CMOS Temperature Sensor with Back-Gate Bias for Low Power Operation
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Solution Overview
Problem
Conventional bipolar junction transistor (BJT)-based temperature sensors face challenges in operating at low power voltage levels, such as 1V or sub-1V, due to larger voltage-base-to-emitter requirements and significant parasitic variations in deep-submicron process technologies, which limits their ability to accurately sense a wide range of temperatures.
Innovation Solution
The implementation of temperature sensors with back-gate bias control using complementary-metal-oxide-semiconductor (CMOS) devices in fully-depleted-silicon-on-insulator (FD SOI) technologies, incorporating a voltage-gate-source generator, Ibias generator, back-gate bias generator, and temperature read-out circuit, along with resistor trimming codes for calibration, to reduce offset and slope variations and enable accurate temperature sensing at low power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If BJT-based temperature sensors are used for high precision sensing, then measurement precision is improved, but power consumption increases due to larger voltage requirements
Solution Approach 1:
The patent changes the operating parameters of the temperature sensor by using CMOS transistors with back-gate bias control instead of BJT devices. This allows the sensor to operate at lower voltage levels (sub-1V) while maintaining temperature sensing functionality. The back-gate bias voltage is adjusted to optimize the transistor's threshold voltage and transconductance, enabling precise temperature measurement at reduced power consumption.
Solution Approach 2:
The back-gate bias voltage serves as an intermediary control mechanism that enables the CMOS transistor to operate in the appropriate region for temperature sensing. By controlling the back-gate voltage, the sensor can achieve the necessary sensitivity and precision typically associated with BJT devices, but with lower power requirements.
2Measurement precision
If BJT-based temperature sensors are used for accurate temperature sensing, then measurement precision is improved, but device complexity increases due to additional mask layers needed for control
Solution Approach 1:
The patent uses standard CMOS transistor structures that are already well-established in deep-submicron process technologies. Instead of requiring specialized BJT devices with additional mask layers, the invention replicates the temperature sensing functionality using conventional CMOS processes, thereby reducing manufacturing complexity while maintaining sensing precision.
3Productivity
If BJT-based temperature sensors are used in deep-submicron processes, then integration is improved, but measurement precision deteriorates due to significant parasitic variations
Solution Approach 1:
The back-gate bias control mechanism provides a feedback path that compensates for parasitic variations in the CMOS transistors. By adjusting the back-gate voltage, the sensor can compensate for process variations and maintain accurate temperature measurements, overcoming the parasitic issues that plague BJT-based sensors in deep-submicron processes.
Data Source
AI summary
Temperature sensors for integrated circuits that use back-gate bias for low power operation. A temperature sensor can comprise a voltage-gate-source generator having sensing transistors; an Ibias generator; a back-gate bias generator; and a temperature read-out circuit. In a calibration mode, the temperature sensor determines a back-gate bias voltage and a resistor trimming code to be used during functional operation.