High-Voltage Differential Pair in Low-Voltage CMOS Processes
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Solution Overview
Problem
Advanced integrated circuit fabrication processes that operate at low voltages face challenges in interfacing with higher voltage circuits, particularly in applications like implantable medical devices for functional electrical stimulation, where processing high voltage signals is essential but difficult due to transistor breakdown voltages.
Innovation Solution
A high voltage differential pair and op amp are implemented in a low voltage semiconductor process using high voltage current sources, current sinks, and stacks of transistors to expand the operating voltage range, allowing for safe processing of high voltage signals without exceeding transistor breakdown voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low voltage CMOS fabrication process is used, then power consumption is reduced and logic density is increased, but the ability to process high voltage signals is lost due to transistor breakdown voltage limitations
Solution Approach 1:
The patent divides the voltage handling function into multiple segments: low voltage CMOS transistors handle signal processing while high voltage current sources and sinks handle voltage level adaptation. This segmentation allows each component to operate within its optimal voltage range, preventing breakdown while maintaining high voltage signal processing capability.
Solution Approach 2:
The patent introduces high voltage current sources and sinks as intermediary components between the low voltage CMOS circuit and high voltage signals. These intermediaries translate high voltage signals into forms that can be processed by low voltage transistors, enabling interface between different voltage domains without exposing the CMOS transistors to breakdown conditions.
2Adaptability or versatility
If special mixed voltage processes are used, then high voltage and low voltage devices can coexist, but performance capabilities are limited and manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by using high voltage components only where needed for voltage interface functions, while the majority of the circuit operates with standard low voltage CMOS. This localized approach to voltage handling reduces overall process complexity compared to fully mixed voltage processes, as only specific blocks require special high voltage transistors.
3Manufacturing precision
If standard low voltage transistors are used, then manufacturing precision is high and power consumption is low, but the maximum operating voltage is limited by breakdown voltage
Solution Approach 1:
The patent transitions from a single voltage dimension to multiple voltage dimensions by introducing high voltage current sources and sinks that operate at different voltage levels than the low voltage CMOS transistors. This dimensional separation allows the circuit to handle high voltage signals while the transistors themselves continue to operate at their optimized low voltage levels, maintaining both manufacturing precision and voltage tolerance.
Data Source
AI summary
A high voltage differential pair and op amp implemented in a low voltage semiconductor process. The high voltage differential pair expands the incoming common mode voltage of a differential pair to multiple times the normal operating voltage of the differential pair through the use of high voltage current sources, current sinks and stacks of transistors. The high voltage op amp includes a high voltage input stage and a high voltage common source amplifier to expand the output voltage range to multiple times the normal operating voltage of the op amp.