Switched-Capacitor Amplifier Damping for Feed-Forward Peaks
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Solution Overview
Problem
Switched-capacitor amplifiers experience an undesirable feed forward effect at the beginning of the amplification phase, leading to an initial signal peak in the opposite direction, which requires additional correction from the operational amplifier, resulting in increased power and noise performance issues.
Innovation Solution
A damping means is connected to the forward path only at the beginning of the amplification phase, specifically designed to attenuate the signal peak caused by the feed forward effect, using a switch controlled by a control signal, which can be a capacitor or a bypass path, to reduce the slew requirements and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a conventional switched-capacitor amplifier is used, then the circuit can operate with standard power consumption, but an undesirable signal peak occurs at the beginning of the amplification phase due to feed forward effect
Solution Approach 1:
A damping network is introduced as an intermediary element connected between the output terminal and the inverting input terminal. This damping network acts as a mediator that selectively attenuates the harmful signal peak caused by feed forward effect while preserving the normal amplification function. The damping network includes a damping capacitor and damping switch that are activated only during the amplification phase to suppress the unwanted peak.
Solution Approach 2:
The damping network is activated periodically only during the amplification phase through clock signal control of the damping switch. This periodic activation ensures that damping is applied exactly when needed (at the beginning of amplification phase when feed forward effect occurs) while remaining inactive during sampling phases, thus eliminating the signal peak without continuously affecting circuit operation.
2Measurement precision
If the operational amplifier is designed with larger current and bandwidth to correct the feed forward effect, then the signal accuracy is improved, but power consumption and noise performance deteriorate
Solution Approach 1:
The harmful feed forward effect that causes signal peak is converted into a beneficial damping action. By introducing the damping network that exploits the same feed forward path, the unwanted peak is transformed into a controlled damping effect that actively suppresses the signal peak. The damping capacitor and switch are configured to create a negative feedback path that counteracts the feed forward effect, turning the problem into a solution.
Solution Approach 2:
The damping network changes the effective impedance parameters dynamically during operation. During the amplification phase, the damping switch closes to connect the damping capacitor, altering the feedback network parameters to provide additional damping. This parameter change allows the circuit to achieve better signal accuracy without requiring increased operational amplifier current or bandwidth.
3Measurement precision
If a larger load capacitance is used to circumvent the feed forward effect, then signal accuracy is improved, but the operational amplifier speed decreases and power consumption increases
Solution Approach 1:
Instead of uniformly increasing the entire load capacitance, the damping network applies localized damping only to the specific feed forward path causing the signal peak. The damping capacitor is connected in parallel with the feedback capacitor, creating a localized damping effect precisely where the feed forward effect occurs (at the feedback path), without affecting the overall load capacitance value that determines amplifier speed.
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
The proposed solution effectively reduces the signal peak at the beginning of the amplification phase without affecting the power consumption or speed of the circuit, allowing for the design of switched-capacitor circuits with lower current and noise requirements for a given speed, with significant improvements in slew requirements and power-speed-noise trade-off.
Implementation Method 1
A forward path is connected, on an input side, to the signal input and connected, on an output side, to the signal output. The forward path comprises at least one switched capacitor controlled by a clock signal.
Implementation Method 2
a damping means is connected to the forward path, the damping means being designed for attenuation of a signal peak at the beginning of the amplification phase
Data Source
AI summary
A switched-capacitor amplifier arrangement and a method to amplify a signal are presented. A forward path has at least one switched capacitor (10) controlled by a clock signal, thus providing an amplification phase (1) of the forward path and an additional clock phase (2). A damping means (22) is connected to the forward path, the damping means being designed for attenuation of the signal peak at the beginning (2p) of the amplification phase. This avoids an undesired feed forward effect at the beginning of the amplification phase of an SC circuit.