Bootstrap Sampling Switch Control for Low On-Resistance ADCs
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Solution Overview
Problem
The challenge is to reduce the on-resistance of sampling switches in analog-to-digital converters while minimizing their size and increasing integration, as larger switches lead to increased parasitic capacitance and decreased signal-to-noise and distortion ratio (SNDR).
Innovation Solution
A switch device comprising a non-overlap circuit, bootstrap circuits, and power transfer circuits that control voltage levels and signal transitions to minimize on-resistance, using a non-overlap circuit to ensure different transition times for control signals and bootstrap circuits to increase node voltages, thereby reducing resistance in switch circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the size of the sampling switch is increased, then the on-resistance value becomes smaller, but the SNDR decreases due to the increase in parasitic capacitance
Solution Approach 1:
The patent changes the voltage parameter by applying a boosted voltage (higher than the signal voltage) to the switch control terminal. This voltage boosting allows the switch to achieve low on-resistance without increasing physical size, thereby maintaining small parasitic capacitance and preserving SNDR performance.
2Productivity
If the size of the sampling switch is reduced to increase integration, then the degree of integration increases, but the on-resistance increases
Solution Approach 1:
The patent compensates for the increased on-resistance of smaller switches by applying a boosted control voltage. This parameter change in voltage allows miniaturized switches to maintain low effective resistance, enabling high integration while preserving signal quality.
3Manufacturing precision
If a bootstrap circuit is used to increase node voltage, then the on-resistance decreases, but the device complexity increases
Solution Approach 1:
The bootstrap circuit performs preliminary voltage boosting of the control signal before it reaches the switch. This advance preparation of the control voltage ensures the switch operates with optimally low resistance during the sampling phase, without requiring complex real-time control mechanisms.
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
The solution effectively decreases on-resistance in switch circuits, improving SNDR and reducing power loss, electrical stress, and signal distortion, while allowing for smaller switch sizes and higher integration.
Implementation Method 1
a first bootstrap circuit that increases a voltage of a first node, based on the first control signal
Implementation Method 2
a first power transfer circuit that receives the voltage of the first node and outputs a first voltage, based on the second control signal
Data Source
AI summary
A switch device includes a non-overlap circuit outputting first to fourth control signals, voltage levels of which transition at different time points, based on an enable signal, a first bootstrap circuit increasing a voltage of a first node, based on the first control signal, a first power transfer circuit receiving the voltage of the first node and outputs a first voltage, based on the second control signal, a first switch circuit, in response to the first voltage, outputting a first signal received at an input of the first switch circuit to a third node, a second bootstrap circuit, a second power transfer circuit, and a second switch circuit performing the same functions as the first bootstrap circuit, the first power transfer circuit, and the first switch circuit to output a second signal to the third node based on the third control signal and the fourth control signal.