87104/6D Multiport Electromechanical Coaxial Switches

Introduction

Modern automated test systems demand higher accuracy and performance than ever before. The Keysight Technologies, Inc. 87104/6D electromechanical (EM) multiport switches offer improvements in insertion loss repeatability and isolation necessary to achieve higher test system performance. Long life, repeatability, and reliability lower the cost of ownership by reducing calibration cycles and increasing test system uptime, and are vital to automated test system (ATE) measurement integrity over time.

High performance multiport switches for microwave and RF instrumentation and systems

• 0.03 dB repeatability ensures accuracy and reduces calibration cycles for the entire 5 million cycle operating life
• Excellent isolation, typically > 65 dB at 40 GHz maximizes measurement accuracy and improves system dynamic range
• Magnetic latching with SP4T and SP6T configurations

Description

The Keysight 87104/6D SP4T EM multiport switches provide the life and reliability required for automated test and measurement, signal monitoring, and routing applications. Innovative design and careful process control create switches that meet the requirements for highly repeatable switching elements in test instruments and switching interfaces. The switches are designed to operate for more than 10,000,000 cycles. The exceptional 0.03 dB insertion loss repeatability is warranted for 5 million cycles at 25 °C. This reduces sources of random errors in the measurement path and improves measurement uncer­tainty. Switch life is a critical consideration in production test systems, satellite and antenna monitoring systems, and test instrumentation. The longevity of these switches increases system uptime, and lowers the cost of ownership by reducing calibration cycles and switch maintenance.

Operating to 40 GHz these switches exhibit exceptional isolation performance required to maintain measurement integrity. Isolation between ports is typically > 65 dB to 40 GHz. This reduces the influence of signals from other channels, sustains the integrity of the measured signal, and reduces system measurement uncertainties. These switches also minimize measurement uncertainty with low insertion loss and reflection, which make them ideal elements in large multi-tiered switching systems.

Both 87104/6D are designed to fall within most popular industry footprints. The 2¼ inch square flange provides mounting holes, while the rest of the 2½ inch long by 2¼ inch diameter body fits easily into most systems. Ribbon cable or optional solder terminal connections accommodate the need for secure and efficient control cable attachment.

Option 100 provides solder terminal connections in place of the 16-pin ribbon drive cable. Option 100 does not incorporate the “open all paths” feature.

Opto-electronic interrupts improve reliability and extend the life of the switch by eliminating DC circuit contact failures characteristic of conventional electromechanical switches. The 87104/6D switches have an interrupt circuit that provides logic to open all but the selected ports, and then close the selected paths. All other paths are terminated with 50 ohm loads, and the current to all the solenoids is then cut off. These versions also offer independent indicators that are controlled by optical interrupts in the switch. The indicators provide a closed path between the indicator common pin and the corresponding sense pin of the selected path.

Applications

Multiport switches find use in a large number of applications, increasing system flexibility and simplifying system design.

Simple signal routing

The simplest signal routing scheme takes the form of single input to multiple outputs. These matrixes are often used on the front of an analyzer in order to test several two-port devices sequentially or for testing multiport devices. In surveillance applications, a multiport switch can be used for selecting the optimum antenna in order to intercept a signal. Two methods can be used to accomplish the single input to multiple output arrangement. Traditionally where isolation greater than 60 dB was required, a tree matrix composed of SPDT switches was used. While this gave great isolation, it was at the cost of more switches (Figure 3). The 87104/6D switches have port-to-port isolations typically greater than 65 dB at 40 GHz, eliminating the need to use a tree matrix in order to achieve high isolation (Figure 4). In addition to the reduced part count, the path lengths are shorter, so insertion loss is less, and paths are of equal length, so phase shift is constant.

Full access switching

Full access switching systems give the flexibility to route multiple input signals to multiple outputs simultaneously. Full access switching matrixes find use in generic test systems; they provide flexible routing of signals to and from many different devices under test and stimulus and analysis instrumentation. Cross-point matrixes, using single-pole double-throw (SPDT) and cross-point switches, have traditionally been used in order to maintain high channel-to-channel isolation (Figure 5). As with the tree matrixes, it is at the cost of more hardware and performance. Full access switching can also be achieved using multiport switches (Figure 6).

The advantage of the multiport matrix over the cross-point matrix is lower insertion loss and improved SWR performance due to consistent path length and fewer switches and connecting cables.

Dedicated switching

There are a number of applications where switching is used, not for flexibility, but to accomplish a particular function within an instrument. For example, switched filter banks for reducing harmonics in the output of sources or to the input of analyzers can use multiport switches in series to select the right filter for the band of interest. For larger switching systems, where many switches will be used to provide complex signal routing, a switch driver such as the Keysight 11713B/C with 87104/6 switches is recommended.

Driving the switch

Each RF path can be closed by applying ground (TTL “High” for Option T24) to the corresponding “drive” pin. In general, all other RF paths are simultaneously opened by internal logic.