Programmable Voltage Level Shifter for SOA-Safe Bias Tracking
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Solution Overview
Problem
Existing voltage level shifter designs in integrated circuits face challenges in operating within the safe operating area (SOA) of transistors, particularly when using low voltage transistors, which can lead to increased circuit complexity, power consumption, and area.
Innovation Solution
A voltage level shifter structure with a programmable high positive supply voltage, incorporating multiple transistors and variable voltage generators that adjust the low supply voltage and gate bias voltage based on the high supply voltage, ensuring operation within the SOA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If low voltage transistors are used to reduce power consumption, then power consumption is reduced, but the transistors operate outside the safe operating area (SOA)
Solution Approach 1:
The patent implements dynamic voltage adjustment by introducing a programmable high supply voltage (VH) that can be adjusted in real-time. The low supply voltage (VL) and gate bias voltage (VGB) are dynamically adapted based on the VH level, allowing the transistors to operate within their SOA while maintaining low power consumption characteristics. This dynamic adaptation resolves the contradiction by enabling the system to switch between power-efficient operation and safe operation modes as needed.
Solution Approach 2:
The patent changes the voltage parameters (VL, VGB, VH) to resolve the contradiction. By programmably adjusting VH and相应地 adjusting VL and VGB, the system can operate low voltage transistors within their SOA. The parameter changes enable the transistors to maintain their low power consumption advantage while operating safely within specified voltage limits.
2Reliability
If asymmetric high voltage transistors (LDMOSFETs) are used to avoid operation outside SOA, then safe operating area operation is ensured, but circuit complexity increases
Solution Approach 1:
Instead of changing the transistor structure to asymmetric LDMOSFETs, the patent changes the operating parameters (VL, VGB, VH) to keep symmetric low voltage transistors within their SOA. This parameter-based solution avoids the complexity of asymmetric transistor design while achieving the same reliability goal.
Solution Approach 2:
The patent uses symmetric low voltage transistors that are already proven to be reliable when operated within their SOA, rather than introducing new asymmetric LDMOSFET structures. The solution copies the successful symmetric design approach and combines it with programmable voltage control to achieve both simplicity and reliability.
3Reliability
If discrete biasing circuits are used to avoid operation outside SOA, then safe operating area operation is ensured, but power consumption and area increase
Solution Approach 1:
The patent merges the voltage generation functions into an integrated system where the programmable VH generator and the VL/VGB generators work together. This unified approach eliminates the need for separate discrete biasing circuits, reducing both power consumption and area while maintaining SOA compliance through coordinated voltage control.
Solution Approach 2:
The voltage generation system serves multiple functions: it provides programmable VH for SOA compliance, generates VL for low voltage operation, and produces VGB for gate biasing. This multi-functional integration replaces multiple separate biasing circuits, reducing overall power consumption and area while ensuring reliable operation.
4Reliability
If asymmetric high voltage transistors (LDMOSFETs) are used to avoid operation outside SOA, then safe operating area operation is ensured, but area increases
Solution Approach 1:
The patent uses parameter changes (programmable VH with corresponding VL and VGB adjustment) to enable symmetric low voltage transistors to operate within their SOA, eliminating the need for larger asymmetric LDMOSFET structures. This approach maintains compact area while ensuring reliable operation.
Solution Approach 2:
The patent employs standard symmetric low voltage transistor designs that have compact footprints, rather than using larger asymmetric LDMOSFET structures. By combining these compact symmetric transistors with programmable voltage control, the system achieves both small area and reliable SOA-compliant operation.
Data Source
AI summary
A structure includes a level shifter, first and second variable voltage generators, and a programmable voltage generator. The level shifter includes low and high supply voltage nodes and two parallel branches, including multiple transistors, connected between the nodes. The programmable voltage generator generates and applies a high supply voltage (VH) to the high supply voltage node. VH is programmable to one of multiple possible VH levels. Based on the voltage level of VH, the first variable voltage generator generates and applies a low supply voltage (VL) to the low supply voltage node and the second variable voltage generator generates and applies a gate bias voltage (VGB) to gates of some transistors. By tracking VH and adjusting VL and VGB based on thereon, the voltage level shifter operates within the SOA at high VHs, remains operable at low VHs, and maintains operating speed at mid-level VHs.