Voltage Conversion Circuit With Boosted Gate Drive for Faster ADC Switching
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Solution Overview
Problem
Conventional successive approximation type ADCs face a trade-off between operation speed and resolution, where improving operation speed decreases resolution and vice versa, due to the relationship between source potential and switching speed of transistors in the CMOS inverter.
Innovation Solution
A voltage conversion circuit with a high-voltage side transistor and a gate control unit that generates a control voltage higher than the high voltage, applied between the gate and source of the transistor, to enhance operation speed without increasing the output level, allowing the transistor to output a predetermined high voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the source potential of the P-type transistor is lowered to improve resolution, then the resolution of the ADC is improved, but the operation speed of the CMOS inverter decreases
Solution Approach 1:
The gate control unit is divided into multiple transistors (first P-type transistor, second P-type transistor, N-type transistor) that work together to generate the control voltage. This segmentation allows the control voltage to be generated through a multi-stage process, enabling the output transistor to achieve high voltage output while maintaining high operation speed through optimized switching control of individual transistor stages.
Solution Approach 2:
The gate control unit dynamically adjusts the control voltage based on the input signal state. When the input signal is at a low level, the control voltage is set to a high level to enable the output transistor to output the high voltage, thereby improving operation speed without increasing the output level and maintaining resolution.
2Speed
If the source potential of the P-type transistor is increased to improve operation speed, then the operation speed of the CMOS inverter is improved, but the input range is widened and the resolution of the ADC is reduced
Solution Approach 1:
The invention changes the parameter of control voltage (making it higher than the high voltage) rather than changing the output voltage level. This parameter change allows the transistor to switch faster (improving operation speed) while the output level remains constrained, thereby maintaining the ADC resolution without sacrificing speed.
3Speed
If the output level of the CMOS inverter is increased to improve operation speed, then the operation speed is improved, but the input range is widened and the resolution is reduced
Solution Approach 1:
The gate control unit acts as an intermediary between the input signal and the output transistor. It generates a control voltage that is higher than the high voltage, which enables the output transistor to switch faster, while the output level itself is not increased. This intermediary control mechanism resolves the contradiction by decoupling the control voltage level from the output voltage level.
Data Source
AI summary
An operation speed of a voltage conversion circuit is improved without increasing an output level of the voltage conversion circuit. The voltage conversion circuit is provided with a high-voltage side transistor and a gate control unit. In this voltage conversion circuit, the high-voltage side transistor outputs a predetermined high voltage higher than a predetermined reference voltage. Also, in the voltage conversion circuit, the gate control unit generates a predetermined control voltage higher than a predetermined high voltage from an input signal and applies the same between a gate and a source of the high-voltage side transistor, thereby allowing the high-voltage side transistor to output a predetermined high voltage.