Pseudo-Differential Switched-Capacitor CM Stabilization
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Solution Overview
Problem
Pseudo-differential switched-capacitor circuits face challenges in stabilizing common-mode voltage due to charge injection effects from switches, leading to performance degradation and increased power consumption in low operating voltage environments.
Innovation Solution
An integrator-based common-mode stabilization technique is employed, utilizing differential floating sampling to bypass input common-mode disturbances and sense errors, forming a common-mode negative feedback loop to stabilize the output voltage level, thereby reducing charge injection effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If pseudo-differential amplifier is used to eliminate tail current transistor, then output signal range is enlarged, but common-mode noise immunity is lost
Solution Approach 1:
The patent implements a common-mode feedback circuit that senses the output common-mode voltage and adjusts the bias conditions to maintain stable common-mode operation. This feedback mechanism compensates for the loss of common-mode noise immunity by actively regulating the common-mode voltage level, allowing the pseudo-differential amplifier to operate with enlarged signal range while maintaining noise rejection capability.
2Object-affected harmful factors
If fully differential amplifier with CMFB is used, then common-mode noise immunity is improved, but output signal range is limited by tail current transistor
Solution Approach 1:
The patent extracts and removes the tail current transistor from the differential amplifier structure, transitioning to a pseudo-differential configuration. This extraction eliminates the constraint on output signal range that the tail current transistor imposed, while the common-mode feedback circuit is added to compensate for the lost common-mode rejection capability.
3Use of energy by moving object
If low operating voltage is used to improve circuit performance, then power consumption is reduced, but signal range is limited and design complexity increases
Solution Approach 1:
The patent changes the operational parameters by implementing a pseudo-differential configuration with common-mode feedback that is specifically optimized for low-voltage operation. The circuit uses switched-capacitor techniques and precise biasing schemes that enable stable operation at low supply voltages while maintaining adequate signal range, thereby achieving low power consumption without excessive design complexity.
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 reduces common-mode voltage drift and power consumption, maintaining signal integrity and performance in low-voltage operations without the need for additional active circuits.
Implementation Method 1
An integrator is employed to sense the total output common-mode disturbance and feed back its output cmi to the switched-capacitor circuit with the DFS technique, thereby stabilizing output common-mode level at a desirable level
Implementation Method 2
differential floating sampling to bypass input common-mode disturbances and sense errors
Data Source
AI summary
A pseudo-differential switched-capacitor circuit using integrator-based common-mode stabilization technique is disclosed. A pseudo-differential switched-capacitor circuit with the differential floating sampling (DFS) technique has a common-mode gain value of one (1). An integrator is electrically coupled to the differential positive/negative outputs of the DFS circuit, and the integrator feeds back integrator output to the DFS circuit by detecting common-mode voltage disturbance at the differential positive output (Vout+) and negative output (Vout−), thereby stabilizing output common-mode level of the differential positive output (Vout+) and negative output (Vout−) at a desirable level.