Track-and-Hold Gate Buffer Without Bootstrap Circuitry
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Track and hold circuits face challenges in achieving high speed, large bandwidth, and linearity, particularly when the supply voltage is low compared to the input signal, requiring complex bootstrap circuitry to maintain a constant gate-source voltage for the pass gate transistor.
Innovation Solution
A track and hold circuit utilizing a buffer circuit supplied by a higher voltage rail to generate the gate voltage for the main transistor, eliminating the need for bootstrap techniques and allowing the gate voltage to exceed the supply voltage, thereby improving linearity and reducing charge injection and current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If bootstrap circuitry is used to maintain constant gate-source voltage, then linearity is improved, but device complexity increases
Solution Approach 1:
The patent extracts the voltage step generation function from the main circuit by using a separate buffer circuit supplied by a higher voltage rail. This eliminates the need for complex bootstrap circuitry while maintaining the required gate-source voltage for linear operation.
Solution Approach 2:
The patent introduces a buffer circuit as an intermediary component that generates the voltage step from a higher voltage rail. This mediator provides the necessary gate voltage control without requiring direct bootstrap connections, simplifying the overall circuit architecture.
2Productivity
If higher gate voltage is applied to switch transistor hard on, then efficiency is improved, but device breakdown risk increases
Solution Approach 1:
The patent changes the voltage parameter by introducing a higher voltage rail (e.g., 3.3V or 5V) compared to the core supply voltage (e.g., 1.8V). This allows the buffer circuit to generate sufficient gate-source voltage for hard switching while the main transistor operates within its safe voltage limits.
3Use of energy by moving object
If supply voltage is kept low for power saving, then energy consumption is reduced, but gate voltage capability is limited
Solution Approach 1:
The patent adds another voltage dimension by introducing a higher voltage rail that is independent of the core supply voltage. This allows the core circuit to operate at low voltage for power saving while the buffer circuit uses the higher voltage dimension to provide adequate gate drive capability.
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 solution enables efficient operation with low charge injection and high bandwidth, allowing for faster transitions between track and hold phases without the need for complex bootstrap circuitry, while maintaining good linearity and enabling the use of smaller transistors.
Implementation Method 1
a buffer circuit for generating a gate voltage for turning on the main transistor during a track phase, wherein the buffer circuit is adapted to derive a gate voltage based on the input or output voltage of the circuit and a voltage step
Implementation Method 2
a storage capacitor for storing the output voltage during a hold phase during which the main transistor is turned off
Data Source
AI summary
A track and hold circuit has a main transistor for which the gate voltage is provided by a buffer circuit which is supplied with a different voltage supply than the circuit of the main transistor. This avoids the need for a bootstrap circuit.