Bus Node Receiver Circuit for Weak Signal Detection Under Noise
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Solution Overview
Problem
EIB network receivers face challenges in achieving optimal sensitivity, dynamics, and immunity to interference while maintaining overload-proof functionality and adapting output levels to connected control units, due to signal attenuation and noise issues in bus networks.
Innovation Solution
A receiver design incorporating a differential amplifier with a comparator function, utilizing a feedback resistor to stabilize behavior and a current mirror to prevent overloading, along with a voltage source that maintains signal voltage relation and reference voltage, and a Schmitt trigger-like circuit to set and maintain functional tolerance limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the receiver is designed to detect weak attenuated signals, then sensitivity is improved, but the receiver becomes vulnerable to noise and interference
Solution Approach 1:
The patent implements a feedback mechanism where the output of the differential amplifier is fed back to its input through a feedback resistor. This feedback stabilizes the operating point of the amplifier, improves linearity, and reduces the impact of noise and interference by continuously adjusting the input based on the output signal quality.
Solution Approach 2:
The patent introduces an intermediary Schmitt trigger circuit between the differential amplifier and the control unit. This Schmitt trigger acts as a mediator that cleans up the signal by providing hysteresis, eliminating noise-induced false transitions, and ensuring clean digital output levels that are immune to small noise variations.
2Reliability
If the receiver is designed to handle high signal levels, then overload protection is improved, but the receiver loses sensitivity to weak signals
Solution Approach 1:
The patent employs a differential amplifier with dynamically adjustable operating characteristics through feedback. The feedback resistor creates a dynamic response where the amplifier automatically adapts its gain and operating point based on the input signal level, allowing it to handle both weak and strong signals without saturation or loss of sensitivity.
Solution Approach 2:
The patent changes the operating parameters of the receiver circuit by using a differential amplifier configuration with feedback that allows the effective gain and threshold levels to vary with signal conditions. This parameter adaptation enables the receiver to maintain optimal performance across a wide dynamic range of input signal levels.
3Reliability
If a differential amplifier with bipolar technology is used, then comparator function and hysteresis are achieved, but circuit complexity and sensitivity to component variations increase
Solution Approach 1:
The patent makes the differential amplifier circuit universal by designing it to perform multiple functions: signal amplification, comparison, hysteresis generation, and overload protection. The feedback mechanism enables the same circuit to adapt its behavior based on signal conditions, reducing the need for separate dedicated circuits for each function.
Solution Approach 2:
The differential amplifier circuit serves itself by using its own output signal to generate the reference voltage and hysteresis through the feedback resistor. This self-service mechanism eliminates the need for external reference voltage sources and complex biasing circuits, simplifying the overall design while maintaining stable comparator functionality.
4Measurement precision
If the output signal level is increased to improve signal-to-noise ratio, then detection sensitivity is improved, but the control unit input voltage limit is exceeded
Solution Approach 1:
The feedback resistor creates a voltage divider effect that automatically limits the output voltage level. When the differential amplifier output tries to exceed the control unit's voltage limit, the feedback mechanism adjusts the operating point to prevent overvoltage, thereby protecting the control unit while maintaining adequate signal levels for reliable detection.
Solution Approach 2:
The circuit incorporates beforehand cushioning by designing the feedback network to preemptively limit voltage excursions before they can reach dangerous levels. The feedback resistor and associated circuitry are configured to clamp the output voltage within safe limits for the control unit, preventing damage before it can occur.
Data Source
Figure 1(a)~2
Figure 3
AI summary
The invention relates to a receiver in a bus node of a bus network, in particular an EIB network, said bus node being coupled to a bus line (Bus+, Bus-) that provides the receiver with a signal formed from bit pulses, comprising a differential amplifier (Q1A, Q1B, Q2A, Q2B), which has a first input (E1) and a second input (E2) and at least one output (RxD), characterized in that a reference voltage (Uref) is present at the first input (E1) and a voltage carrying the signal is present at the second input (E2), the voltage carrying the signal being designed in such a way that a signal appears at the output (RxD) only if the absolute value of the voltage at the second input (E2) is greater than the absolute value of the reference voltage (Uref) at the first input.