Self-Calibrating Current Source Error Compensation Circuit
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Solution Overview
Problem
Conventional self-calibrating current sources suffer from errors due to charge injection, parasitic capacitance, and current leakage, leading to inaccuracies in replicated currents, particularly exacerbated by switching effects and semiconductor process errors.
Innovation Solution
An apparatus for error compensation using an imitative self-calibrating current source and an error compensation apparatus, which generates a compensation bias signal by comparing an error bias signal with an ideal bias signal, and applies this signal to correct for errors caused by capacitor leakage and switching effects, thereby improving the accuracy of replicated currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional self-calibrating current sources are used, then the circuit structure is simple, but the accuracy of replicated current deteriorates due to charge injection, parasitic capacitance, and capacitor leakage
Solution Approach 1:
The patent segments the current source system into multiple independent units (first current source, second current source, third current source) with dedicated compensation circuits for each. Each unit has its own storage capacitor and switching network, allowing independent error compensation without affecting other units, thus improving overall accuracy while maintaining modular simplicity
Solution Approach 2:
The patent introduces compensation capacitors and compensation switches as intermediary elements between the main current source components. These intermediaries capture and redirect charge injection effects and parasitic capacitance influences, isolating them from the main current replication path and thereby improving accuracy without fundamentally changing the core circuit structure
2Ease of operation
If switching operations are performed in self-calibrating current sources, then current replication function is achieved, but error in replicated current increases due to charge injection and parasitic capacitance effects
Solution Approach 1:
The patent applies preliminary anti-action by introducing compensation switches that are activated in opposition to the main switching operations. When main switches close and cause charge injection, the compensation switches simultaneously close to inject equal and opposite charge, preemptively canceling the error before it affects the replicated current
Solution Approach 2:
The patent implements feedback mechanisms where the compensation circuits monitor the effects of switching operations on the storage capacitors and automatically adjust compensation signals. The compensation amount is determined based on the observed charge sharing and parasitic effects, creating a closed-loop system that continuously corrects switching-induced errors
3Duration of action of moving object
If storage capacitors are used in self-calibrating current sources, then current sampling and replication are enabled, but accuracy deteriorates due to capacitor current leakage over time
Solution Approach 1:
The patent enables self-service by designing compensation circuits that automatically detect and correct leakage-induced errors without external intervention. The compensation capacitors and switches form self-regulating subsystems that continuously monitor storage capacitor voltage drift due to leakage and apply corrective charge, maintaining accuracy throughout the operational duration
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting the compensation charge amount based on the duration of capacitor storage. As leakage increases over time, the compensation circuit modifies its correction magnitude accordingly, adapting to the changing electrical parameters of the storage capacitors to maintain consistent accuracy across different operational time scales
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
The solution effectively compensates for errors in self-calibrating current sources, enhancing the accuracy of replicated currents while maintaining a low cost, thus addressing the inaccuracies introduced by capacitor leakage and switching effects.
Implementation Method 1
the switch SW101 and the switch SW102 are turned on, and the switch SW103 is turned off. At this time, the current source I100 generates a constant current to the transistor M100. The transistor M100 biases the current value to obtain an appropriate gate-to-source voltage (Vgs), and charges the capacitor C100.
Implementation Method 2
as the switch SW101 may cause a charge injection effect, and parasitic capacitance effect may exist between switches, a charge sharing effect may occur when the switches are turned on.
Implementation Method 3
The gate of the transistor M100 receives charges stored by the capacitor C100 as the gate-to-source voltage (Vgs) of the transistor M100, so as to provide a replicated current.
Data Source
AI summary
An apparatus for error compensation of a self calibrating current source adapted for compensating errors of at least one self calibrating current source. The compensation apparatus includes an imitative self calibrating current source, a current source reference apparatus and an error compensation apparatus. The imitative self calibrating current source is used to simulate the structure of the self calibrating current source to generate an error bias signal as the error of the self calibrating current source. The current source reference apparatus is used to generate an ideal bias signal. The error compensation apparatus generates a compensation bias signal to compensate errors of the self calibrating current source according to the difference of the error bias signal and the ideal bias signal.