Power-On Reset Circuit With Supply-Independent PTAT Current
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Solution Overview
Problem
Conventional power-on reset circuits face increased current issues as supply voltage scales up, leading to larger and more costly electronic systems due to the need for significant resistance values to compensate for this increase.
Innovation Solution
A power-on reset circuit incorporating a complementary-to-absolute-temperature (CTAT) circuit, a proportional-to-absolute-temperature (PTAT) circuit, and a comparator, which generates a power-on reset signal by comparing control voltages, ensuring the PTAT current is independent of the supply voltage, thus eliminating the need for current compensation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If supply voltage is scaled up, then power handling capability is improved, but current consumption increases
Solution Approach 1:
The patent changes the operating parameters by introducing PTAT and CTAT circuits that dynamically adjust the reset threshold voltage based on temperature. This allows the circuit to maintain proper reset functionality across different supply voltage levels without requiring proportional increases in current, thus resolving the contradiction between power handling capability and current consumption.
2Use of energy by moving object
If resistors of significant resistance values are used to compensate for increased current, then current control is improved, but circuit size and manufacturing cost increase
Solution Approach 1:
The patent replaces the mechanical/electrical approach of using large resistance values with a temperature-compensated voltage reference approach. By using PTAT and CTAT circuits to generate temperature-stable control voltages, the system achieves precise current control without requiring physically large resistors, thereby reducing circuit size and manufacturing cost while maintaining current control accuracy.
3Power
If supply voltage is scaled up, then operational power is improved, but reset circuit current increases requiring larger components
Solution Approach 1:
The patent changes the control parameter from fixed voltage threshold to temperature-compensated voltage threshold. The PTAT and CTAT circuits generate control voltages that account for temperature variations, allowing the reset circuit to operate correctly at higher supply voltages without requiring proportionally larger components. This parameter change enables high power operation with compact component sizes.
Data Source
AI summary
A power-on reset circuit includes a complementary-to-absolute-temperature circuit that outputs one control voltage, and a proportional-to-absolute-temperature (PTAT) circuit that outputs a PTAT current. The power-on reset circuit further includes various resistors that are coupled in series, and generate another control voltage based on the PTAT current that is outputted by the PTAT circuit. Further, the power-on reset circuit includes a comparator that compares the two control voltages to generate a power-on reset signal. The power-on reset signal is activated when a supply voltage is greater than or equal to a trip voltage, and deactivated when the supply voltage is less than the trip voltage. A functional circuit is configured to execute a reset operation associated therewith when the power-on reset signal transitions from a deactivated state to an activated state.