Programmable Voltage Level Shifter for SOA-Safe Low Supply Tracking
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Solution Overview
Problem
Existing voltage level shifters in integrated circuits face challenges in balancing performance, size scaling, and power consumption, with low voltage transistors often operating outside the safe operating area (SOA), and modifications to avoid this issue increase circuit complexity and power consumption.
Innovation Solution
A voltage level shifter with a programmable high supply voltage and a variable low supply voltage, generated by a programmable and variable voltage generator, respectively, ensures operation within the SOA by adjusting the low supply voltage based on the high supply voltage, using symmetric transistors to maintain efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low voltage transistors are used in voltage level shifters, then power consumption is reduced, but the transistors quickly operate outside the safe operating area (SOA)
Solution Approach 1:
The patent implements dynamic voltage adjustment by making the low supply voltage (VDDW) variable rather than fixed. The voltage level shifter dynamically adjusts VDDW based on operating conditions to maintain transistor operation within the safe operating area while optimizing power consumption. This is achieved through control circuitry that monitors and adjusts the voltage levels in real-time.
Solution Approach 2:
The patent changes the voltage parameter by implementing a programmable high supply voltage (VH) and a variable low supply voltage (VDDW). By programmably setting VH and dynamically adjusting VDDW, the system can adapt voltage parameters to keep transistors within SOA while maintaining low power consumption characteristics.
2Reliability
If asymmetric high voltage transistors (LDMOSFETs) are used to avoid operation outside SOA, then reliability is improved, but circuit complexity increases
Solution Approach 1:
The patent applies asymmetry by using asymmetric high voltage transistors (LDMOSFETs) in specific positions within the voltage level shifter circuit. These asymmetric transistors are strategically placed to handle high voltage operations while maintaining overall circuit functionality, thereby ensuring reliable operation within SOA for high voltage paths.
Solution Approach 2:
The patent implements multi-functionality by designing the voltage level shifter to operate across multiple voltage domains (different VH and VDDW combinations) using a unified circuit architecture. The same circuit structure can adapt to different voltage requirements through programmable VH and variable VDDW, eliminating the need for separate dedicated circuits for each voltage level.
3Reliability
If discrete biasing circuits are added to avoid operation outside SOA, then reliability is improved, but power consumption and area increase
Solution Approach 1:
The patent merges the biasing functionality into the main voltage level shifter circuit rather than using separate discrete biasing circuits. The biasing is integrated through the programmable VH and variable VDDW control mechanisms, which simultaneously perform voltage level shifting and biasing functions, thereby avoiding additional power-consuming discrete circuits.
Solution Approach 2:
The voltage level shifter implements self-service by automatically adjusting its own biasing conditions through the variable VDDW and programmable VH. The circuit monitors its operating state and self-adjusts voltage levels to maintain transistors within SOA without requiring external discrete biasing circuits, thereby reducing both power consumption and circuit area.
Data Source
AI summary
A disclosed circuit structure includes a voltage level shifter connected to a variable voltage generator for receiving a low supply voltage and to a programmable voltage generator for receiving a high supply voltage that is higher than the low supply voltage. The high supply voltage is programmable to one of multiple different voltage levels. The variable voltage generator tracks the voltage level of the high supply voltage and outputs the low supply voltage based thereon. The high supply voltage is tracked either directly or using the trim bit signal employed by the programmable voltage generator to program the high supply voltage. The low supply voltage is high when the high supply voltage is high to ensure operation within the safe operating area and is low when the high supply voltage drops below some threshold level to ensure operability and, optionally, improve operating speed.