Single-Ended Output Driver Buffer With Precharged Capacitive Noise Shielding
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Solution Overview
Problem
Existing output driver circuits face challenges in buffering reference voltages effectively due to noise coupling, leading to increased current consumption and chip area requirements, especially when implementing noise reduction methods like buffers and delay elements.
Innovation Solution
The proposed solution involves using capacitors precharged to specific voltages and switches to connect these capacitors to the gates of output driver transistors, followed by connecting the reference voltages after a brief time period, thereby buffering noise without excessive current consumption or large chip area requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If buffers are used to reduce noise coupling to driver transistors, then noise reduction is improved, but DC current consumption increases significantly
Solution Approach 1:
The patent implements periodic buffering action by using switches controlled by timing signals to connect buffers to driver transistors only during specific time windows after switching events. This allows noise reduction to be applied periodically rather than continuously, significantly reducing DC current consumption while maintaining noise protection benefits during critical periods
Solution Approach 2:
The patent uses delay elements to generate timing signals that activate buffers in advance of or during the period when noise coupling is most problematic. This preliminary action ensures noise protection is in place before noise coupling occurs, while allowing buffers to be deactivated during periods when noise is not an issue, reducing overall power consumption
2Use of energy by moving object
If switches and delay elements are added to reduce buffer power consumption, then DC current consumption decreases, but chip area increases significantly
Solution Approach 1:
The patent designs switches and delay elements to serve multiple functions: switches not only control buffer activation but also provide signal routing and timing control; delay elements not only reduce power consumption by timing buffer activation but also provide signal synchronization. This multi-functionality reduces the need for separate dedicated components, minimizing overall chip area increase
3Object-affected harmful factors
If constant DC current is used to power buffers, then noise buffering is maintained continuously, but power consumption increases for large numbers of output drivers
Solution Approach 1:
The patent replaces constant DC current powering with periodic pulsing of buffer power supply, synchronized with driver transistor switching events. Buffers receive power only during time windows when noise coupling is expected, allowing continuous noise buffering protection while dramatically reducing average power consumption across large numbers of output drivers
Solution Approach 2:
The patent uses feedback from driver transistor switching signals to control buffer power supply timing. The switching events of driver transistors provide feedback that triggers buffer activation and power supply, ensuring noise buffering is applied exactly when needed without requiring constant power, thus reducing overall power consumption while maintaining effective noise protection
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively buffers noise with minimal current consumption (approximately 200-300 μA for 500-600 ps per toggle) and reduced chip area, maintaining control benefits for output driver transistors while reducing power and area impact.
Implementation Method 1
a first capacitor adapted to be precharged to a first voltage, a first switch adapted to connect the first capacitor to the gate of the first output driver transistor
Data Source
AI summary
Circuits and related methods are provided for buffering reference voltages from noise associated with output driver transistors. In one example, an output driver buffer circuit includes an output driver transistor adapted to adjust an output voltage of an output pad. The circuit also includes a pre-driver circuit connected to a gate of the output driver transistor. The pre-driver circuit is adapted to receive a reference voltage to control the output driver transistor. The pre-driver circuit includes a precharged capacitor, a first switch adapted to connect the capacitor to the gate, and a second switch adapted to connect the reference voltage to the gate. The second switch is adapted to operate following a time period after the capacitor is connected to the gate. The capacitor is adapted to buffer noise associated with the output driver transistor during the time period.