Bias Current Generator Calibration for Semiconductor Process Variations
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Solution Overview
Problem
Semiconductor devices face challenges in generating currents and voltages with reduced complexity and cost, as process variations during fabrication affect the operating characteristics of components, requiring calibration to compensate for these variations.
Innovation Solution
A semiconductor device incorporating a voltage generator, reference current generators, a non-volatile memory for storing calibration codes, and bias current generators that adjust currents based on these codes to generate relative and absolute currents, thereby reducing complexity and fabrication costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If calibration is performed to compensate for process variations, then operating characteristics consistency is improved, but device complexity increases
Solution Approach 1:
The patent performs calibration during the fabrication process itself, storing calibration codes in non-volatile memory before the device is shipped. This preliminary calibration action eliminates the need for complex post-manufacturing calibration systems, as the calibration data is already embedded in the device. The calibration codes compensate for process variations that occur during fabrication, ensuring consistent operating characteristics without requiring complex runtime calibration mechanisms.
Solution Approach 2:
The patent creates a simplified copy of the calibration information by storing only the essential calibration codes in non-volatile memory, rather than implementing complex calibration circuits. These calibration codes serve as a compact representation that enables current generators to compensate for process variations through simple lookup and application of pre-determined correction values, significantly reducing the complexity of the calibration system.
2Adaptability or versatility
If multiple current generators are used to provide both relative and absolute currents, then functionality is improved, but device complexity increases
Solution Approach 1:
The patent implements a universal current generator architecture where a single current generator circuit can operate in multiple modes by applying different calibration codes. The same hardware infrastructure generates both relative currents (which track process variations) and absolute currents (which are compensated for process variations) by simply changing the calibration code applied. This multi-functionality eliminates the need for separate dedicated circuits for each current type, reducing overall device complexity while maintaining full functionality.
3Duration of action of stationary object
If calibration codes are stored in non-volatile memory, then calibration data retention is improved, but manufacturing cost increases
Solution Approach 1:
The patent employs standard non-volatile memory cells (such as OTPROM or EEPROM) that are inexpensive to manufacture and integrate into semiconductor devices. These memory cells use well-established fabrication processes that add minimal cost to the overall manufacturing. The calibration codes stored in these memory cells retain calibration data permanently without requiring expensive specialized non-volatile memory technologies, achieving both data retention and cost-effectiveness.
Data Source
AI summary
A semiconductor device includes a voltage generator generating a reference voltage, a first reference current generator receiving the reference voltage and generating a reference current, a non-volatile memory storing a calibration code, a first bias current generator mirroring the reference current to generate a first bias current, and a second bias current generator adjusting the reference current according to the calibration code of the non-volatile memory to generate a second bias current.