By – Dr. Saswat Kumar Ram
Assistant Professor, Department of Electronics and Communication Engineering
SRM University – AP
Counterfeited and recycled integrated circuits (ICs) pose a serious and growing threat to the global electronics market, affecting quality, safety, reliability, and economic stability.
- What are Counterfeited and Recycled ICs?
- Counterfeited ICs: Fake components that are intentionally misrepresented as genuine (wrong manufacturer, altered markings, false specifications).
- Recycled ICs: Used ICs removed from discarded electronics, cleaned, re-marked, and sold as “new.”
- Major Threats to the Market
Reliability & Safety Risks
- Higher failure rates due to wear, electrostatic damage, or poor handling.
- Can cause system malfunctions, data loss, or safety-critical failures (aviation, medical devices, automotive).
- Latent defects may pass initial testing but fail in the field.
- Economic Impact
- Increased warranty claims and recalls.
- Higher testing and qualification costs for manufacturers.
- Damage to brand reputation and customer trust.
- Billions of dollars lost globally each year due to counterfeit components.
NBTI (Negative Bias Temperature Instability) Stress
NBTI stress is a reliability degradation mechanism that mainly affects PMOS transistors in CMOS technology and is a major concern in modern ICs. By Using this mechanism Aging Sensor can be designed.
An Aging Sensor based on a Ring Oscillator (RO) is used to detect whether an IC is fresh or recycled as shown in the diagram. The sensor consists of two identical ring oscillators:
- Reference RO (ROREF)
- Stressed RO (ROSTR)
A control module generates control signals to operate both ROs in either the stress phase or the authentication (measurement) phase.
- Fresh IC Behaviour
Both ROs are designed to oscillate at the same frequency initially.
The frequency difference is defined as:
FDIF=FREF−FSTR
For a new/fresh IC, ideally:
FDIF=0
However, due to process/manufacturing variations, FDIF can be slightly positive or negative. For a population of fresh ICs, the frequency difference distribution (Ffresh) is centered around zero.
- Stress Phase (Aging Acceleration)
ROSTR is subjected to accelerated NBTI stress (negative bias and elevated temperature).
ROREF is kept stress-free.
NBTI stress causes:
- Threshold voltage (Vₜ) increases in PMOS devices
- Reduction in drive current
- Decrease in oscillation frequency of ROSTR
Since ROREF degrades much less, the frequency difference FDIF increases with stress duration.
- Aged IC Behaviour
After stress:
The FDIF distribution for used/recycled ICs (Faged) shifts towards the right (positive direction).
Greater NBTI impact on ROSTR leads to:
Larger FDIF magnitude
Larger separation between Ffresh and Faged
- Misprediction Region (% m)
The overlap region between Ffresh and Faged represents misprediction percentage (% m):
In this region, it is difficult to classify an IC as fresh or recycled.
The % m is a key performance metric of the RO aging sensor.
- Performance Requirement
For efficient recycled IC detection:
The % m must be as low as possible
This requires:
-
- Narrow spreads of Ffresh and Faged
- Large separation between their mean values
A smaller overlap improves classification accuracy.
- Application in Energy Harvesting System (EHS) IC
The aging sensor is integrated into an Energy Harvesting System (EHS) IC to determine its operational age.Using VLSI simulation and reliability analysis tools, frequency degradation due to NBTI stress is measured and used for aging estimation and authentication.
- Importance in Counterfeit IC Detection
Counterfeited and recycled ICs pose serious risks to:
Product reliability
System safety
Economic viability
RO-based aging sensors provide an on-chip, low-cost, and effective solution for detecting recycled ICs, supporting secure supply chains and trustworthy electronics.
