Substrate Bias Control Using Source-Potential Leakage Detection
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Solution Overview
Problem
Existing semiconductor integrated circuit technologies face limitations in detecting leakage current fluctuations, particularly at low power supply voltages, due to limitations in detecting drain potential changes and circuit design restrictions, as well as DC offset errors from comparator usage.
Innovation Solution
A semiconductor integrated circuit apparatus with a substrate voltage control block that adjusts substrate voltage based on comparator feedback, using a leakage current detection circuit with MIS transistors connected to constant current sources and stabilizing potentials, and incorporating a switch to correct DC offset by averaging reference voltage settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power supply voltage is lowered to reduce power consumption, then power consumption decreases, but threshold voltage fluctuations of MIS transistors increase and substantially influence operating speed
Solution Approach 1:
The patent changes the parameter being controlled from drain potential to source potential of the detection transistor. By detecting source potential changes instead of drain potential changes, the system can effectively monitor leakage current fluctuations even at low power supply voltages, thereby maintaining operating speed stability while allowing reduced power consumption.
Solution Approach 2:
The patent implements a feedback mechanism where the detected source potential is compared with a reference potential, and the substrate bias is adjusted based on the comparison result. This feedback loop compensates for threshold voltage fluctuations caused by low power supply voltage, ensuring stable operating speed while maintaining low power consumption operation.
2Measurement precision
If drain potential of leakage current detection transistor is used for detection, then leakage current can be detected, but detection sensitivity is insufficient at low power supply voltages due to limited drain potential changes
Solution Approach 1:
The patent inverts the conventional detection approach by detecting source potential changes instead of drain potential changes. This inversion allows the detection system to achieve sufficient sensitivity at low power supply voltages, as source potential changes provide a more reliable indication of leakage current variations under low-voltage conditions.
Solution Approach 2:
The patent changes the detection parameter from drain potential to source potential. This parameter change enables effective leakage current detection at low power supply voltages, as the source potential exhibits sufficient variation to indicate leakage current changes even when drain potential changes are minimal.
3Reliability
If comparator is used for substrate voltage control, then substrate voltage can be regulated, but DC offset errors from comparator reduce control precision
Solution Approach 1:
The patent applies preliminary action by adjusting the reference potential to compensate for comparator DC offset errors before the actual substrate voltage control operation. This preliminary calibration ensures that the comparator operates accurately throughout the control range, maintaining both reliable substrate voltage regulation and high control precision.
Solution Approach 2:
The patent changes the reference potential parameter to account for and compensate for comparator DC offset errors. By dynamically adjusting the reference potential based on the detected offset, the system maintains precise substrate voltage control despite the inherent limitations of comparator-based regulation.
4Reliability
If conventional substrate bias circuit is used to correct threshold voltage, then threshold voltage can be controlled, but circuit design restrictions and complexity increase
Solution Approach 1:
The patent makes the detection transistor serve multiple functions: it detects leakage current by monitoring source potential changes, and its source potential serves as the feedback signal for substrate bias control. This multi-functionality eliminates the need for separate detection and control circuits, reducing overall circuit complexity while maintaining effective threshold voltage control.
Solution Approach 2:
The patent merges the leakage current detection function and substrate bias control function into a unified circuit architecture. By combining these functions and using the source potential as the common signal for both detection and control, the patent reduces circuit design complexity and restrictions while maintaining reliable threshold voltage control.
Data Source
AI summary
A semiconductor integrated circuit apparatus includes an internal circuit having a MIS transistors on a semiconductor substrate and a substrate voltage control block that supplies a substrate voltage to the internal circuit and controls threshold voltages for the MIS transistors of the internal circuit. The apparatus also includes a leakage current detection MIS transistor and a leakage current detection circuit. The substrate voltage control block generates a substrate voltage based on comparison results of the comparator and applies the generated substrate voltage to the substrate of the leakage current detection MIS transistor and the substrate of the MIS transistors of the internal circuit. The substrate voltage control block includes a switch arranged between first and second input terminals of a comparator and a drain of the leakage current detection MIS transistor and a reference potential terminal, as well as an input data corrector that carries out substrate voltage adjustment.