Bandgap Thermal Sensor Circuit Area Reduction
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Solution Overview
Problem
Conventional thermal shutdown circuits in integrated circuits require significant silicon area and power, and involve separate trimming operations, which increase manufacturing costs and resource consumption.
Innovation Solution
A thermal sensor circuit that utilizes temperature dependent and independent voltages tapped from existing bandgap reference circuitry, with a comparator to generate a digital output signal, minimizing additional silicon area and power usage, and automatically trimming during bandgap reference voltage trimming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional thermal shutdown circuit is implemented separately from the bandgap reference circuit, then thermal shutdown functionality is provided, but silicon area and power consumption increase significantly
Solution Approach 1:
The patent combines the thermal shutdown circuit with the bandgap reference circuit by sharing common components (operational amplifier, resistors, diodes) between the two functions. The thermal shutdown comparator uses the same operational amplifier and resistor network as the bandgap reference circuit, eliminating the need for separate dedicated thermal sensing components and reducing overall silicon area.
Solution Approach 2:
The bandgap reference circuit components serve multiple functions: generating the temperature-independent reference voltage and providing temperature-dependent voltages for thermal shutdown detection. The operational amplifier and resistor network simultaneously perform bandgap voltage generation and thermal sensing, making the circuit multi-functional and reducing component count.
2Reliability
If a conventional thermal shutdown circuit is implemented separately, then thermal shutdown functionality is provided, but power consumption increases
Solution Approach 1:
The thermal shutdown circuit shares the operational amplifier and resistor network with the bandgap reference circuit, eliminating duplicate power-consuming components. The same operational amplifier performs both bandgap voltage generation and thermal shutdown comparison functions, reducing overall power consumption.
Solution Approach 2:
The bandgap reference circuit components serve dual purposes: generating the reference voltage and enabling thermal shutdown detection. This multi-functionality reduces the total power consumption by avoiding separate dedicated thermal sensing circuitry that would consume additional power.
3Manufacturing precision
If separate trimming operations are performed for bandgap reference and thermal sensor, then accurate voltage reference and thermal sensing are achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the trimming operations for both bandgap reference and thermal sensor into a single unified trimming process. By sharing common components and using a unified trimming mechanism, only one trimming operation is needed to accurately calibrate both functions, reducing manufacturing complexity.
Solution Approach 2:
The trimming mechanism serves both the bandgap reference voltage calibration and the thermal sensor calibration simultaneously. This unified approach allows a single trimming operation to achieve accurate voltage reference and thermal sensing, eliminating the need for separate trimming processes.
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
This approach reduces silicon area and power consumption while simplifying trimming operations, providing an accurate thermal shutdown signal with reduced manufacturing costs by leveraging existing bandgap reference circuitry.
Implementation Method 1
a thermal sensor that compares a temperature dependent voltage to a temperature independent voltage, both temperatures being referenced to a bandgap reference voltage
Implementation Method 2
bandgap reference circuits function as temperature independent voltage reference circuits to provide a bandgap reference voltage Vbg at a voltage level typically around 1.25 V, which is close to the theoretical 1.22 eV bandgap of silicon at 0° K
Data Source
AI summary
A thermal sensor for an integrated circuit including a bandgap reference circuit. The thermal sensor includes a comparator that compares a temperature dependent voltage generated by the bandgap reference circuit to a temperature independent voltage, where both temperatures are referenced to the bandgap reference voltage generated by the bandgap reference circuit. The thermal sensor generates a digital output control signal based on a predetermined relationship between the temperature dependent voltage and the temperature independent reference voltage. When used as a thermal shutdown circuit, the comparator generates a thermal shut-down signal when the dependent temperature voltage decreases (or increases) with rising system temperature to equal to the temperature independent reference voltage. The comparator is implemented using an operational amplifier that is connected to existing circuitry associated with the bandgap reference circuit.