3Distribution Amplifiers
Distribution amplifier options
10 MHz and 5 MHz distribution amplifiers.
It is common to distribute a 10 MHz or 5 MHz frequency reference (from a rubidium or
cesium oscillator, for example) throughout a facility. This frequency reference is used as the
timebase for instruments in test & measurement, broadcast, telecommunication or basic
research applications.
A distribution amplifier used in this application should provide sine wave outputs, amplitude
leveling, low additive phase noise, low spur levels, narrow bandwidth, high channel-to-
channel isolation, small phase variation with temperature, and high return loss on all 50
inputs and outputs.
CMOS Logic distribution amplifier.
A CMOS Logic distribution amplifier has one logic-level input and several outputs. A typical
application is the distribution of a 1 pulse-per-second timing mark from a GPS receiver or an
8kHz frame clock for telecommunications.
There are no established standards for sending 5 V logic pulses over 50coax. Standard
logic ICs are not designed to drive 50 loads. To avoid problems, a logic distribution
amplifier should have the following characteristics: high input impedance with hysteresis,
high current outputs with 50 source impedance, fast transition times, small overshoot,
small ground bounce, small insertion delay and low channel-to-channel timing skew.
Broadband 50 and 75 distribution amplifiers.
Broadband distribution amplifiers have one analog input and several analog outputs. A wide
bandwidth allows these distribution amplifiers to be used in many applications including the
distribution of frequency references, IRIG timing signals, composite video, audio, etc.
Typically test & measurement and research applications will use 50 inputs and outputs
while video and broadcast applications will use the 75 version.
Important characteristics of broadband amplifiers include input protection, wide bandwidth
(including dc), flat frequency response, large dynamic range, low offset voltage, low noise,
high slew rate, and low distortion. Outputs should have high current compliance and accurate
50 or 75 output impedance for high return loss. Composite video applications require
low differential gain and low differential phase errors to prevent color shifts or color
saturation changes verses luminance levels.
Stanford Research Systems
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