Current Generator with Noise Subtraction Circuit
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Solution Overview
Problem
Portable devices like smartphones and tablets face power instability due to internal battery discharge, leading to unstable supply voltage, which affects the reliability of circuits requiring stable current/voltage references.
Innovation Solution
A current generator comprising first and second current generation circuits that scale reference currents based on supply voltage ratios, with a current subtracting circuit removing noise from these currents, and an RC filter or transistor-based circuit for residual noise removal, ensuring the output current is stable regardless of supply voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If portable devices operate at low power from internal battery, then energy consumption is reduced, but power stability deteriorates causing supply voltage fluctuations
Solution Approach 1:
The current generation function is divided into multiple independent current generation circuits (first current generation circuit, second current generation circuit, etc.), each generating current with different noise characteristics. By segmenting the current generation into multiple paths, the system can selectively combine or subtract these currents to achieve low-noise output while maintaining low power operation.
Solution Approach 2:
The patent converts the harmful supply voltage fluctuations and noise into a beneficial effect by using differential current subtraction. The first and second current generation circuits generate currents that both contain noise components related to supply voltage changes, but when subtracted, these noise components cancel each other out, leaving a clean reference current that is immune to supply voltage variations.
2Device complexity
If conventional current generation circuits are used, then circuit simplicity is maintained, but current stability deteriorates due to noise from supply voltage changes
Solution Approach 1:
The patent introduces intermediate current generation circuits (first current generation circuit, second current generation circuit) that act as mediators between the noisy supply voltage and the required stable reference current. These intermediate circuits generate currents with known noise characteristics that can be mathematically subtracted to eliminate the noise, serving as a bridge to achieve clean reference current.
Solution Approach 2:
The system uses feedback by continuously monitoring the supply voltage fluctuations and their effect on generated currents. The current subtraction process effectively implements negative feedback where the noise components are detected and cancelled in real-time, ensuring the output reference current remains stable despite supply voltage variations.
Data Source
AI summary
A current generator includes a first current generation circuit configured to generate a first current having a first current noise which depends on a change in a supply voltage, a second current generation circuit configured to generate a second current having a second current noise which depends on the change in the supply voltage, and a current subtracting circuit configured to generate a third current with the first current noise and the second current noise removed by subtracting the second current from the first current.