Programmable delay cell based area efficient time-mode smart temperature sensor exploiting channel length modulation coefficient λ

Abstract

This work presents an all-digital Programmable Delay Cell (PDC)-based time-domain smart temperature sensor exploiting the channel length modulation coefficient λ. For the first time the work has been described to establish the choice of multimode conversion options in the time-domain architecture of temperature sensor. The sensor incorporates a PDC and a time-to-digital converter (TDC) for the generation of temperature code. The different channel lengths of the PDC and Gated Ring Oscillator (GRO) delay elements of the TDC ensure the precise operation of the sensor. The proposed design provides a novel approach for the generation of variable resolution options having different sampling rates. At 90-nm CMOS process and 1.1 V supply voltage, the sensor occupies 0.015 mm2 and operates over a span of −60 °C to 120 °C. Additionally, multimode conversion time allows the sensor to be tuned to a small value of energy/conversion at 27 °C. This confirms to 0.38 nJ and 3.13 nJ at modes M0 and M7, respectively. Besides the sensor obtains a resolution 0.747 °C and 0.093 °C at a conversion time of 0.669 μs and 5.5 μs, respectively.