MEMS Probe Attenuator Switching for Low-Parasitic Bandwidth
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Solution Overview
Problem
Existing test equipment relies on mechanical switches and electromechanical relays for attenuating signals, which introduce parasitic capacitance, bulk, slow switching speeds, and high power consumption, leading to signal distortion and inaccurate measurements.
Innovation Solution
Integration of micromachined switches and attenuators, such as resistors, in a common substrate or probe housing, reducing parasitic capacitance and increasing bandwidth by enabling precise signal attenuation without mechanical switches or electromechanical relays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical switches or electromechanical relays are used to switch attenuators into or out of signal paths, then signal attenuation can be achieved, but parasitic capacitance is introduced into the signal path which distorts the signal and limits bandwidth
Solution Approach 1:
The patent replaces mechanical switches and electromechanical relays with solid-state electronic switching components. This substitution eliminates the mechanical moving parts that generate parasitic capacitance, thereby removing the source of signal distortion while maintaining the signal attenuation function through electronic means.
Solution Approach 2:
The patent changes the electrical parameters of the switching system by transitioning from high-capacitance mechanical contacts to low-capacitance solid-state switches. This parameter change directly reduces parasitic capacitance values, improving signal fidelity and extending bandwidth without sacrificing attenuation capability.
2Ease of operation
If electromechanical relays are used for switching attenuators, then signal paths can be switched, but the relays draw significant power and operate slowly
Solution Approach 1:
The patent replaces electromechanical relays with solid-state electronic switches that require minimal power to operate. These solid-state components use electronic field effects rather than electromagnetic coils to control switching, dramatically reducing power consumption while maintaining full switching capability for attenuator selection.
Solution Approach 2:
The patent implements rapid switching capability through solid-state components that can change states almost instantaneously compared to the mechanical movement required by relays. This enables periodic or dynamic switching of attenuators at high speeds, allowing the system to adapt quickly to changing signal conditions without power-intensive mechanical motion.
3Ease of manufacture
If mechanical switches are used to switch attenuators, then attenuation can be implemented, but the switches are large in size introducing bulk to the device
Solution Approach 1:
The patent replaces bulky mechanical switch assemblies with compact solid-state electronic switching components. These solid-state devices can be integrated into circuit boards or even monolithically integrated with the attenuator elements, dramatically reducing the physical volume required for the switching mechanism while maintaining full functionality.
Solution Approach 2:
The patent merges the switching components and attenuator elements into a more integrated assembly. By combining previously separate mechanical switch and attenuator components into a unified solid-state structure, the overall device bulk is reduced while maintaining the ability to switch between different attenuation levels.
4Ease of operation
If mechanical switches are used for switching attenuators, then signal paths can be switched, but the switching speed is limited
Solution Approach 1:
The patent replaces mechanical switches with solid-state electronic switches that eliminate the need for physical contact movement. This substitution enables switching speeds limited only by electronic response times rather than mechanical inertia, allowing rapid switching of attenuators to track fast-changing signal conditions.
Solution Approach 2:
The patent implements dynamic switching capability through solid-state components that can change their electrical characteristics almost instantaneously. This dynamic response allows the attenuator switching to keep pace with rapidly varying input signals, something that mechanical switches cannot achieve due to their inherent mechanical response time limitations.
Data Source
AI summary
One or more micromachined (MEMS) switches switch attenuators, such as resistors, into or out of a signal path, such as of a test instrument. The MEMS switches can be fabricated on the same substrate as the attenuators, or the switches or attenuators can be mounted on the same substrate as the others are fabricated. An instrument probe includes attenuators and MEMS switches that are controlled by the instrument and/or by a control circuit in the probe. Optionally, the probe includes reactive elements, such as capacitors, and MEMS switches to compensate for electrical characteristics of the probe and/or probe lead, and the probe or a test instrument automatically sets the MEMS switches to connect appropriate ones of the reactive elements to a signal path within the probe.