Parallel Cancellation Path for Analog Circuit Distortion
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Solution Overview
Problem
Conventional techniques fail to adequately reduce distortion in analog circuits due to non-linear current flow through source impedance, which affects the performance of analog-to-digital converters and other analog systems.
Innovation Solution
An integrated circuit design with a cancellation path in parallel to the main path, generating a cancelling non-linear current to counteract the non-linear current drawn by the input impedance, thereby reducing distortion by ensuring a net zero non-linear current flows through the source impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional techniques (gate bootstrapping, back-gate bootstrapping, buffering) are used to reduce non-linear current, then distortion is partially reduced, but the distortion cannot be adequately eliminated and device complexity increases
Solution Approach 1:
The invention generates an equal and opposite non-linear current through the cancellation path to cancel the harmful non-linear current from the main path. By converting the harmful non-linear current into a beneficial cancelling current, the distortion is reduced without requiring complex buffering or multiple bootstrapping circuits.
Solution Approach 2:
The invention divides the current path into two separate paths: a main path that carries the signal current and a cancellation path that carries the cancelling non-linear current. This segmentation allows independent optimization of each path and simplifies the overall circuit design compared to conventional techniques that require multiple switches and bootstrapping circuits.
2Object-affected harmful factors
If source impedance is reduced to minimize non-linear current, then distortion decreases, but the performance of pipelined ADCs deteriorates as source impedance must be maintained for proper operation
Solution Approach 1:
The invention introduces a cancellation path as an intermediary that generates a cancelling current to offset the non-linear current. This allows the source impedance to remain at its required value for ADC operation while the harmful non-linear effects are cancelled by the intermediary cancellation path.
Solution Approach 2:
The invention extracts the non-linear current component from the main signal path by routing it through a separate cancellation path where it is cancelled. This separates the harmful non-linear current effect from the main signal, allowing the source impedance to maintain its required value for ADC performance.
3Object-affected harmful factors
If input impedance of sampling circuit is increased to reduce non-linear current, then distortion is reduced, but the sampling network cannot adequately control the distortion generated by external source impedance
Solution Approach 1:
The cancellation path is configured to generate a cancelling current that is equal and opposite to the non-linear current in the main path. This feedback mechanism actively compensates for distortion regardless of the source impedance value, giving the sampling network control over distortion that was previously determined by external components.
Solution Approach 2:
The invention converts the uncontrollable non-linear current from external source impedance into a controllable cancelling current through the cancellation path. By generating an equal and opposite current, the system gains control over distortion that was previously determined by external components outside the die.
Data Source
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AI summary
Embodiments of the present invention may provide an improved apparatus and method for reducing distortion in analog circuits. A circuit in accordance with the present invention may include a main path comprising an analog circuit with an input impedance, a source impedance representing the impedance of an input network driving the analog circuit, and a cancellation path. The cancellation path may be in parallel to the main path and may generate a cancelling non-linear current to substantially cancel a non-linear current drawn to the input impedance, resulting in a decrease of non-liner current flowing through the source impedance.