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At the heart of this digital attenuation solution is a series of USB/TTL controlled MMIC digital attenuators and Ethernet controlled rack mountable subsystems that is suitable for a multitude of RF and microwave applications up to 6 GHz. Designed with budget and performance concerns in mind, these devices offer superior RF characteristics and performance suitable for automated bench testing in wireless backhaul, fading simulation and other high performance wireless applications. All of these models are RoHS compliant.

The USB/TTL controlled MMIC digital attenuators, Model 4205 Series, are available in three attenuation configurations up to 95.5 dB in 0.5 dB steps and operate over the 0.2 to 6 GHz frequency range. These devices are supplied with both parallel-TTL and USB 2.0 interfaces. The mode of operation is determined by the source of DC power to the unit. Note: The two interfaces cannot be used in a simultaneous use configuration.

Figure 1

Figure 1 Attenuation versus frequency plot.

Table 1

TTL Control: Two pins are specified for supply voltage and ground. The remaining pins will accept TTL control signals to activate or de-activate a particular attenuation cell. A TTL high will energize a cell to the high attenuation state, whereas a TTL low will maintain a cell in its zero attenuation state. The TTL control connector is an AMP-Latch 10-pin ribbon cable connector that mates with AMP P/N 746285-1, which is supplied with each device.

Table 2

USB Control: The USB interface is compatible with standard USB 2.0 interfaces. In USB mode, DC power to the attenuator is provided by the host USB connection. The attenuator operates as a USB CDC device and accepts simple ASCII text commands. This allows the unit to be controlled from any system capable of sending data via a standard COM port-style interface. The USB port is a 5-pin female series B mini socket and mates with most standard USB 5-pin male series B mini plug connectors.

These devices offer uninterrupted RF when changing attenuation dB values with excellent solid-state repeatability and performance. Available in three ranges of 0 to 31.5 dB, 63.5 dB and 95.5 dB configurations (see Figure 1). Tables 1 through 4 show the performance specifications.

Control software is also included with each device. Aeroflex / Weinschel’s LabVIEW based USB Control Center Software (AUCS) can also be used in the operation of this series of digital attenuators. The AUCS will allow the user to set up, control and perform test and measurements using these digital attenuators over a standard USB 2.0 communication interface.

Table 3

The low profile design of the Model 4205 Series and convenient 12 mounting holes on the front, sides, top and bottom allow for mounting in any subsystem or rack configuration. With this in mind, Aeroflex / Weinschel offers a standard line of half-rack (Model 8320) and full 19 inch rack turn-key solutions (Model 8321 and 8331) containing these devices that offer USB, Ethernet control or front panel operation. Attenuation matrices and custom configurations can also be designed using these building block components. These units are also supplied with LabVIEW-based control software. These devices are already employed in specific applications that include simulation of the cell phone-to-base station RF link; simulation of the WiFi client-to-access point RF link; precise power level control of RF and microwave signal generators.

Table 4

Aeroflex / Weinschel,
Frederick, MD
(301) 846-9222,