Output Buffer Self-Calibration for Stable Data Valid Windows
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Solution Overview
Problem
Output buffers in integrated circuits are sensitive to process, voltage, and temperature (PVT) conditions, leading to variations in data valid windows, which affect performance and reliability, especially at high operating speeds.
Innovation Solution
An integrated circuit with an output buffer and control circuit that adjusts driving strength using control signals generated by a reference delay circuit and a delay emulation circuit, which are designed to be insensitive to PVT conditions, ensuring consistent output timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the operating speed of the integrated circuit is increased, then the productivity is improved, but the reliability deteriorates due to reduced data valid window
Solution Approach 1:
The output buffer's driving strength is made dynamically adjustable through multiple control inputs that select different driving strength levels. This dynamic adaptation allows the buffer to optimize its performance characteristics for different operating conditions, maintaining reliable operation at high speeds by adjusting the data valid window according to the actual operating speed and PVT conditions.
Solution Approach 2:
The invention changes the electrical parameters of the output buffer by providing multiple control inputs that adjust the driving strength. By varying the control signals applied to these inputs, the buffer can modify its output characteristics, including rise/fall times and current drive capability, to compensate for PVT variations and maintain data validity at high operating speeds.
2Reliability
If the driving strength of the output buffer is increased to maintain data valid window, then the reliability is improved, but the power consumption increases
Solution Approach 1:
The control circuit dynamically adjusts the driving strength based on actual operating conditions rather than using a fixed high-drive configuration. By monitoring PVT conditions and operating speed, the system selects the appropriate driving strength level, consuming more power only when necessary to maintain data validity, and reducing power consumption when lower drive strength suffices.
Solution Approach 2:
The invention provides multiple controllable parameters for the output buffer, allowing the system to optimize the trade-off between driving strength and power consumption. By adjusting the control inputs, the system can select from different power consumption levels while maintaining adequate data valid window, thus reducing unnecessary power dissipation.
3Reliability
If the output buffer is made insensitive to PVT conditions, then the reliability is improved, but the device complexity increases due to additional control circuits
Solution Approach 1:
The control circuit is designed to automatically sense and respond to PVT conditions without requiring external intervention or complex calibration systems. The circuit self-adjusts the output buffer's driving strength based on internal monitoring of operating conditions, providing PVT compensation through a relatively simple autonomous control mechanism that minimizes additional complexity.
Solution Approach 2:
The control circuit performs multiple functions: it monitors PVT conditions, determines appropriate driving strength levels, generates control signals, and adjusts the output buffer characteristics. By consolidating these functions into a single integrated control block, the invention achieves PVT insensitivity without proportionally increasing overall device complexity.
Data Source
AI summary
An integrated circuit includes an output buffer and a control circuit. The output buffer has a signal input, a signal output, and a set of control inputs. The output buffer has an output buffer delay, and a driving strength adjustable in response to control signals applied to the set of control inputs. The control circuit is connected to the set of control inputs of the output buffer. The control circuit uses first and second timing signals to generate the control signals, and includes a reference delay circuit that generates the first timing signal with a reference delay, and a delay emulation circuit that generates the second timing signal with an emulation delay that correlates with the output buffer delay.