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March 5, 2007
Introduction
System test engineers manufacturing RF and microwave components for the aerospace and defense, satellite, broadband wireless access and wireless communications industries face increasing pressure to maximize manufacturing throughput and reduce cost of test. Expanded capability of components requires numerous tests and more complex signal routing and monitoring capability.
Engineers responsible for system integration require reliable, repeatable performance in switch matrixes and automated test systems. The reliability of a test system over time is critical as any delay in throughput due to downtime or recalibration, or decrease in yield could have a tremendous impact on a company's bottom line in terms of both time and cost. To achieve system reliability today's switches must meet the most stringent requirements for highly repeatable switching throughout their operating life.
Switching Requirements are Becoming More Stringent
Today's high speed manufacturing requires high performance, repeatable switching elements in test instruments and switching interfaces and automated test systems. Additionally, they must be defined by the following characteristics:
- Operating life - is a critical consideration in production test systems, satellite and antenna monitoring systems, and test instrumentation. The operating life of electro-mechanical switches is defined as the number of cycles the switch will complete while meeting all RF and repeatability specifications. One life cycle is defined as one closing and opening of the jumper contact or one on/off triggering of the electromagnetic coils in the switch.
- Repeatability - has a direct impact on the measurement uncertainty of a test setup. For example, when a network analyzer connected to a multiport test set is used to test multiple devices, the certainty of the system takes into account the repeatability of both the network analyzer and the switch. So, if the network analyzer has 0.01 dB repeatability and a switch has 0.03 dB, the total measurement uncertainty will be 0.044 dB. However, if the switch repeatability is 0.1 dB and the PNA repeatability stays the same, the total measurement uncertainty increases to 0.142 dB. See Equations at the end of this document.
- High isolation - reduces the influence of signals from other channels, sustains the integrity of the measured signal, and reduces system measurement uncertainties.
- Flexible configurations and broadband capability - provide the flexibility to create complex matrixes and automated test systems for many different applications and frequencies. See Switching Applications at the end of this document for a brief summary of possible applications for multiport and transfer switches.
- Low cost - reduces budgetary constraints allowing manufacturers to be more competitive in today's price sensitive markets.
Agilent - The Electromechanical Switch Performance Leader
The L Series electromechanical (EM) switches provide the life and reliability required for automated test and measurement, signal monitoring, and routing applications. These high-performance EM switches can be used in a large number of applications, increasing system flexibility and simplifying system design. The longevity of these switches increases system uptime, and lowers the cost of ownership by reducing calibration cycles and switch maintenance.
Long operating life with guaranteed 0.03 dB insertion loss repeatability
Operating life is very dependant on the jumper contact mechanism, contact resistance, and the material and plating used in all the key RF components of a switch. Agilent EM coaxial switches are produced with meticulous manufacturing processes and stringent quality assurance systems. The L7104/L7204A, B, C SP4T, L7106/L7206A, B, C SP6T multiport, and L7222 transfer switches are designed to operate for more than 2,000,000 cycles.
High insertion loss repeatability reduces sources of random errors in the measurement path and improves measurement uncertainty. The L Series have a guaranteed 0.03 dB insertion loss repeatability throughout their operating life of 2 million cycles. To achieve this repeatability specification, Agilent EM switches incorporate a unique design, which includes a wiping mechanism that cleans debris off the center conductor tip every cycle, eliminating the particle build-up that is prevalent in conventional EM switch designs.
Exceptional performance reduces cost of test
Operating from DC to 26.5 GHz, these switches exhibit exceptional isolation performance required to maintain signal integrity. Isolation between ports is typically >90 dB to 12 GHz and >80 dB to 26.5 GHz, reducing the influence of signals from other channels and system measurement uncertainties. The L Series switches also minimize measurement uncertainty making them ideal for use in large multi-tiered switching systems.
As a complete selection of switch configurations up to 26.5 GHz, the Agilent L Series delivers the required functionality and flexibility to deal with the most switch complex matrix and automatic test equipment (ATE) applications. The L7222C transfer switches provide flexible switching to help simplify the design of signal routing and conditioning applications.
Agilent's L Series switches offer excellent performance at an affordable price, minimizing the pressure associated with stringent budgetary constraints. The L Series gives customers the flexibility to choose between life expectancy and cost, without sacrificing switch performance.
Equations
Since uncertainty errors are random and not systematic, root sum square (RSS) is used calculate the total measurement uncertainty.
Scenario 1
PNA repeatability = 0.01dB, EM switch repeatability = 0.03dB
Total measurement uncertainty = = 0.044dB
Scenario 2
PNA repeatability = 0.01dB, EM switch repeatability = 0.1dB
Total measurement uncertainty =  = 0.142dB
Switching Applications
Multiport switch applications
Typical switching applications for multiport coaxial switches include: signal routing, a single input to multiple outputs; full access or matrix switching, multiple input signals to multiple outputs simultaneously; transfer switching, using a switch to insert or remove a device in a signal path and selection of multiple input signals to one measurement instrument.
Transfer switch applications
Transfer switches can be used in many different applications to increase system flexibility and simplify system design. The following are five examples: switch between two inputs and two outputs, use as a drop-out switch, use for signal reversal, configure as a SPDT switch, and bypass an active device.
About Agilent
Agilent Technologies Inc. (NYSE: A) is the world's premier measurement company and a technology leader in communications, electronics, life sciences and chemical analysis. The company's 19,000 employees serve customers in more than 110 countries. Agilent had net revenue of $5.0 billion in fiscal 2006. Information about Agilent is available on the Web at www.Agilent.com.
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Contacts:
Janet Smith
Agilent Technologies
+1 970 679 5397
janet_smith@agilent.com
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