Multi-Voltage I/O Device Bias Circuit for Transistor Protection
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Solution Overview
Problem
Semiconductor devices face reliability issues and potential damage when subjected to voltage levels exceeding their maximum operational voltage, as they are often required to comply with various signaling protocols that demand higher voltage transmission, exceeding the device's manufacturing process-defined voltage tolerances.
Innovation Solution
The implementation of a configurable transmission circuit with a bias voltage generation circuit that allows the semiconductor device to selectively operate at multiple voltage modes by generating a bias voltage, enabling transmission at voltages that exceed the maximum voltage tolerance without damaging the device's transistors, through the use of switch configurations and transistor networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the semiconductor device operates at voltage levels exceeding its maximum operational voltage to comply with signaling protocols, then the device can achieve compliance with various protocols and enhance operational flexibility, but the device faces reliability issues and potential transistor damage
Solution Approach 1:
A bias voltage generation circuit is introduced as an intermediary component between the power supply and the transmission circuit. This circuit generates a bias voltage that is lower than the transmit voltage, and this bias voltage is applied to transistor gates to ensure that voltage differences across any single transistor never exceed the maximum operational voltage, even when the transmission circuit operates at higher voltages for protocol compliance
Solution Approach 2:
The invention changes the voltage parameters dynamically by generating different bias voltages based on the selected transmission voltage mode. When operating at higher transmit voltages for protocol compliance, the bias voltage is adjusted to maintain safe voltage differences across transistors. The circuit can switch between different voltage modes (e.g., 1.8V, 2.5V, 3.3V) while always maintaining transistor safety through appropriate bias voltage selection
2Reliability
If the semiconductor device is designed to operate only at voltages within its maximum operational voltage, then the device maintains high reliability, but it cannot comply with signaling protocols that require higher voltage transmission
Solution Approach 1:
The transmission circuit is designed with multi-functionality to operate in multiple voltage modes (e.g., 1.8V, 2.5V, 3.3V) to comply with different signaling protocols. The bias voltage generation circuit automatically adapts to the selected mode, generating appropriate bias voltages to ensure transistor safety in each mode, thus making the single device universally compatible with multiple protocols while maintaining reliability
3Device complexity
If the device uses a fixed voltage operation mode, then the device structure remains simple, but it lacks the flexibility to operate at multiple voltage levels required by different protocols
Solution Approach 1:
The bias voltage generation circuit is designed to be dynamic rather than fixed. It can automatically adjust the bias voltage level based on the selected transmission voltage mode. The circuit includes switching mechanisms that enable it to transition between different bias voltage levels corresponding to different transmit voltage modes, providing adaptability without requiring complete redesign for each voltage mode
Data Source
AI summary
A device comprises, a first power source providing a first voltage, a second power source providing a second voltage less than the first voltage, a first bias voltage source providing a first bias voltage between the first voltage and the second voltage, a second bias voltage source providing a second bias voltage between the first voltage and the second voltage, the second bias voltage greater than or equal to the first bias voltage. The device also includes an output, a pull up network coupled in series between the first power source and the output pad including: a first gate coupled to the bias voltage source; and a second gate coupled to a signal that varies between first bias voltage and first power source. The device includes and a pull down network coupled between the output pad and second power source and including: a third gate coupled to the second bias voltage source; and a fourth gate coupled to a signal that varies between the second power source and the second bias voltage source.