Sampling Circuit Duty Ratio Control for Stable Gate-Source Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing sampling hold circuits face challenges in maintaining a constant gate-source voltage for transistors due to leakage currents, which affect the accuracy of analog-digital conversion, especially when the high level period of the sampling clock is prolonged, leading to increased power consumption when using frequency dividers to mitigate this issue.
Innovation Solution
An electronic circuit with a duty ratio control unit that adjusts the duty ratio of the input periodic signal, a transistor, a condenser, and a charge control unit to charge the condenser and apply the voltage between the gate and source of the transistor, ensuring a constant drive voltage by shortening the high level period of the output periodic signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the high level period of the sampling clock is prolonged, then the transistor can be driven adequately, but leakage current causes the gate-source voltage to fluctuate and deteriorates AD conversion accuracy
Solution Approach 1:
The patent applies periodic action by using a sampling clock that alternates between high and low levels to control the bootstrap circuit. The circuit periodically charges the capacitor during low level periods and applies the charging voltage during high level periods, creating a cyclic operation that maintains gate-source voltage. This periodic charging mechanism ensures the transistor receives adequate drive voltage while limiting the high level duration to prevent excessive leakage current accumulation.
2Measurement precision
If the high level period of the sampling clock is shortened to reduce leakage current effects, then AD conversion accuracy is improved, but transistor drive capability becomes insufficient
Solution Approach 1:
The patent implements preliminary action by charging the capacitor during the low level period of the sampling clock before the high level period begins. This advance charging ensures that when the high level period starts, the capacitor is already fully charged and ready to provide the necessary gate-source voltage to the transistor. This preliminary charging action allows the high level period to be short without compromising transistor drive capability, as the voltage is prepared in advance.
3Measurement precision
If a frequency divider is used to shorten the high level period, then leakage current effects are reduced, but power consumption increases due to higher frequency clock requirement
Solution Approach 1:
The patent uses copying by creating an inverted version of the sampling clock signal to control the bootstrap circuit. The inverted clock allows the bootstrap circuit to operate in opposite phase to the main sampling clock, enabling voltage charging during low level periods and application during high level periods. This copying approach eliminates the need for frequency dividers and higher frequency clocks, maintaining the same operating frequency while achieving the desired short high level period effect, thus avoiding increased power consumption.
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
This approach effectively maintains a constant drive voltage for the transistor, reducing the impact of leakage currents and minimizing power consumption by not requiring a higher frequency clock, thus enhancing the accuracy of analog-digital conversion.
Implementation Method 1
a condenser; a charge control unit configured to charge the condenser with a predetermined voltage
Data Source
AI summary
To control a drive voltage of a transistor to be constant in a circuit that captures signals. A duty ratio control unit changes a duty ratio of a predetermined input periodic signal and outputs the predetermined input periodic signal as an output periodic signal. A transistor is a transistor that outputs an input signal input to a source from a drain as an output signal. A charge control unit charges the condenser with a predetermined voltage in a case in which the output periodic signal is not at a specific level. A transistor drive unit applies the charged predetermined voltage between a gate and the source of the transistor in a case in which the output periodic signal is at the specific level.