Track-and-Hold Circuit Compensation for Low Harmonic Distortion
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Solution Overview
Problem
High-speed analog-to-digital converters (ADCs) face performance limitations due to harmonic distortion in their track-and-hold circuits, which affect the accuracy of digital signal conversion.
Innovation Solution
The introduction of a second capacitor with a first terminal connected to the resistor and a second terminal connected to a power supply terminal, which reduces frequency-dependent harmonic distortion by providing a low impedance path for charge discharge during the sampling phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a feedback connection is used to reduce excess currents flowing onto the hold capacitor, then current management is improved, but harmonic distortion remains and adversely affects ADC performance
Solution Approach 1:
A compensation capacitor is introduced as an intermediary element connected between the tracking voltage node and the hold capacitor node. This capacitor mediates the charge transfer process by providing an additional path for charge compensation, thereby reducing harmonic distortion while maintaining improved current management from the feedback connection.
Solution Approach 2:
The invention changes the electrical parameters of the track-and-hold circuit by adding the compensation capacitor, which modifies the charge-discharge characteristics and voltage transfer function. This parameter change enables the circuit to compensate for non-linearities and reduce harmonic distortion in the ADC conversion process.
2Productivity
If the track-and-hold circuit operates at high speed, then conversion rate is improved, but harmonic distortion increases and adversely affects performance
Solution Approach 1:
The compensation capacitor is pre-charged during the tracking phase to anticipate and compensate for charge deficiencies that would occur during the hold phase. This preliminary action prepares the circuit in advance, allowing high-speed operation without introducing harmonic distortion that would normally arise from inadequate charge compensation.
Solution Approach 2:
The compensation capacitor acts as a mediator that smooths the charge transfer between the tracking and hold phases, enabling high-speed operation while maintaining signal integrity and minimizing harmonic distortion generation.
3Device complexity
If conventional track-and-hold circuit design is used, then circuit simplicity is maintained, but harmonic distortion adversely affects ADC performance
Solution Approach 1:
Rather than redesigning the entire track-and-hold circuit, the invention applies a localized modification by adding a single compensation capacitor at a specific node. This local quality change provides harmonic distortion compensation while preserving the overall simplicity and conventional design of the circuit.
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 configuration significantly reduces harmonic distortion, improving the overall performance of the track-and-hold circuit and enhancing the accuracy of the digital output signal.
Implementation Method 1
A second capacitor is provided, having a first terminal connected to the first terminal of the resistor and having a second terminal connected to a power supply terminal. The second capacitor substantially reduces frequency-dependent harmonic distortion.
Data Source
AI summary
A track-and-hold circuit capable of tracking an analog input signal and holding a sampled voltage of the analog input signal at a sampling instant for processing by other circuitry, in response to a track signal that alternates with a hold signal. A first capacitor is provided, having a first terminal connected to a power supply terminal. Tracking circuitry operates when in an on state to apply through a resistor a tracking voltage to a second terminal of the first capacitor that corresponds to the voltage of the analog input signal, by applying the tracking voltage to a first terminal of the resistor, the second terminal of the resistor being connected to the second terminal of the first capacitor. A switch, responsive to the track signal and the hold signal, operates to switch the tracking circuitry to an on state in response to the track signal and to an off state in response to the hold signal, the time of change from the track signal to the hold signal comprising the sampling instant. A second capacitor is provided, having a first terminal connected to the first terminal of the resistor and having a second terminal connected to a power supply terminal. The second capacitor substantially reduces frequency-dependent harmonic distortion.