Single-Ended to Differential Converter Without Filter Settling Delay
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Solution Overview
Problem
Existing test systems face challenges in accurately and efficiently converting single-ended signals to differential signals, particularly in scenarios where test instruments designed for differential signals need to interface with units using single-ended signals, such as optical signals from MIL-STD-1773 buses.
Innovation Solution
A converter system that includes a high pass filter to remove DC components and generate a midpoint value, which is used as an offset to create differential output signals through non-inverting and inverting amplifiers, allowing for accurate and quick conversion of single-ended signals to differential signals without waiting for the filter to settle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high pass filter is used to remove DC components and generate midpoint value, then the differential output signal accuracy is improved, but the filter settling time causes measurement delay
Solution Approach 1:
The patent applies preliminary action by capturing the midpoint value of the filtered signal before the filter has fully settled. The circuit captures this intermediate midpoint value and uses it to generate the differential output signal, eliminating the need to wait for filter settling while maintaining measurement accuracy.
2Measurement precision
If the converter waits for filter settling before measurement, then measurement accuracy is improved, but testing speed is reduced
Solution Approach 1:
The circuit performs preliminary capture of the midpoint value at the appropriate moment during filter operation, enabling accurate differential signal generation without waiting for complete filter settling, thus maintaining both accuracy and speed
Solution Approach 2:
The patent skips the traditional filter settling wait time by rushing through the measurement process using the captured midpoint value, achieving accurate results faster than conventional methods would allow
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
Enables accurate and rapid measurement of single-ended signals by eliminating errors introduced during filter settling, facilitating quick and precise testing in high-speed environments with minimal delay.
Implementation Method 1
an AC coupling circuit configured to generate the filtered single-ended signal in response to receiving the single-ended signal
Implementation Method 2
A decay block generates a signal representing a midpoint value of the filtered single-ended signal. The decay block may be configured to provide an output signal decaying at a rate that substantially matches a rate of change of the midpoint value
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A single ended to a differential signal converter. The single ended signal is passed through a high pass filter to block DC components. A positive and a negative version of the filtered signal are used collectively as the differential output of the converter. To allow accurate measurements on the input signal without waiting for the output of the high pass filter to settle, the differential outputs are offset by a dynamically generated signal representative of the midpoint of the filtered signal. That offset is generated by capturing a value representing the midpoint when a signal is first applied. This captured value is allowed to change with a time constant matching a time constant of the high pass filter. The converter may be used to connect a test instrument to a unit under test that generates test signals in a format that the test instrument is not specifically configured to measure.