Controllable Off-Resistance Noise Filter for Faster Settling
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Solution Overview
Problem
Existing noise filter circuits face challenges with high power consumption, limited headroom due to large current dissipation, and slow settling time due to large transistor off-resistance, which interferes with audio signals and is not suitable for low-voltage applications.
Innovation Solution
A noise filter circuit with a transistor off-resistance control circuit that sets a control voltage for the transistor's off-resistance, allowing it to operate in the sub-threshold region without being directly tied to a reference voltage, using a charge storage component and a body-biasing circuit to control the transistor's off-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If large resistance/capacitance is used in the low-pass filter to achieve low corner frequency, then noise filtering performance is improved, but settling time increases and area consumption increases
Solution Approach 1:
The patent applies dynamics by making the transistor off-resistance controllable and adjustable rather than fixed. The control circuit dynamically adjusts the off-resistance of the transistor based on operational requirements, allowing the filter to adapt between high resistance (for better noise filtering) and lower resistance (for faster settling), thus resolving the contradiction between noise filtering performance and settling time
Solution Approach 2:
The patent changes the resistance parameter of the transistor by controlling its off-resistance through a dedicated control circuit. By adjusting the control voltage applied to the transistor, the off-resistance can be varied to optimize both noise filtering and settling time performance, directly addressing the contradiction between these two parameters
2Object-affected harmful factors
If large resistance/capacitance is used in the low-pass filter to achieve low corner frequency, then noise filtering performance is improved, but area consumption increases
Solution Approach 1:
The patent changes the resistance parameter of the transistor by controlling its off-resistance through a dedicated control circuit. By adjusting the control voltage applied to the transistor, the off-resistance can be varied to optimize both noise filtering and settling time performance, directly addressing the contradiction between these two parameters
3Object-affected harmful factors
If transistor off-resistance is large, then noise filtering is improved, but settling time increases
Solution Approach 1:
The patent applies dynamics by making the transistor off-resistance controllable and adjustable rather than fixed. The control circuit dynamically adjusts the off-resistance of the transistor based on operational requirements, allowing the filter to adapt between high resistance (for better noise filtering) and lower resistance (for faster settling), thus resolving the contradiction between noise filtering performance and settling time
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 solution reduces transistor off-resistance, improving settling time, reducing power consumption, and enhancing compatibility with low-voltage applications while minimizing voltage mismatch and tone interference.
Implementation Method 1
The filter includes a first transistor and a charge storage component
Implementation Method 2
The first transistor is arranged to have off-resistance when turned off or operated under sub-threshold region
Data Source
AI summary
A noise filter circuit includes a filter and a transistor off-resistance control circuit. The filter includes a first transistor and a charge storage component. The first transistor has off-resistance when turned off or operated under sub-threshold region. A control terminal of the first transistor is not directly tied to a reference voltage, and is used to receive a first control voltage. The charge storage component has one terminal coupled to a connection terminal of the first transistor. The transistor off-resistance control circuit is coupled to the first transistor, and arranged to set the first control voltage for controlling the off-resistance of the first transistor.