A CMOS PSR Enhancer with 87.3 mV PVT-Insensitive Dropout Voltage for Sensor Circuits.

Jianyu Zhang,Pak Kwong Chan

doi:10.3390/s21237856

Abstract

A new power supply rejection (PSR) based enhancer with small and stable dropout voltage is presented in this work. It is implemented using TSMC-40 nm process technology and powered by 1.2 V supply voltage. A number of circuit techniques are proposed in this work. These include the temperature compensation for Level-Shifted Flipped Voltage Follower (LSFVF) and the Complementary-To-Absolute Temperature (CTAT) current reference. The typical output voltage and dropout voltage of the enhancer is 1.1127 V and 87.3 mV, respectively. The Monte-Carlo simulation of this output voltage yields a mean T.C. of 29.4 ppm/°C from −20 °C and 80 °C. Besides, the dropout voltage has been verified with good immunity against Process, Temperature and Process (PVT) variation through the worst-case simulation. Consuming only 4.75 μA, the circuit can drive load up to 500 μA to yield additional PSR improvement of 36 dB and 20 dB of PSR at 1 Hz and 1 MHz, respectively for the sensor circuit of interest. This is demonstrated through the application of an enhancer on the instrumentation Differential Difference Amplifier (DDA) for sensing floating bridge sensor signal. The comparative Monte-Carlo simulation results on a respective DDA circuit have revealed that the process sensitivity of output voltage of this work has achieved 14 times reduction in transient metrics with respect to that of the conventional counterpart over the operation temperature range in typical operation condition. Due to simplicity without voltage reference and operational amplifier(s), low power and small consumption of supply voltage headroom, the proposed work is very useful for supply noise sensitive analog or sensor circuit applications.

Highlights

With the continuous advancement of integrated circuit design and manufacturing technology, sensor circuits and systems tend to be integrated together on one single chip.For analog circuits, especially sensor circuits, a high-quality supply source is often needed to maintain their function and accuracy
Due to simplicity without voltage reference and operational amplifier(s), low power and small consumption of supply voltage headroom, the proposed work is very useful for supply noise sensitive analog or sensor circuit applications
Specific circuit methods can be employed to improve the performance of sensor circuits arising from the reduced supply sensitivity in VCO based sensor [1] and reduced supply noise in image sensor [2], these methods are only applicable for the limited case examples

Summary

Introduction

With the continuous advancement of integrated circuit design and manufacturing technology, sensor circuits and systems tend to be integrated together on one single chip.For analog circuits, especially sensor circuits, a high-quality supply source is often needed to maintain their function and accuracy. In order to increase power supply rejection (PSR), the sensor circuit employing the feedback design [3,4] to the bridge sensing elements is a popular method. It relies on splitting a full bridge sensing element into two half bridge sensors. Regarding recent trend towards low-power consumption, one of the Sensors 2021, 21, 7856 dressed the importance of supply issues based on the impact of supply sensitivity or supply noise on the sensor circuit performance. Regarding recent trend towards low-power consumption, one of the previously reported supply circuits [9] can consume low power

Methods

Results

Conclusion