Semiconductor Temperature Sensor Circuit High Sensitivity Low Voltage
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Solution Overview
Problem
Prior temperature sensors face a trade-off between high sensitivity and flexible power supply operating values, as increasing sensitivity requires higher power supply voltages, while reducing stages for lower voltage compatibility results in reduced sensitivity.
Innovation Solution
A temperature sensor circuit with a current mirror and amplifier stages using P-N junctions with tailored resistances to produce temperature-sensitive and non-temperature-sensitive outputs, allowing for high sensitivity at lower power supply voltages and over wide temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If more P-N junction stages are added to increase sensitivity, then temperature sensitivity is improved, but power supply voltage requirement increases
Solution Approach 1:
The patent changes the operating parameters by using a single P-N junction with tailored resistance values rather than multiple junctions. By adjusting the resistance parameters in the circuit, the invention achieves high temperature sensitivity (e.g., -10 mV/C or higher) while operating at low power supply voltages (as low as 1.8V), thus resolving the contradiction between sensitivity and voltage requirement
Solution Approach 2:
The invention extracts and eliminates the unnecessary P-N junction stages from the traditional multi-junction architecture. By removing redundant junctions that only increase voltage requirements without providing proportional sensitivity benefits, the circuit achieves high sensitivity with minimal voltage headroom, directly addressing the technical contradiction
2Use of energy by moving object
If power supply voltage is reduced for low-power operation, then power consumption is improved, but temperature sensitivity is reduced
Solution Approach 1:
The patent optimizes the resistance parameters in the circuit to maximize temperature sensitivity at low supply voltages. By carefully selecting resistance values, the invention achieves high sensitivity coefficients (e.g., -10 mV/C or higher) even when operating at low power supply voltages (1.8V or lower), thus maintaining measurement precision while minimizing power consumption
Solution Approach 2:
The invention creates a dynamically optimized circuit where the resistance parameters are specifically tailored to operate in the low-voltage regime. The circuit is designed to be highly sensitive to temperature changes specifically in the low-power operating range, making the sensitivity adaptive to the reduced voltage conditions rather than simply degrading
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 solution achieves near-ideal performance with high sensitivity and flexible power supply operation, where the output voltage approaches the power supply voltage at low temperatures and approaches ground at high temperatures, even at low power supply voltages.
Implementation Method 1
The base-to-emitter voltage of these P-N junctions, Vbe(a)-(e), is a function of temperature, and essentially such voltage changes by about -2 mV per every degree Celsius
Data Source
AI summary
A temperature sensor circuit is disclosed. In one embodiment, the temperature sensor comprises an input circuit with a current mirror for forcing a current down a reference stage and an output stage. The reference stage and the output stage include P-N junctions (e.g., using bipolar transistors) with differing junction potentials. By tailoring the resistances in the reference and output stages, the input circuit produces two output voltages, one of which varies predictably with temperature, and one which is stable with temperature. The input circuit is preferably used in conjunction with an amplifier stage which preferably receives both the temperature-sensitive and non-temperature sensitive outputs. Through various resistor configurations in the amplifier stage, the output of the temperature sensor can be made to vary at a higher sensitivity than produced by the temperature-sensitive output of the input circuit. Moreover, as a result of the non-temperature-sensitive output, the output of the temperature sensor is additionally and beneficially tailored in its offset voltage in a temperature-independent manner. The result is a flexible circuit that can achieve very high sensitivities and near-ideal performance even at lower power supply voltages.