IC Junction Temperature Sensing Through ESD Diode Input Pins
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Solution Overview
Problem
Existing methods for monitoring and controlling the temperature of integrated circuits are limited by the accuracy and mobility of remote thermocouple probes, which can affect the reliability of temperature measurements and data quality during testing.
Innovation Solution
An apparatus and method that utilize existing pins and electrostatic discharge diodes within the integrated circuit to concurrently provide digital input signals and measure junction temperature, employing high and low side current sources, voltage sensors, and multiplexers to enable continuous temperature sensing and regulation without interfering with the system power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a remote thermocouple probe is used to monitor temperature, then temperature monitoring is possible, but measurement accuracy is limited by probe proximity to the junction
Solution Approach 1:
The ESD diode structure serves dual purposes: protecting the circuit from electrostatic discharge and functioning as an integrated temperature sensor. The diode's forward voltage naturally varies with junction temperature, eliminating the need for separate temperature sensing components and enabling self-measurement at the actual junction location.
Solution Approach 2:
The existing ESD diode, originally designed solely for electrostatic protection, is repurposed to also perform temperature sensing functions. This multi-functional approach allows the same hardware structure to provide both circuit protection and thermal monitoring without adding extra components.
2Ease of operation
If a physical thermocouple probe is used, then temperature can be monitored, but mobility and repositioning between devices is difficult
Solution Approach 1:
The integrated circuit itself provides the temperature sensing capability through its internal ESD diode, eliminating the need for external probes. The temperature is measured directly at the junction where it matters most, without requiring physical contact or repositioning of external sensors.
Solution Approach 2:
The temperature sensing function is extracted from the external probe and embedded within the integrated circuit's own structure. By utilizing the ESD diode's inherent temperature-dependent characteristics, the measurement is taken directly from the heat-generating junction rather than from a remote location.
3Measurement precision
If current is driven through the ESD diode for temperature sensing, then accurate junction temperature measurement is achieved, but interference with normal circuit operation must be avoided
Solution Approach 1:
Temperature measurement is performed using periodic current pulses through the ESD diode rather than continuous current. The pulsed measurement approach allows accurate temperature sensing while minimizing interference with normal circuit operation, as the diode is actively used only during brief measurement intervals.
Solution Approach 2:
The system dynamically switches the ESD diode between its normal protective function and temperature sensing function. During testing operations, the diode is used for temperature measurement; during normal operation, it returns to its electrostatic protection role, allowing adaptive use of the component based on system state.
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 allows for accurate and stable temperature control and measurement within the integrated circuit during testing, improving the reliability and usefulness of test data by maintaining a consistent temperature environment.
Implementation Method 1
sense a voltage drop across the diode structure... provides a sense signal that is indicative of the junction temperature in the IC
Data Source
AI summary
An apparatus measures a junction temperature in an IC through a pin of the IC and concurrently provides a digital input signal to digital logic of the IC through the pin. The IC has an ESD diode structure connected to the pin. High and low side voltage sensors sense a voltage drop across the diode structure. An input multiplexer controlled by the digital input signal selectively connects high and low side current sources to the pin to concurrently provide the digital input signal to the digital logic and to drive a constant current through the diode structure. An output multiplexer controlled by the digital input signal selectively connects the high and low side voltage sensors to an output that provides a sense signal indicative of the IC junction temperature.