Track-and-Hold Circuit Layout for Kick-Back Noise Isolation
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Solution Overview
Problem
Track and hold circuits in wireless receiving systems suffer from kick-back noise and signal distortion due to charge injection from switches, affecting the signal-to-noise ratio and distortion ratio of base-band signals.
Innovation Solution
A track and hold circuit design incorporating a gain control circuit, operational amplifier, and capacitors, where resistors and switches are used to selectively provide resistance and control gain, isolating charge injections and eliminating switching elements between capacitors and operational amplifier terminals, thereby suppressing kick-back noise and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switches are used to control track and hold operation, then the track and hold circuit can track and hold the down converted intermediate frequency signal, but charge injection from the switches generates kick-back noise affecting the front-end stage and back-end stage
Solution Approach 1:
The patent introduces resistors as intermediary elements between the switches and the operational amplifier. These resistors act as isolation barriers that prevent charge injection from the switches from directly affecting the operational amplifier and generating kick-back noise, while still allowing the switches to control the track and hold operation effectively.
Solution Approach 2:
The patent extracts the harmful charge injection effect from the switching operation by using resistors to isolate the charge injection source (switches) from the sensitive components (operational amplifier). This separation allows the switching function to be maintained while removing its harmful side effect.
2Ease of operation
If switches are used to control track and hold operation, then the circuit can function, but charge injection introduces distortion upon the track signal and corresponding digital signal
Solution Approach 1:
Resistors are introduced as intermediary elements between the switches and the signal path. These resistors isolate the charge injection from the switches, preventing it from distorting the track signal and digital signal, while maintaining the ease of operational control through the switches.
3Productivity
If kick-back noise is present in the track and hold circuit, then the circuit operates, but the signal-to-noise ratio of the base-band signal is degraded
Solution Approach 1:
The resistors serve as intermediary elements that block the propagation of kick-back noise from the switching operation to the operational amplifier and subsequent signal processing stages, thereby maintaining the circuit's operational productivity while preserving the signal-to-noise ratio.
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 solution effectively reduces kick-back noise and improves signal quality by isolating charge injections and eliminating distortion, enhancing the signal-to-noise ratio of base-band signals in wireless receiving systems.
Implementation Method 1
The operational amplifier is arranged to generate an output signal according to the input signal and the gain value
Implementation Method 2
The first capacitor is arranged to hold the output signal between a first input terminal and a first output terminal of the operational amplifier
Implementation Method 3
a first resistor-based network arranged to selectively provide a first resistance between a first signal receiving terminal receiving the input signal and the first input terminal of the operational amplifier
Data Source
AI summary
An operational circuit includes: a gain control circuit arranged to provide a gain value upon an input signal according to a set of control signals, wherein the gain control circuit includes a first resistor-based network and a second resistor-based network; an operational amplifier coupled to the gain control circuit and arranged to generate an output signal according to the input signal and the gain value; and a first capacitor coupled to the operational amplifier and arranged to hold the output signal between a first input terminal and a first output terminal of the operational amplifier, wherein when the operational circuit is operating, a first terminal of the first capacitor is consistently coupled to the first input terminal of the operational amplifier, and a second terminal of the first capacitor is consistently coupled to the first output terminal of the operational amplifier.