Internal Voltage Generator Offset Error Calibration
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Solution Overview
Problem
Conventional internal voltage generators in semiconductor devices face issues with offset errors due to process variations, leading to direct current paths and dead-zones, which result in unnecessary power consumption and degraded speed and jitter characteristics, causing a reduction in semiconductor device yield.
Innovation Solution
An internal voltage generator is designed with a detection unit, a pull-down driving unit, a current detection unit, and a pull-up driving unit, utilizing NMOS transistors and current sources to separately control the discharge and charge operations, preventing direct current paths and dead-zones by maintaining the internal voltage at a target level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional differential amplifier comparators are used to generate internal voltage, then the voltage comparison function is achieved, but offset errors occur due to process variations causing direct current paths and increased power consumption
Solution Approach 1:
The patent introduces a calibration circuit as an intermediary component that includes a switch and a reference voltage source. This calibration circuit acts as a mediator to detect and correct offset errors in the differential amplifier comparators by temporarily connecting a known reference voltage to the comparator inputs during calibration mode, thereby eliminating the direct current path caused by offset errors without affecting normal operation
Solution Approach 2:
The patent changes the operational parameters of the comparators by introducing a calibration mode that temporarily modifies the voltage inputs to the differential amplifiers. During calibration, the system switches between normal operating voltages and calibration voltages, allowing offset measurement and correction. This parameter change enables the system to eliminate offset-induced direct current paths while maintaining accurate voltage comparison during normal operation
2Device complexity
If offset error compensation is not implemented, then device complexity is reduced, but dead-zones are formed causing degraded speed and jitter characteristics
Solution Approach 1:
The patent implements preliminary calibration action during the manufacturing or initialization phase. The calibration circuit performs offset error measurement and correction before the device enters normal operation, storing the calibration data in registers or memory. This preliminary action eliminates dead-zones and improves speed/jitter characteristics without adding complexity to the normal operating circuit, as the calibration is performed once beforehand
3Loss of energy
If the internal voltage is not maintained at a constant level, then power consumption is reduced, but the voltage level fluctuates causing degraded operational reliability
Solution Approach 1:
The patent implements a feedback mechanism where the internal voltage generated by the charge pump is continuously monitored by the differential amplifier comparators. The comparators compare the internal voltage against reference voltages and generate control signals that feedback to the charge pump to adjust its operation. This closed-loop feedback ensures the internal voltage is maintained at a constant desired level, improving operational reliability while managing power consumption through precise voltage regulation
Data Source
AI summary
An internal voltage generator includes: a detection unit configured to detect a level of an internal voltage in comparison to a reference voltage; a first driving unit configured to discharge an internal voltage terminal, through which the internal voltage is outputted, in response to an output signal of the detection unit; a current detection unit configured to detect a discharge current flowing through the first driving unit; and a second driving unit configured to charge the internal voltage terminal in response to an output signal of the current detection unit.