Supply Unit for Charged Particle Beam Column
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Solution Overview
Problem
The inefficiency in driving a deflecting electrode of a charged particle beam column due to parasitic capacitance in coaxial cables, which requires costly scanning voltage supplies and limits maximal scanning speed.
Innovation Solution
A supply unit that includes a first amplifier, a first resistor, a second amplifier, and a coaxial cable, where the same driving signals are supplied to the signal line and the main shield of the coaxial cable, effectively eliminating the capacitance of the coaxial cable, and optionally using a double shielded coaxial cable with an additional shield and an auxiliary coaxial cable to compensate for signal delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coaxial cables are used to transmit scanning voltages to the deflecting electrode, then the electrode can be driven reliably in the noisy environment, but the parasitic capacitance of the cable reduces scanning speed and increases power requirements
Solution Approach 1:
The patent applies the 'Blessing in disguise' principle by converting the harmful parasitic capacitance of the coaxial cable into a beneficial element. A second amplifier is connected to the cable shield and provides a signal that is 180 degrees out of phase with the signal on the center conductor. This creates an opposing electric field that cancels the capacitive coupling effect, effectively neutralizing the parasitic capacitance and enabling high-speed scanning despite the presence of the long cable.
2Reliability
If coaxial cables are used to transmit scanning voltages, then signal transmission is achieved, but costly high-power scanning voltage supplies are required
Solution Approach 1:
The patent applies the 'Blessing in disguise' principle by converting the harmful parasitic capacitance of the coaxial cable into a beneficial element. A second amplifier is connected to the cable shield and provides a signal that is 180 degrees out of phase with the signal on the center conductor. This creates an opposing electric field that cancels the capacitive coupling effect, effectively neutralizing the parasitic capacitance and enabling high-speed scanning despite the presence of the long cable.
Solution Approach 2:
The patent applies the 'Segmentation' principle by dividing the single amplification function into two separate amplifiers. The first amplifier drives the center conductor with the scanning signal, while the second amplifier drives the cable shield with an inverted signal. This segmentation allows each amplifier to operate at lower power levels while achieving the net effect of driving the electrode, thereby reducing total power consumption and avoiding the need for a single high-power amplifier.
3Speed
If the capacitance of the coaxial cable is eliminated by differential driving, then scanning speed increases, but device complexity increases due to additional amplifiers and shielding
Solution Approach 1:
The patent applies the 'Universality' principle by making the coaxial cable serve multiple functions simultaneously. The cable not only transmits the scanning voltage signal on its center conductor but also acts as part of the driving mechanism through its shield, which is actively driven by the second amplifier. This multi-functionality allows the cable structure to contribute to both signal transmission and parasitic capacitance cancellation, reducing the need for separate compensation circuits and minimizing overall system complexity.
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 approach enhances the efficiency of driving the electrode, reducing the need for costly scanning voltage supplies and increasing the maximal scanning speed by virtually eliminating parasitic capacitance and minimizing signal delays.
Implementation Method 1
supplying to (a) a signal line of the coaxial cable and (b) a main shield of the coaxial cable substantially the same driving signals thereby virtually eliminating the capacitance of the coaxial cable
Data Source
AI summary
A supply unit for driving an electrode of a charged particle beam column, the supply unit includes a first amplifier and a second amplifier that are configured to receive an input signal, an output of the first amplifier is coupled, via the first resistor, to a signal line of the coaxial cable, an output of the second amplifier is coupled, via the second resistor, to a main shield of the coaxial cable, one port of the first amplifier and one port of the second amplifier are coupled to a power supply return port. The signal line is configured to provide a first driving signal to an that is coupled between the signal line and the power supply return port.