Programmable Power Sense Circuit for Over-Voltage Trip-Point Control
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Solution Overview
Problem
Conventional power sense circuits face challenges in handling over-voltage stress, particularly in lower technology nodes like 5 nm, where input/output circuits operate at higher voltages exceeding the tolerance limit, leading to potential device failure and reliability issues, and lack scalability and flexibility in trip-point settings for varying input supply domains.
Innovation Solution
A programmable power sense circuit with over-voltage tolerance, utilizing stacked transistors, biasing with intermediate reference voltages, and level-shift logic to manage high and low voltage signals, along with programmable trip-point selection and extra bias voltage to support faster slew rates, ensuring reliable operation across a wide range of input voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power sense circuits are used, then the circuit can sense power supply voltage, but the circuit is prone to over-voltage stress and device breakdown when input voltage exceeds the maximum tolerance of devices in the destination domain
Solution Approach 1:
The patent introduces an intermediary voltage domain (VDD_INT) between the source domain (VDD_SRC) and destination domain (VDD_DST). This intermediate domain acts as a buffer that prevents direct over-voltage stress from propagating to devices in the destination domain. The level shifter circuit converts voltages from the source domain to the intermediate domain, and subsequent circuits convert from intermediate to destination domain, ensuring that no single stage experiences voltage differences exceeding device tolerance limits.
Solution Approach 2:
The patent segments the voltage conversion process into multiple stages: first from VDD_SRC to VDD_INT, then from VDD_INT to VDD_DST. Each stage uses dedicated level shifter circuits that are designed to handle specific voltage ranges. This segmentation ensures that the voltage difference across any single stage does not exceed the maximum tolerance of devices in either domain, preventing over-voltage stress and device breakdown.
2Reliability
If multiple dedicated power sniffer cells are used for different voltage domains, then each domain can be sensed reliably, but the device complexity and area increase
Solution Approach 1:
The patent creates a universal power sense circuit that can operate across multiple voltage domains through the use of an intermediate voltage domain. The same sensing circuitry can sense power levels in both the source domain and destination domain by referencing the intermediate domain, eliminating the need for separate dedicated power sniffer cells for each voltage domain. This multi-functional approach reduces device complexity and area while maintaining sensing reliability across different voltage domains.
3Productivity
If conventional power sense circuits are used, then the circuit can generate PWROK signal, but the circuit malfunctions at faster slew rates
Solution Approach 1:
The patent changes the operating parameters of the power sense circuit by introducing an intermediate voltage domain with optimized characteristics. The level shifter circuits are designed with specific transistor sizing and biasing that optimize the response time for detecting voltage transitions. This parameter optimization allows the circuit to accurately detect fast slew rates without malfunctioning, improving both the speed and reliability of power sensing compared to conventional circuits operating directly between voltage domains.
Data Source
AI summary
A power sensing circuit in a first voltage domain senses an input voltage from a second voltage domain and provides a power OK signal. The maximum supply voltage of the first voltage domain is above a maximum tolerance for devices in the first voltage domain. Accordingly, protection techniques are employed to ensure that the potential difference between any two terminals of devices in the power sensing circuit does not exceed the maximum tolerance limit. The protection techniques utilize reference voltage-based techniques including level shifting and use of protection devices in transistor stacks. An over-voltage tolerant Schmitt trigger circuit is also employed in the power sensing circuit. A trip point device on the input of the power sensing circuit utilizes a programmable bias voltage to adjust the trip point of the power sensing circuit to accommodate different maximum input voltages from the second voltage domain.