Shared-Impedance High-Speed IO Buffer for Bidirectional Modes
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Solution Overview
Problem
Conventional IO buffers require separate design for driving and receiving modes, resulting in larger area and reduced flexibility to meet different impedance and linearity requirements across applications.
Innovation Solution
A bi-directional IO buffer design where the driver and receiver share impedance in both modes, utilizing switch elements and resistive elements to select between driving and receiving modes efficiently, reducing the overall area and enabling flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate design for driving and receiving modes is used, then impedance and linearity requirements are met, but area increases
Solution Approach 1:
The patent merges the driving and receiving mode circuitries by having transistors Q1 and Q2 serve dual functions. In driving mode, Q1 and Q2 act as output drivers, while in receiving mode, they contribute to the input impedance along with Q3 and Q4. This consolidation allows a single IO buffer circuit to meet both driving and receiving impedance requirements without requiring separate dedicated circuit blocks for each mode, thereby reducing the overall area.
Solution Approach 2:
The patent implements multi-functionality where the same transistors (Q1, Q2, Q3, Q4) perform different functions depending on the operational mode. The control unit configures these transistors to operate in driving mode or receiving mode based on the OE signal state. This universal design allows the IO buffer to adapt to different applications requiring either driving or receiving functionality, eliminating the need for separate dedicated circuits and reducing area consumption.
2Reliability
If separate design for driving and receiving modes is used, then mode-specific performance is optimized, but flexibility decreases
Solution Approach 1:
The patent employs dynamic reconfiguration of the circuit topology through the control unit that responds to the OE signal. When OE is asserted (driving mode), Q3 and Q4 are turned off while Q1 and Q2 are configured for output driving. When OE is negated (receiving mode), Q1 and Q2 are turned off and Q3 and Q4 are configured for receiving with proper impedance matching. This dynamic switching capability allows the same hardware to adapt to different operational requirements, providing both optimized mode-specific performance and flexibility for different applications.
3Area of stationary object
If shared impedance circuitry is used, then area is reduced, but design complexity increases
Solution Approach 1:
The patent segments the control logic into distinct functional blocks: the control unit that monitors the OE signal, and the transistor configuration logic that responds to OE assertions or negations. This segmentation of control functions makes the complex shared impedance design more manageable by breaking down the control mechanism into discrete, well-defined stages: detection of OE state, determination of operational mode, and configuration of appropriate transistor states. This structured approach to controlling the shared circuitry reduces the perceived design complexity while maintaining area efficiency.
Data Source
AI summary
A bi-directional buffer is provided. The buffer includes a driver, a receiver, and a circuitry configured to select a driving mode in response to detecting a first condition and to select a receiving mode in response to detecting a second condition. The driving mode has a first impedance and the receiving mode has a second impedance. The second impedance is partially contributed from the driver.