Differential TMR Sensor Readout Circuit for Harmonic Suppression
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Solution Overview
Problem
Existing tunneling magnetoresistance sensors face issues with harmonic distortion in their reading circuits, leading to compromised linearity and low data reading accuracy, limiting their application in high-precision systems like inertial navigation and positioning.
Innovation Solution
A harmonic suppression circuit for tunneling magnetoresistance sensors is designed with a fully differential interface circuit topological structure, virtual geminate transistor parallel structure, and complementary switch structure to restrain even-order harmonic distortion, charge injection, and clock feedthrough effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing reading circuits are used for tunneling magnetoresistance sensors, then the sensors can be manufactured with small size, low cost and low power, but harmonic distortion occurs leading to compromised linearity and low data reading accuracy
Solution Approach 1:
The reading circuit is divided into multiple differential stages (chopping instrumentation amplifier and sigma-delta modulator) with each stage processing signals differentially to cancel even-order harmonics. The segmentation of functions across multiple specialized circuits allows systematic suppression of harmonic distortion while maintaining the sensor's small size and low power advantages.
Solution Approach 2:
The patent employs asymmetric transistor pairing (virtual geminate transistors) where transistors are designed to have complementary but not identical characteristics. This controlled asymmetry, when combined with differential signaling, allows the circuit to cancel even-order harmonic distortion while maintaining signal integrity and high linearity for accurate data reading.
2Reliability
If high-precision applications like inertial navigation are required, then strict requirements for harmonic distortion must be met, but existing tunneling magnetoresistance sensors have limited application due to harmonic distortion in reading circuits
Solution Approach 1:
The sigma-delta modulator incorporates feedback mechanisms that continuously monitor and correct for harmonic distortion in real-time. The feedback loop adjusts circuit parameters dynamically to maintain high linearity and suppress even-order harmonics, ensuring reliable performance evaluation and meeting strict requirements for high-precision applications like inertial navigation systems.
Solution Approach 2:
The chopping instrumentation amplifier uses periodic switching at a specific chopping frequency to modulate the input signal. This periodic action, when synchronized with the signal processing stages, allows even-order harmonic distortion to be shifted to frequencies where it can be easily filtered out, thereby improving reliability for high-precision applications.
3Stability of the object's composition
If a fully differential interface circuit topological structure is used, then even-order harmonic distortion is restrained and linearity is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into the fully differential circuit structure: signal amplification, harmonic suppression, and noise rejection are all achieved within the same differential topology. By combining these functions rather than adding separate circuits, the patent improves linearity and stability while limiting the increase in overall device complexity.
Solution Approach 2:
The fully differential structure is applied locally at critical stages where harmonic distortion has the greatest impact (input amplification and signal conditioning), rather than throughout the entire system. This targeted application of differential topology provides maximum linearity improvement with minimal additional complexity in non-critical circuit areas.
Data Source
AI summary
Disclosed is a harmonic suppression circuit for tunneling magnetoresistance sensors, which restrains even-order harmonic distortion by means of a fully differential interface circuit topological structure, restrains the charge injection and clock feedthrough effect of transistors by means of a virtual geminate transistor parallel structure and reduces the on resistance by means of a complementary switch structure to effectively restrain harmonic distortion. The harmonic suppression circuit for tunneling magnetoresistance sensors has a high linearity and has a high reading accuracy when used for reading sensing data of tunneling magnetoresistance sensors.