Bootstrapped Switch Circuit for Wide-Range Linearity and Bandwidth
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Solution Overview
Problem
Integrated circuits face challenges in achieving high bandwidth and linearity over a wide signal amplitude range in switches used for signal acquisition and transmission, particularly in sample and hold circuits and multiplexers.
Innovation Solution
The implementation of bootstrapped switches, which utilize level shifter circuitry to generate control signals based on input voltage, improving the linearity and bandwidth by reducing gate-source voltage variation during switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional switches are used for signal acquisition and transmission, then the circuit structure remains simple, but the bandwidth and linearity over wide signal amplitude range are limited
Solution Approach 1:
The patent implements dynamic control of the switch by using a level shifter circuit that generates a time-varying control signal. This control signal dynamically adjusts the gate-source voltage of the transistor during switching operations, enabling the switch to maintain optimal performance characteristics across different signal amplitudes and frequencies, thereby achieving high bandwidth without excessive complexity
Solution Approach 2:
The level shifter circuit changes the control parameter (gate voltage) dynamically during switching operations. By adjusting the control signal voltage level based on the input signal characteristics, the switch maintains consistent linearity and bandwidth performance across wide signal amplitude ranges, resolving the contradiction between performance and simplicity
2Manufacturing precision
If conventional switches are used without level shifting, then the circuit complexity remains low, but gate-source voltage variation degrades linearity over wide signal amplitude range
Solution Approach 1:
The level shifter circuit acts as an intermediary between the control signal source and the transistor gate. It processes the control signal to provide the precise gate-source voltage needed for linear switching operation, eliminating direct coupling between the control logic and the switch, thereby improving linearity while maintaining manageable circuit complexity
Solution Approach 2:
The level shifter circuit implements a feedback mechanism where the control signal is adjusted based on the desired gate-source voltage requirements. This feedback control ensures that the switch operates in its linear region across wide signal amplitude ranges, achieving high manufacturing precision in terms of signal fidelity
3Speed
If gate-source voltage is allowed to vary during switching, then the circuit operation is simple, but bandwidth is limited due to voltage variation effects
Solution Approach 1:
The patent embraces dynamic control by implementing a level shifter that actively adjusts the gate-source voltage during switching operations. This dynamic adjustment allows the switch to maintain high bandwidth performance by optimizing the control voltage in real-time, accepting increased operational complexity as the price for achieving superior speed performance
Data Source
AI summary
An apparatus includes: buffer circuitry having a buffer input and a buffer output; a transistor coupled between the buffer output and a current terminal, the transistor having a control terminal; and level shifter circuitry having a level shifter input and a level shifter output, the level shifter input coupled to the buffer input, and the level shifter output coupled to the control terminal.