Abstract
Resistive bridge sensors are used in many application areas to measure changes in physical parameters. To amplify the resistive changes from sensing elements with high precision, various offset contributors in the resistive bridge and amplifiers should be minimized. This study proposes a low-noise resistive bridge sensor analog front-end (AFE) using a chopper-stabilized multipath current feedback instrumentation amplifier (CFIA) and an automatic offset cancellation loop. The proposed circuit exploits a multipath chopper-stabilized architecture for obtaining low noise performance and wide bandwidth characteristics. This circuit can minimize the offsets in the bridge and the high frequency and low frequency amplifiers, while achieving high precision resistive signal acquisition. The high frequency path of the multipath amplifier uses the CFIA topology with class-AB output stage. The offset in the high frequency path is stabilized by the low frequency path amplifier with a high gain and low noise chopper amplifier. The up-modulated offset in the low frequency chopper amplifier path is reduced by the AC-coupled ripple reduction loop (RRL). An automatic offset calibration loop (AOCL) circuit was designed to calibrate the offset due to the bridge mismatch. The AOCL reduces the bridge offset using a successive approximation register (SAR)-based binary-search algorithm. The gain of the proposed circuit is adjustable from 15.56 dB to 44.14 dB. The AFE is implemented in a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.18~ \boldsymbol {\mu } \text{m}$ </tex-math></inline-formula> CMOS process and draws <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$123~ \boldsymbol {\mu } \text{A}$ </tex-math></inline-formula> current from a 3.3 V supply. The input referred noise and noise efficiency factor (NEF) are 14.6 nV/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\surd } $ </tex-math></inline-formula> Hz and 6.1, respectively.
Highlights
Resistive microelectromechanical system (MEMS) sensors are in the spotlight for detecting various environmentalThe associate editor coordinating the review of this manuscript and approving it for publication was Venkata Rajesh Pamula .changes such as force, acceleration, pressure, and humidity owing to their advantages such as reliability and low price based on their simple structure and long-lasting durability [1]–[5]
The MEMS sensors suffer from the severe process variations, and these process variations are getting worse because the process variations are inversely proportional to the square-root of the area [7]
The offset of the main path is stabilized by the low noise and high gain auxiliary amplifier with various dynamic offset cancellation (DOC) techniques
Summary
Resistive microelectromechanical system (MEMS) sensors are in the spotlight for detecting various environmentalThe associate editor coordinating the review of this manuscript and approving it for publication was Venkata Rajesh Pamula .changes such as force, acceleration, pressure, and humidity owing to their advantages such as reliability and low price based on their simple structure and long-lasting durability [1]–[5]. INDEX TERMS Resistive analog front-end, current feedback instrumentation amplifier (CFIA), multipath amplifier, automatic offset calibration loop (AOCL). M. Yoo et al.: Low-Noise Resistive Bridge Sensor AFE Using Chopper-Stabilized Multipath CFIA and AOCL The CFIA is widely used in resistive bridge sensors because it can achieve a high input impedance, low noise, and low power characteristics [18], [19].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
