Input Circuit Variable Voltage Drop Transistor
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Solution Overview
Problem
Existing semiconductor input circuits face challenges in handling a wide range of differential signal voltages, leading to larger transistor sizes that result in slower switching speeds and varying output voltages, which limits signal resolution and accuracy.
Innovation Solution
The implementation of a common mode input circuit using a P-channel transistor and a variable voltage drop device, where a drain/source voltage detector controls the variable voltage drop device to maintain a constant output voltage across varying input signal voltages, ensuring the transistor operates effectively across different voltage levels without compromising speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If input transistors are sized large to receive the largest expected voltage, then the circuit can handle a wide range of input voltages, but switching speeds become slower
Solution Approach 1:
The patent implements a variable voltage drop device that dynamically adjusts its voltage drop based on the detected input common mode voltage level. This dynamic adjustment allows the input transistor to operate at optimal conditions across different voltage ranges without requiring oversized dimensions, thereby maintaining fast switching speeds while handling wide voltage variations from 0.2V to 1.5V common mode inputs
2Adaptability or versatility
If common mode input voltage varies, then the circuit can interface with different wireless products, but output voltage varies which limits signal range and accuracy
Solution Approach 1:
The patent employs a feedback mechanism where a drain/source voltage detector continuously monitors the input common mode voltage level and provides feedback to the variable voltage drop device. This feedback loop enables the system to automatically adjust the voltage drop to compensate for input variations, thereby maintaining a constant output voltage level that preserves full signal range and measurement precision across different input voltage conditions
Solution Approach 2:
The patent changes the operating parameters of the voltage drop device based on the detected input voltage level. By adjusting the voltage drop parameter dynamically according to the input common mode voltage, the system maintains consistent output characteristics despite varying input conditions, ensuring full signal resolution and accuracy for interfacing with diverse wireless products
Data Source
AI summary
An input voltage circuit comprises an input transistor having a control electrode for receiving a variable input voltage, a voltage detection transistor having a current electrode coupled to a current electrode of the input transistor forming a first node, and a current source coupled to a second current electrode of the voltage detection transistor forming a second node. The input voltage circuit further comprises a variable voltage drop transistor having a first current electrode coupled to the first node, a control electrode coupled to the second node and a second current electrode coupled to an output node, wherein the voltage detection transistor detects a variation in the variable input voltage and provides a signal to the variable voltage drop transistor. The variable voltage drop transistor generates a voltage drop proportional to the variation in the variable input voltage to ensure a substantially constant output at the output node.