Amplifying Circuit for Baseline Cancellation and Fast Common-Mode Feedback
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Solution Overview
Problem
Conventional amplifying circuits face challenges in eliminating baseline signals and matching common-mode voltages between pre-stage and post-stage circuits, leading to offset voltage issues and increased power consumption due to slow common-mode negative feedback establishment.
Innovation Solution
The proposed amplifying circuit includes a reference voltage generating circuit, common-mode voltage conversion circuit, and common-mode negative feedback circuit to generate a reference common-mode voltage matching the post-stage circuit, eliminate baseline signals, and quickly establish common-mode negative feedback using a Correlated Double Sampling fully differential programmable gain amplifying circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a conventional switched capacitor common-mode negative feedback circuit is used, then the common-mode voltage can be stabilized, but the establishment time is long and power consumption increases
Solution Approach 1:
The patent applies preliminary action by pre-establishing the common-mode voltage through a dedicated common-mode voltage generation circuit before the main amplification operation begins. This allows the common-mode voltage to be ready in advance, eliminating the need for slow feedback establishment during signal processing, thus resolving the contradiction between stability and establishment time.
2Device complexity
If the common-mode voltage of pre-stage circuit does not match the programmable gain amplifier, then circuit design is simplified, but offset voltage changes and input common-mode point shifts occur
Solution Approach 1:
The patent introduces a common-mode voltage conversion circuit as an intermediary between the pre-stage circuit and the programmable gain amplifier. This conversion circuit acts as a mediator that transforms the common-mode voltage level to match between stages, preventing offset voltage changes and common-mode point shifts while maintaining reasonable circuit design complexity.
3Ease of operation
If the baseline signal is not eliminated, then circuit operation is straightforward, but the programmable gain amplifier enters saturation due to the large baseline signal
Solution Approach 1:
The patent extracts and removes the baseline signal from the input signal before amplification using a baseline elimination circuit. By separating and eliminating the large baseline component, the circuit prevents amplifier saturation while maintaining straightforward operation, as the elimination is performed automatically by the circuit architecture without complex control.
4Device complexity
If the common-mode voltage is not converted between stages, then circuit design is simpler, but the post-stage circuit cannot work normally
Solution Approach 1:
The common-mode voltage conversion circuit serves as an intermediary that bridges the voltage level mismatch between pre-stage and post-stage circuits. It converts the common-mode voltage to the appropriate level for the post-stage circuit, ensuring normal operation while keeping the overall design manageable through modular implementation.
Data Source
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AI summary
The present application provides an amplifying circuit comprising a reference voltage generating circuit, a common-mode voltage conversion circuit, a common-mode negative feedback circuit, and an amplifying sub-circuit. The reference voltage generating circuit generates a first reference voltage, a second reference voltage, and a reference common-mode voltage according to a post-stage common-mode voltage, the common-mode voltage conversion circuit converts the pre-stage output differential signal into a differential input signal according to the reference common-mode voltage, the common-mode negative feedback circuit generates a control voltage to quickly establish a common-mode negative feedback of the amplifying sub-circuit, wherein the first reference voltage and the second reference voltage are used to cancel a baseline signal of the pre-stage output differential signal. The amplifying circuit provided in the present application can eliminate the baseline signal, convert the common-mode voltage and quickly establish the common-mode negative feedback.