Programmable Termination Circuit ESD Protection
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Solution Overview
Problem
Programmable ICs face challenges in providing effective electrostatic discharge (ESD) protection and impedance matching for various interface standards, leading to potential damage from ESD and signal reflections due to high parasitic capacitance and silicon area consumption, especially in high-I/O devices like FPGAs.
Innovation Solution
A programmable termination circuit with active FET-based sub-circuits that can be selectively enabled to match impedance and provide ESD protection using body diodes, reducing parasitic capacitance and silicon area, while adjusting common mode offsets to match difference amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ESD protection circuits are used, then ESD protection is provided, but silicon area is considerably consumed
Solution Approach 1:
The patent combines ESD protection functionality with termination circuit functionality into a single integrated circuit. The termination circuit includes pull-up and pull-down circuits that also serve as ESD protection paths, eliminating the need for separate ESD protection circuits and reducing silicon area consumption.
Solution Approach 2:
The termination circuit is designed to perform multiple functions: impedance matching for signal termination and ESD protection. The same transistors and circuit paths used for termination also provide ESD protection, making the circuit universal and reducing overall component count.
2Reliability
If termination circuits are added to match impedance, then signal reflections are minimized, but parasitic capacitance increases
Solution Approach 1:
The termination circuit uses controllable transistors that can be dynamically enabled or disabled based on operational mode. During high-speed operation, the termination can be adjusted or disabled to minimize parasitic capacitance effects, while still providing impedance matching when needed.
Solution Approach 2:
The circuit allows dynamic adjustment of termination impedance parameters to optimize performance for different operating conditions. By changing the termination state (enabled/disabled or different impedance levels), the circuit minimizes parasitic capacitance impact during critical high-speed operations.
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
The solution effectively reduces parasitic capacitance, minimizes silicon area, and provides robust ESD protection, enabling high-speed linear equalization and flexible impedance matching for various applications.
Implementation Method 1
circuits to protect the system from electro-static discharge ("ESD"). ESD transfers a sudden and momentary electric current to a circuit from an external source.
Implementation Method 2
The transistors are arranged to form series-coupled source/drain junction diodes that provide ESD protection by clamping voltage
Implementation Method 3
termination circuits are generally included in a transmitter and/or receiver analog front-end circuits to match impedance of the circuits and transmission medium and minimize signal reflections
Implementation Method 4
differences of impedance between a transmission line and a receiver front-end circuit can adversely cause a portion of a transmitted signal to be reflected
Data Source
AI summary
A termination circuit configured to provide electrostatic discharge (ESD) protection is provided. Termination sub-circuits are coupled in parallel, each including respective pull-up and pull-down circuits. Each pull-up circuit has two transistors of a first type coupled in series between a data input and Vdd, a gate of one of the two transistors being coupled to a control input and a gate of the other one of the two transistors being coupled to a first enable input of the termination sub-circuit. Each pull-down circuit has two transistors of a second type coupled in series between the data input and Vss or ground, a gate of one of the two transistors being coupled to the control input and the gate of the other one of the two transistors being coupled to a second enable input of the termination sub-circuit.