Semiconductor Die Diode Chains for Accurate On-Chip Temperature Sensing
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Solution Overview
Problem
Existing methods for temperature measurement in semiconductor dies are prone to inaccuracies due to parasitic resistive elements and may require additional active device area, which can be a challenge in high voltage or discrete power switch applications.
Innovation Solution
The use of two diode chains with different numbers of junctions or doping concentrations, connected in parallel, allows for a differential readout of temperature through the voltage difference between the chains, reducing the impact of parasitic resistive elements and minimizing the active device area required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single diode chain is used for temperature sensing, then the device area is minimized, but parasitic resistive elements reduce measurement accuracy
Solution Approach 1:
The temperature sensing function is segmented into two separate diode chains with different numbers of junctions (n1 and n2). Each chain independently responds to temperature, and their differential voltage output cancels out common-mode parasitic resistive effects while preserving temperature sensitivity. This segmentation allows accurate temperature measurement without requiring large compensation circuits.
Solution Approach 2:
The invention changes the parameter of junction number (n1 ≠ n2) between the two diode chains to create differential temperature sensitivity. By configuring chains with different junction counts, the system generates a voltage difference that is inherently proportional to temperature while rejecting parasitic resistance effects, achieving high precision without increasing device area.
2Measurement precision
If parasitic resistive elements are compensated using traditional methods, then measurement accuracy improves, but additional active device area is required
Solution Approach 1:
The invention extracts and eliminates the harmful effect of parasitic resistive elements through differential measurement. By subtracting the voltage outputs of two diode chains with different junction numbers, the common-mode parasitic resistances are automatically rejected, isolating only the temperature-dependent differential signal. This removes the need for separate compensation circuits that would consume additional area.
3Measurement precision
If bipolar transistors are used for temperature sensing, then temperature measurement is achieved, but integration complexity and material effort increase
Solution Approach 1:
The invention uses simplified diode chain structures that replicate the temperature sensing function of bipolar transistors without requiring complex bipolar device fabrication. By copying the essential pn-junction temperature response in a simpler diode configuration, the system achieves comparable temperature sensing capability with reduced integration complexity and material requirements.
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 improves the accuracy of temperature measurement by isolating the voltage difference due to junction properties, while also reducing the material and integration effort compared to using a single diode chain or a bipolar transistor.
Implementation Method 1
the different number and/or doping of the junctions results in a different forward voltage. The voltage difference between the diode chains will depend on the temperature
Data Source
AI summary
The disclosure relates to a semiconductor die, comprising: a first diode chain having a number n1 of diode junctions connected in series, where n1≥1; a second diode chain having a number n2 of diode junctions connected in series, where n2≥1; the first diode chain and the second diode chain to be biased with the same current as a temperature sensor, wherein the first diode chain and the second diode chain differ from each other in their respective number n1, n2 of junctions and/or in a doping concentration of at least one of the junctions.