A Low Power ΔΣ Modulator with Low Voltage OTA for Wearable Applications

We present a low power ΔΣ modulator (DSM) with low voltage OTA for wearable applications. Wearable devices that monitor biological signals are powered by batteries. Therefore, the DSM in these devices must have low power consumption. One way to reduce the power consumption of DSM is to reduce the supply voltage. However, reducing the supply voltage leads to a reduction in the input voltage range of the OTA used in the modulator. To solve this problem, we propose an OTA that maintains a wide input voltage range even under a low supply voltage by using a bulk input. We also propose a low power DSM that can be operated under low voltage power supplies by using the proposed OTA. The proposed DSM is designed with a Rohm 0.18μm CMOS process with a supply voltage of 0.6 V. Circuit-level simulations show that the proposed modulator achieves a power consumption of 523 nW and a peak SNDR of 77.3 dB at 200 Hz bandwidth.