Charge Pump Segmentation for Low Voltage Area Reduction
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Solution Overview
Problem
The integration of Flash memory cells in 90 nm CMOS technologies faces challenges due to the need for low voltage transistors to operate with decreasing supply voltages, leading to difficulties in designing charge pump systems that require high operating voltages while minimizing area occupation and current consumption, especially in applications with wide external supply voltage ranges.
Innovation Solution
A charge pump system where only the first pump is supplied by an internal limited voltage, with the second and third pumps receiving this voltage to generate the necessary working voltages, utilizing LV transistors for the first pump and HV transistors for the others, and controlling their operation to minimize overlapping consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If many charge pump stages are used to meet the lower limit of external supply voltage range, then the charge pump system can operate at low supply voltages, but the silicon area occupied by the system increases
Solution Approach 1:
The charge pump system is divided into multiple independent pumps (first pump, second pump, third pump), each capable of generating specific voltage levels. This segmentation allows selective activation of pumps based on operating conditions, reducing the need for all pumps to be simultaneously active and thus reducing area requirements compared to a single large charge pump system.
Solution Approach 2:
The system dynamically selects which pumps to activate based on the external supply voltage range and operational requirements. The control logic enables adaptive operation where not all pumps run continuously, allowing the system to meet low voltage requirements when needed while minimizing area occupation during normal operation.
2Reliability
If pump capacitors of great capacitance are used, then the charge pump system can meet the lower limit of external supply voltage range, but the silicon area occupied by the system increases
Solution Approach 1:
The capacitance requirement is distributed across multiple pumps rather than requiring a single large capacitor. Each pump uses smaller capacitors suited to its specific function, reducing total area while maintaining voltage generation stability through coordinated operation of multiple pumping units.
3Adaptability or versatility
If the second and third pumps are simultaneously activated, then both working voltages are generated, but current consumption increases
Solution Approach 1:
The control logic implements periodic or conditional activation of the second and third pumps based on operational requirements. Instead of continuous simultaneous operation, pumps are activated only when their specific voltage generation is needed, reducing overall current consumption while maintaining the capability to generate both working voltages when required.
4Adaptability or versatility
If high voltage transistors are used throughout the charge pump system, then the system can operate across the full external supply voltage range, but the silicon area occupied by the system increases
Solution Approach 1:
Different transistor types are used in different parts of the system based on local requirements. The first pump uses low voltage transistors optimized for low voltage operation, while the second and third pumps use high voltage transistors only where high voltage generation is required. This localized optimization reduces overall silicon area while maintaining full supply voltage range adaptability.
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
This configuration reduces silicon area occupation and current consumption, allowing efficient generation of required voltages for reading, programming, and erasing operations while maintaining controlled pump current usage, particularly beneficial in low internal supply voltage scenarios.
Implementation Method 1
a charge pump system for the generation, starting from a single external supply voltage reference, of the internal voltage references that are necessary for the correct operation
Data Source
AI summary
A charge pump system is provided that includes at least one first pump for generating a first working voltage, a second pump for generating a second working voltage, and a third pump for generating a third working voltage. The first pump is connected to an internal supply voltage reference that can having a limited value, and has an output terminal connected to the second and third pumps so as to supplying them with the first working voltage as their supply voltage. A method is also provided for managing the generation of voltages to be used with such a charge pump system.