Bootstrapped Switch Buffer Split for Kickback Reduction
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Solution Overview
Problem
The on-resistance of transistors used as switches varies with the gate-to-source voltage, causing signal distortion due to voltage-dependent resistance, and bootstrap circuits introduce kickback disturbances when used to stabilize this resistance.
Innovation Solution
A system with separate buffers for driving signal paths and bootstrap circuits, where one buffer is configured for low noise and the other for reduced kickback, decoupling noise performance from kickback mitigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a bootstrap circuit is used to stabilize the gate-to-source voltage of the transistor, then the on-resistance becomes approximately constant and linearity is improved, but kickback disturbances are introduced to the signal path
Solution Approach 1:
The patent divides the buffer circuit into two separate buffers: a first buffer for driving the signal path and a second buffer for driving the bootstrap circuit. This segmentation isolates the kickback disturbance generated by the bootstrap circuit from the signal path, while still maintaining the stability benefit of the bootstrap circuit for constant on-resistance.
Solution Approach 2:
The patent extracts the bootstrap circuit driving function from the signal path buffer and assigns it to a separate second buffer. This extraction removes the harmful kickback effect from the signal path while preserving the useful function of driving the bootstrap circuit to stabilize transistor on-resistance.
2Device complexity
If the gate-to-source voltage varies with signal voltage, then the transistor structure is simple, but the on-resistance varies causing signal distortion
Solution Approach 1:
The patent introduces a bootstrap circuit as an intermediary mechanism that generates a gate voltage tracking the signal voltage. This intermediary component compensates for the voltage-dependent on-resistance effect, improving signal linearity while maintaining a relatively simple transistor structure.
Solution Approach 2:
The patent dynamically changes the gate voltage parameter to track the signal voltage, thereby maintaining a constant gate-to-source voltage difference. This parameter adjustment compensates for the inherent voltage-dependent resistance characteristic of the transistor, improving linearity without fundamentally changing the transistor structure.
3Device complexity
If a single buffer drives both the signal path and bootstrap circuit, then the device complexity is reduced, but noise performance is degraded due to kickback coupling
Solution Approach 1:
The patent segments the buffer function into two independent buffers: one dedicated to signal path driving and another dedicated to bootstrap circuit driving. This segmentation prevents kickback noise from coupling into the signal path, thereby improving noise performance while accepting increased device complexity.
Solution Approach 2:
The patent introduces a dedicated second buffer as an intermediary between the signal source and the bootstrap circuit. This intermediary buffer isolates the signal path from the kickback disturbances generated by the bootstrap circuit, improving noise performance at the cost of additional circuit complexity.
Data Source
AI summary
A system includes a switch transistor, and a bootstrap circuit having an input and an output, wherein the output of the bootstrap circuit is coupled to a gate of the switch transistor. The system also includes a first buffer having an input and an output, wherein the output of the first buffer is coupled to a terminal of the switch transistor. The system further includes a second buffer having an input and an output, wherein the input of the second buffer is coupled to the input of the first buffer, and the output of the second buffer is coupled to the input of the bootstrap circuit.