Output Buffer Edge-Rate Control for Matched Signal Timing

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Solution Overview

Problem

Modern IC designs require precise signal accuracy, particularly in output buffer circuits, where matching rising and falling times is crucial for driving larger loads, but existing technologies struggle to effectively control these times to meet the demands of varying load sizes.

Innovation Solution

An output buffer apparatus comprising a clamp circuit, a bias circuit, and a rate control circuit for rising/falling edges, utilizing transistor pairs to generate clamp and bias voltages that control the rate of the buffered signal, ensuring matched rising and falling times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If driving capabilities are increased to meet larger load demands, then the rising time and falling time of the driving signal are reduced, but the buffer circuit cannot provide correct signals for different load sizes

Engineering Contradiction:

Improverising time and falling timeVSAvoidsignal correctness for different load sizes

Core Design Contradiction:

SpeedVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic control of the buffer circuit by introducing a rate control circuit that adjusts the rising/falling edge rates based on load conditions. The clamp circuit and bias circuit dynamically modify the operating point of the buffer transistor, enabling the circuit to adapt its signal characteristics to different load sizes while maintaining correct signal levels.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes key electrical parameters (clamp voltage and bias voltage) to control the buffer circuit's behavior. By varying these parameters through the clamp and bias circuits, the system can adjust the rising/falling edge rates and signal levels to match different load requirements, resolving the contradiction between speed and adaptability.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the buffer circuit is designed for precise signal accuracy, then signal correctness is improved, but the ability to drive larger loads with appropriate rising/falling times is compromised

Engineering Contradiction:

Improvesignal accuracyVSAvoiddriving capability for larger loads

Core Design Contradiction:

Measurement precisionVSPower

Solution Approach 1:

The patent segments the buffer circuit into distinct functional blocks: a clamp circuit for voltage clamping, a bias circuit for current biasing, and a rate control circuit for edge rate control. This segmentation allows each block to independently optimize its function - the clamp and bias circuits ensure signal accuracy while the rate control circuit manages the driving capability for different load sizes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The rate control circuit acts as an intermediary between the buffer circuit and the load. It receives the buffered signal and controls the rising/falling edge rates before delivering the signal to the load, thereby decoupling the signal accuracy requirements from the power/driving capability requirements and allowing both to be optimized independently.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9559676B1Output buffer apparatus for controlling rate of rising/falling edge of buffered signal

Publication Date: 2017.01.31 VIA LABS INC

AI summary

An output buffer apparatus is provided. A clamp circuit outputs a clamp voltage through a transistor pair having a first configuration. A bias circuit outputs a bias voltage through a transistor pair having a second configuration. A rate control circuit for rising/falling edge buffers an input signal according to the clamp voltage and the bias voltage to generate a buffered signal.