Charge Transfer Circuit Error Correction
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Solution Overview
Problem
The accuracy of charge transfer circuits is compromised by fluctuations in transistor threshold voltage and offset voltages, leading to errors in charge transfer, particularly due to variations in process conditions, power supply voltage, and operating temperature.
Innovation Solution
A charge transfer circuit with an error sensing circuit to detect voltage fluctuations and an error correction unit to eliminate errors in the output voltage by using a CMOS transfer gate and digital signal processing to calculate and correct the error components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charge transfer is performed using a transistor as a charge transfer element, then charge transfer functionality is achieved, but threshold voltage fluctuations cause transfer accuracy to deteriorate
Solution Approach 1:
The patent introduces a feedback mechanism where the voltage at the first node (which reflects threshold voltage variations) is detected and used to generate a correction signal. This correction signal is fed back to adjust the charge transfer process, compensating for threshold voltage fluctuations and maintaining transfer accuracy despite transistor parameter variations.
Solution Approach 2:
The patent dynamically adjusts operating parameters based on detected variations. Specifically, the voltage applied to the gate of the charge transfer transistor is modified according to the detected threshold voltage changes, allowing the system to adapt to parameter drift and maintain accurate charge transfer performance.
2Productivity
If a differential amplifier is used for charge transfer, then charge transfer capability is improved, but offset voltage causes transfer accuracy to deteriorate
Solution Approach 1:
The patent employs feedback by detecting the offset voltage through the first node voltage and generating a correction signal that compensates for the offset. This feedback mechanism allows the system to maintain high transfer efficiency while correcting accuracy errors caused by the differential amplifier's offset voltage.
Solution Approach 2:
The patent introduces an intermediary correction circuit that measures the offset voltage effect and generates a compensating signal. This intermediary mechanism separates the high-speed transfer function from the precision correction function, allowing the differential amplifier to operate efficiently while the correction circuit eliminates its inherent inaccuracies.
3Measurement precision
If error correction circuits are added to eliminate voltage fluctuations, then transfer accuracy is improved, but circuit complexity increases
Solution Approach 1:
The patent designs the error sensing and correction circuitry to serve multiple functions. The same circuit nodes and components used for charge transfer are also utilized for error detection and correction, reducing the need for entirely separate correction circuits and thereby limiting the increase in overall system complexity.
Solution Approach 2:
The circuit uses its own internal nodes (specifically the first node voltage) to detect errors and generate correction signals, rather than requiring entirely external correction systems. This self-service approach allows accuracy improvement while minimizing additional circuit complexity by leveraging existing circuit elements.
Data Source
AI summary
A charge transfer circuit has a charge transfer unit including an input charge holding element holding an input charge, an output charge holding element holding an output charge, and a charge transfer element, provided between a first node of the input charge holding element and a second, node of the output charge holding element, to transfer the charge held by the input charge holding element to the output charge holding element, an error sensing circuit detecting a third voltage corresponding to a first voltage of the first node when the charge transfer element finished transferring the charge from the input charge holding element to the output charge holding element, and an error correction unit correcting a second voltage of the second node when the charge transfer finished based on the third voltage and eliminate an error included in the second voltage of the second node.