 nA in a 16 nm FinFET process. Similarly, a thermal sensor was implemented with an 8-bit SAR readout, which achieves a precision of ≤2 °C without calibration on 2500 μm2 silicon area. The simple structures feature intrinsic supply rejection down to 0.85 V and a digital-alike operation.