Solid-State Pressure Sensor with On-Chip Offset Compensation
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Solution Overview
Problem
Conventional sensors for measuring parameters such as pressure suffer from inherent resistor and temperature offsets, require complex offset compensation circuits, and are susceptible to common mode noise due to long wires, increasing cost, size, and manufacturing complexity.
Innovation Solution
A sensor system utilizing MEMS circuitry with compensated ring clock multipliers that generate accurate higher speed clock signals, eliminating the need for additional circuits like differential amplifiers and ADCs, and using digital output to reduce noise susceptibility and simplify manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional piezoresistive sensors are used, then pressure measurement is achieved, but inherent resistor offset and temperature offset require complex compensation circuits
Solution Approach 1:
The patent extracts the offset compensation function from separate external circuits and integrates it directly into the sensor die structure. The first and second piezoresistive elements are formed as part of the integrated circuit, allowing the sensor to self-compensate for offsets without requiring external differential amplifiers or compensation circuits, thereby reducing overall device complexity while maintaining measurement precision
Solution Approach 2:
The patent merges the sensing function and offset compensation function into a single integrated circuit. The Wheatstone bridge configuration is implemented directly in the sensor die, combining the pressure measurement elements with the compensation elements in one unified structure, eliminating the need for separate compensation circuits and reducing system complexity
2Ease of operation
If long wires are used to couple sensor to electronic circuit, then signal transmission is achieved, but common mode noise is picked up
Solution Approach 1:
The patent extracts the signal transmission function from long external wires and implements it through short internal interconnects within the integrated circuit. The digital output is generated directly at the sensor location through on-chip logic circuits, eliminating the long wire pathway that would otherwise pick up common mode noise while maintaining signal transmission capability
Solution Approach 2:
The patent replaces the analog signal transmission mechanism (voltage signals over long wires) with a digital transmission mechanism (digital logic outputs). The sensor directly outputs digital signals through on-chip logic, eliminating the need for long analog signal transmission wires that act as antennas for common mode noise, thereby reducing noise susceptibility
3Measurement precision
If offset compensation circuits and differential amplifiers are added, then measurement accuracy is improved, but cost, size, and manufacturing complexity increase
Solution Approach 1:
The patent merges multiple functions (sensing, offset compensation, and signal conditioning) into a single integrated circuit manufactured using standard semiconductor fabrication processes. The Wheatstone bridge with compensation elements and digital output logic are all formed in one manufacturing step, eliminating the need for separate compensation circuits and reducing manufacturing complexity while maintaining accuracy
Solution Approach 2:
The patent implements self-service by incorporating self-compensating features directly in the sensor structure. The first and second piezoresistive elements are configured to automatically compensate for offset and temperature effects without requiring external compensation circuits, allowing the sensor to correct its own measurement errors internally
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system provides precise, noise-immune digital outputs, reduces manufacturing costs and complexity, and allows for flexible device design, particularly suitable for medical applications with space and power constraints.
Implementation Method 1
Wheatstone bridge sensors may include a piezoresistive circuit on a silicon-based die and may be configured as a pressure sensor or a strain gauge
Implementation Method 2
a first ring oscillator circuit oscillating at a first oscillation rate. The first oscillation rate may be based on a first set of physical parameters and a second physical parameter
Data Source
AI summary
Described herein are sensors for measuring various parameters. The sensors may be used in systems, devices, and methods for controlling blood flow or for measuring (e.g., monitoring) blood pressure, pH, or analyte levels such as a lactate level, an oxygen level, and/or a carbon dioxide level. The sensors may include a membrane configured to generate a measurable response (e.g., a change in an electrical signal such as resistance, capacitance, current, voltage) when the membrane interacts with a parameter of interest. In some instances, the sensors may include a piezoresistive MEMS subassembly. In other instances, the sensors may include an electrochemical membrane.