Low Frequency Signal State Detection Circuit
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Solution Overview
Problem
Existing detection techniques find it difficult to accurately distinguish between different states of communication signals, such as idle, low frequency, and high frequency states in communication standards like USB 2.0 and USB 3.0, which hinders effective communication and power management.
Innovation Solution
A method and device that filter differential communication signals using low pass filters and compare them with an internal reference voltage to generate a low frequency detect signal, accurately identifying whether a communication signal is in a low frequency state, idle state, or high frequency state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing detection techniques are used, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The detection circuit is segmented into specialized sub-circuits: a low frequency detect circuit with low pass filters and comparators for detecting low frequency states, and a high frequency detect circuit for detecting high frequency states. Each segment handles specific frequency ranges, improving overall detection precision while keeping individual segments relatively simple.
Solution Approach 2:
Low pass filters are introduced as intermediary components between the differential communication signal input and the comparators. These filters mediate the signal by attenuating high frequency components before comparison, enabling accurate low frequency state detection without requiring the entire detection system to be complex.
2Measurement precision
If low pass filters and comparators are added for precise detection, then measurement precision improves, but device complexity increases
Solution Approach 1:
The low pass filters and comparators are designed to serve multiple functions: they detect low frequency states by comparing filtered signals against reference voltages, and they also help distinguish idle states from low frequency states. This multi-functionality reduces the need for additional separate components, balancing precision improvement with controlled complexity.
Solution Approach 2:
The detection circuit utilizes parameter changes in the communication signal (frequency, voltage levels) to identify different states. By monitoring voltage thresholds and frequency characteristics through the filters and comparators, the circuit achieves precise state detection by exploiting natural signal parameter variations rather than requiring complex processing.
3Measurement precision
If differential signal filtering is implemented, then measurement precision improves, but loss of information increases
Solution Approach 1:
The low pass filters extract only the low frequency components of the differential communication signal that are relevant for state detection, while intentionally removing high frequency components. This extraction approach prevents information loss about the actual state being detected (low frequency vs. idle), as the high frequency components are not needed for this specific detection function.
Solution Approach 2:
Different parts of the signal processing path have different quality requirements. The low pass filters apply local quality control by preserving low frequency signal characteristics while attenuating high frequency components. This localized filtering approach maintains detection precision for the intended purpose without requiring perfect preservation of all signal components.
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 precise detection of communication signal states, improving communication efficiency and power management by effectively distinguishing between low frequency, idle, and high frequency states, thereby facilitating better device initialization and data transfer.
Implementation Method 1
filtering the positive portion of the communication signal through a first low pass filter to provide a filtered positive portion of the communication signal
Implementation Method 2
comparing the filtered positive portion of the communication signal with an internal reference voltage
Data Source
AI summary
Various techniques are provided to detect a state of a communication signal. In one example, a method of detecting a state of a signal includes receiving a differential communication signal comprising a positive portion and a complementary negative portion. The method also includes filtering the positive portion of the communication signal through a first low pass filter to provide a filtered positive portion of the communication signal. The method also includes filtering the negative portion of the communication signal through a second low pass filter to provide a filtered negative portion of the communication signal. The method also includes comparing the filtered positive portion of the communication signal with an internal reference voltage. The method also includes comparing the filtered negative portion of the communication signal with the internal reference voltage. The method also includes generating a low frequency detect signal in response to the comparing operations to indicate whether the communication signal is in a low frequency state.