Output Buffer Drive Calibration for Lower Noise and EMI
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Solution Overview
Problem
Conventional output buffers, designed for worst-case circuit environments, often exceed necessary driving ability in typical applications, leading to higher power noise, power consumption, and electromagnetic interference (EMI).
Innovation Solution
An adjusting method and circuit that dynamically adjusts the driving ability of an output buffer by sampling output voltage, comparing it to threshold values, and adjusting the driving ability class using a logic circuit to match the actual application environment, thereby optimizing power usage and reducing noise and EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output buffer is designed for worst-case circuit environment, then the output buffer can adjust the level of output signal in any circuit environment, but the output buffer has higher power noise, higher power consumption and higher electromagnetic interference
Solution Approach 1:
The patent implements dynamic adjustment of the output buffer's driving ability through a calibration process. The system initially sets the driving ability to a first level, measures the actual output signal level, compares it with a reference level, and then adjusts the driving ability to a second level based on the measurement results. This dynamic adjustment allows the output buffer to adapt to actual circuit conditions rather than being fixed for worst-case scenarios, thereby reducing power consumption, power noise, and electromagnetic interference while maintaining signal adjustment capability.
2Speed
If the output buffer uses higher driving ability, then the output signal level can be adjusted faster, but the power consumption and electromagnetic interference increase
Solution Approach 1:
The patent changes the driving ability parameter of the output buffer based on measured performance. By initially operating at a higher driving ability level and then adjusting it down to an optimal level based on actual signal measurement, the system achieves fast initial response while minimizing ongoing power consumption. The driving ability is adjusted according to the difference between actual and reference output levels, optimizing the balance between speed and energy efficiency.
Data Source
AI summary
A method adjusts driving ability of an output buffer. The output buffer has multiple driving ability classes. The method includes the following steps. First, the driving ability of the output buffer is initialized as an initial class among the driving ability classes. Next, a voltage at an output terminal of the output buffer is initialized to an initial voltage. Then, an input voltage is inputted via the input terminal at a first time instant. Next, an output voltage outputted from the output terminal is sampled to obtain a voltage value at a second time instant. Then, whether the voltage value satisfies a predetermined condition is judged. Next, if the voltage value satisfies the predetermined condition, the driving ability class of the output buffer is recorded and set.