Analog IC Protection via Tuning Range Obfuscation
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Solution Overview
Problem
Existing methods for protecting analog and mixed signal integrated circuit intellectual property (ICIP) are inadequate, as they require significant additional transistors and gates to create a finite state engine, which increases complexity and cost, and are difficult to adapt due to the fewer transistors and logic gates in these circuits, making them vulnerable to unauthorized use.
Innovation Solution
The method employs the requirements for correct tuning of analog circuits in analog and mixed-signal ICs to create a large number of finite state engine states, providing an obfuscated mechanism to disable the IC until a proper enabling input or 'key' is provided, using techniques such as increased adjustment ranges, clipping circuits, and physically unclonable functions to protect the ICIP with minimal added circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional digital transistors and gates are added to create a finite state engine for ICIP protection, then protection capability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the protection mechanism with the existing analog tuning circuits by using the same circuit elements (varactors, resonators, amplifiers) to serve dual purposes: both analog signal processing and digital protection state machine operations, thereby avoiding additional transistors and gates
Solution Approach 2:
The patent makes the analog circuits universal by enabling them to perform multiple functions - traditional analog signal processing and finite state engine operations for ICIP protection - through the use of tunable parameters and enabling/disabling mechanisms that allow the same hardware to serve different functional roles
2Reliability
If additional digital transistors and gates are added to create a finite state engine for ICIP protection, then protection capability is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines protection functionality with existing analog circuits, eliminating the need for separate protection circuitry and reducing overall manufacturing cost while maintaining protection capability
Solution Approach 2:
By making circuits multi-functional, the patent reduces the total component count required, directly lowering manufacturing costs while providing robust ICIP protection through the same hardware infrastructure
3Reliability
If the adjustment range of analog circuits is increased to create more finite state engine states, then protection capability is improved, but circuit bandwidth requirements increase
Solution Approach 1:
The patent transitions from temporal dimension (bandwidth) to parametric dimension (tuning range) by using variable capacitance values through varactor control, allowing multiple states to be achieved through parameter variation rather than time-based transitions, thereby maintaining protection capability without increasing bandwidth requirements
Data Source
AI summary
A method for protecting analog or mixed signal ICIP uses adjustment requirements of analog circuits to provide an obfuscated mechanism for preventing unauthorized use of an analog or mixed-signal IC (“AIC”) by disabling the AIC until application of an adjustment signal that is within a narrow enabling subrange. Embodiments significantly increase the adjustment range beyond the enabling subrange, and/or omit AIC tuning outputs that are not required for operation of the IC. Embodiments include “clipping” circuits that render the AIC outputs unresponsive to tuning signals outside of the enabling subrange. Information regarding the enabling subrange and/or a separate enabling IC can be provided to authorized users, and/or enabling bits of a digital adjustment input can be permanently set by the ICIP owner after AIC manufacture. The ICIP can be further protected by a security feature that can be unique to each AIC, and/or by using a two-foundry production method.