Secure Voltage Regulator with Isolation and ADC Monitoring
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Solution Overview
Problem
Integrated voltage regulator circuits in ICs face challenges in securing internal supply voltage from external tampering, particularly in systems like FPGAs and SoCs, where side-channel attacks can compromise security and power management is complex due to multiple supply voltages and current requirements.
Innovation Solution
An integrated circuit (IC) system with an integrated voltage regulator circuit, isolation circuitry, and security circuitry that monitors internal supply voltage parameters using an ADC to detect tampering and generate error signals, preventing unauthorized modifications and protecting against differential power analysis attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an integrated voltage regulator circuit is used to provide internal supply voltage, then power management capability is improved, but security vulnerability to side-channel attacks increases
Solution Approach 1:
The voltage regulator circuit is segmented into multiple isolated domains: a first domain for the regulated output voltage and a second domain for the reference voltage. This segmentation prevents attackers from accessing both domains simultaneously through external pins, thereby reducing side-channel attack vectors while maintaining full power management functionality.
Solution Approach 2:
An internal reference voltage generated within the IC chip serves as an intermediary between the external supply voltage and the regulated output voltage. This intermediary reference voltage is used for both regulation and ADC conversion, eliminating the need to expose reference voltage pins externally and reducing security vulnerabilities.
2Adaptability or versatility
If multiple external pins are used for voltage regulation, then flexibility in power management is improved, but ease of operation decreases due to tampering risks
Solution Approach 1:
The reference voltage functionality is extracted from external pins and implemented as an internal circuit that generates the reference voltage using the regulated output voltage. This eliminates the need for external reference voltage pins, reducing tampering risks while maintaining power management flexibility through programmable control.
Solution Approach 2:
The voltage regulator circuit uses its own regulated output voltage to generate the reference voltage internally, making the system self-sufficient. This self-service approach eliminates dependencies on external reference voltage sources and reduces the number of pins requiring external connection, thereby improving ease of operation.
3Reliability
If ADC circuit is added to monitor voltage parameters, then security detection capability is improved, but device complexity increases
Solution Approach 1:
The ADC circuit is designed to serve multiple functions: monitoring the regulated output voltage for tamper detection, measuring voltage levels for power management control, and providing diagnostic information. This multi-functionality reduces the need for separate monitoring circuits, thereby limiting the increase in device complexity.
Solution Approach 2:
The ADC circuit is merged with the existing voltage regulator control logic, allowing the same hardware resource to be used for both regulation control and security monitoring. This integration approach minimizes additional complexity by sharing common infrastructure such as comparators, reference circuits, and control registers.
Data Source
AI summary
A system includes an integrated circuit (IC) chip with connections to plurality of external pins. An integrated voltage regulator circuit is configured to provide an internal supply voltage to the IC chip. Isolation circuitry is configured to inhibit tampering of the internal supply voltage through the external pins. An analog to digital converter (ADC) circuit is configured to monitor parameters of the internal supply voltage. Security circuitry is configured to detect, using the monitored parameters, indications of tampering and to generate an error signal in response to detecting an indication of tampering.