NI PXI-5691 Block Diagram

The following figure is a block diagram of the NI PXI-5691 RF amplifier. The text that follows the figure describes the basic elements of the diagram.

Caution  The NI 5691 RF amplifier input connectors are sensitive to ESD. Observe all precautions described in ESD Information when making, removing, or adjusting connections to the NI RF amplifier input connectors. For example, do not adjust an antenna connected to the NI RF amplifier input without observing all ESD precautions.

Channel 0

Channel 0 (CH 0) functions as a fixed gain amplifier. This channel offers low noise figure and a flat frequency response. Use CH 0 as you would a conventional fixed gain amplifier.

Channel 1

Channel 1 (CH 1) functions as a programmable amplifier containing two user-selectable paths.

Main path—Consists of fixed gain amplification with a step attenuator that is adjustable by software in 0.5 dB nominal steps according to user-specified gain settings.

Direct path—Provides the option of bypassing the attenuator-amplifier circuitry. This path is useful for handling higher power inputs that may cause distortion in the NI RF amplifier.

By default, CH 1 is initialized to use the main path with minimum gain. Refer to Using CH 1 for more information about using the CH 1 main and direct paths.

Caution  Observe maximum input power ratings to avoid damaging the NI RF amplifier.

Refer to the NI PXI-5691 Specifications document, available in PDF format at Start»All Programs»National Instruments»NI-5690»Documentation, for detailed specifications of both channels, including available gain ranges, gain variation by temperature, and power ratings.