Bootstrap Switch Non-Overlap Timing With Reduced Jitter and Crosstalk

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Solution Overview

Problem

Existing bootstrap switches suffer from crosstalk due to delay circuits and clock drivers that introduce jitter/skew into non-overlapping clock signals, degrading performance.

Innovation Solution

A bootstrap circuit design using a boost capacitor and transistors to maintain a constant gate-to-source voltage for switch transistors, reducing on-resistance variation and incorporating a simplified timing circuit with fewer gates to minimize jitter/skew.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If timing circuits with delay circuits and clock drivers are used to generate non-overlapping clock signals, then crosstalk between channels is reduced, but jitter and skew are introduced into the clock signals

Engineering Contradiction:
ImprovecrosstalkVSAvoidjitter and skew
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent extracts and removes the problematic delay circuits and clock drivers from the timing circuit. By eliminating these components that introduce jitter and skew, the system achieves non-overlapping clock signals without the harmful timing variations, while still maintaining channel isolation through alternative means.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses a simplified timing circuit that generates clock signals without complex delay circuits. Instead of copying the traditional approach with multiple delay stages, it employs a streamlined design that achieves the same non-overlapping function with fewer components, thereby reducing jitter and skew.

Inventive Principle:
Principle #26Copying

2Reliability

If traditional timing circuits with multiple delay circuits are used, then non-overlapping clock signals are generated, but the circuit complexity increases

Engineering Contradiction:
Improvenon-overlapping clock signal generationVSAvoidtiming circuit complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes unnecessary delay circuits and clock drivers from the timing circuit, keeping only the essential components needed to generate non-overlapping clock signals. This extraction simplifies the overall circuit architecture while maintaining the core functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using multiple delay circuits to achieve non-overlapping signals, the patent inverts the approach by using a simplified circuit that generates the non-overlapping signals directly without relying on cascaded delay stages, thereby reducing complexity.

Inventive Principle:
Principle #13The other way round (Inversion)

3Object-affected harmful factors

If delay circuits are used to generate non-overlapping clock signals, then channel isolation is improved, but manufacturing precision requirements increase due to jitter and skew

Engineering Contradiction:
Improvecrosstalk reductionVSAvoidtiming precision
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent extracts and eliminates the delay circuits that cause timing variations. By removing these components, the system achieves channel isolation without introducing jitter and skew, thereby reducing manufacturing precision requirements for timing-critical components.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent implements a simplified timing circuit that copies the essential function of generating non-overlapping signals without replicating the complex delay circuitry. This approach maintains channel isolation while avoiding the timing precision issues associated with traditional delay-based designs.

Inventive Principle:
Principle #26Copying

Data Source

PatentUS20250266822A1Non-overlapping generation technique for bootstrap switches
Publication Date: 2025.08.21 QUALCOMM INC
  • US20250266822A1 patent drawing
  • US20250266822A1 patent drawing
  • US20250266822A1 patent drawing

AI summary

A system includes a bootstrap circuit having an input and an output. The bootstrap circuit includes a boost capacitor having a first terminal and a second terminal, a first transistor coupled between the first terminal of the boost capacitor and the output of the bootstrap circuit, a second transistor, and a third transistor, wherein the second transistor and the third transistor are coupled in series between a gate of the first transistor and the second terminal of the boost capacitor. The system also includes a switch transistor, wherein a gate of the switch transistor is coupled to the output of the bootstrap circuit, and a terminal of the switch transistor is coupled to the input of the bootstrap circuit.