CMOS IDDQ Measurement Apparatus With Substrate Voltage Control
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Solution Overview
Problem
The miniaturization of CMOS LSIs has led to increased leak currents, making it difficult to distinguish between normal and defective power supply currents, and noise currents obscure the measurement of defective currents in conventional measurement apparatuses.
Innovation Solution
A measurement apparatus that includes a voltage detecting section, a voltage control section to suppress leak current fluctuations, and an IDDQ acquiring section, which controls substrate voltages to isolate and measure IDDQ current accurately, and an optional system that applies varying power supply voltages and temperatures to calculate internal resistance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the miniaturization of CMOS LSIs is pursued to improve integration density, then the leak current increases, but the ability to distinguish defective current from normal leak current deteriorates
Solution Approach 1:
A bypass capacitor is introduced as an intermediary component connected in parallel with the device under measurement. This capacitor filters out noise currents from the power supply, allowing the defective current to be measured accurately even in miniaturized CMOS LSIs where leak current is high. The capacitor acts as a mediator that separates the harmful noise from the measurement signal.
Solution Approach 2:
The measurement method changes the measurement parameters by measuring the power supply current at multiple different power supply voltages and calculating the differential value between measurements. This parameter change approach allows differentiation between normal leak current (which changes predictably with voltage) and defective current (which shows abnormal differential changes), thereby improving defect detection accuracy in miniaturized devices.
2Ease of operation
If conventional measurement methods are used to measure power supply current, then the measurement process is simple, but the defective current is buried in noise current and cannot be accurately measured
Solution Approach 1:
A bypass capacitor is introduced as an intermediary component connected in parallel with the device under measurement. This capacitor filters out noise currents from the power supply, allowing the defective current to be measured accurately even in miniaturized CMOS LSIs where leak current is high. The capacitor acts as a mediator that separates the harmful noise from the measurement signal.
Solution Approach 2:
The measurement method uses feedback by measuring power supply current at multiple different power supply voltages and using the differential value between measurements to identify defective current. This feedback mechanism allows the system to distinguish defective current from normal leak current by comparing measurements taken under different conditions, thereby improving measurement accuracy while maintaining operational feasibility.
3Adaptability or versatility
If power supply voltage fluctuates, then the measurement process is flexible, but the leak current fluctuates making accurate IDDQ measurement difficult
Solution Approach 1:
The voltage control section uses feedback from the voltage detecting section to dynamically adjust the substrate voltage and compensate for power supply voltage fluctuations. By continuously monitoring the actual power supply voltage and adjusting the substrate voltage accordingly, the system maintains constant leak current despite power supply variations, enabling accurate IDDQ measurement while preserving power supply flexibility.
Solution Approach 2:
The voltage control section applies a counteracting voltage adjustment to the substrate voltage that opposes the effect of power supply voltage fluctuations on leak current. By controlling the substrate voltage in the opposite direction to the power supply voltage changes, the system counterweights the harmful effect of voltage fluctuations and maintains stable leak current for accurate measurement.
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
Enables accurate detection of defects in CMOS circuits by isolating and measuring IDDQ current, effectively distinguishing between normal and defective currents, and calculating internal resistance values to identify defects.
Implementation Method 1
a voltage control section that suppresses a fluctuation of a leak current of the device under measurement caused by a fluctuation of the power supply voltage by controlling a substrate voltage of the device under measurement based on the power supply voltage detected by the voltage detecting section
Implementation Method 2
an IDDQ acquiring section that acquires a value of an IDDQ current of the device under measurement by measuring a prescribed characteristic of the device under measurement while the voltage control section suppresses the fluctuation of the leak current
Data Source
AI summary
A measurement apparatus that detects a defect in a device based on the quiescent current (IDDQ) of a CMOS LSI or the like detects the defect by measuring the value of IDDQ that flows when a logic vector is applied. However, the miniaturization of CMOS LSIs has caused an increase in the leak current flowing through a normal CMOS circuit. This makes it difficult to distinguish between the power supply current flowing in a defective CMOS circuit and the leak current flowing through a normal CMOS circuit. By applying the logic vector after suppressing the fluctuation of the leak current by controlling the power supply voltage applied to the device under measurement and the voltage applied to the substrate of the device under measurement, the measurement apparatus of the present invention can measure the power supply current flowing through a defective CMOS circuit to detect the defect in the CMOS circuit.