BROADBAND AMPLIFIERS--MT1550 UPSTREAM AMPLIFIER

The MT1550 is a low-cost
programmable-gain power amplifier
IC for use in CATV upstream
applications. The Microtune?
MT1550 is a 3.3 volt part optimized
for the DOCSIS? 1.0, 1.1, 2.0 and
Euro-DOCSIS upstream standard.
An on-chip input anti-aliasing filter is
included to reduce external system
costs.
The devices specified frequency
range is from 5 MHz to 65 MHz, with
an output P1dB > 67 dBmV through
a 1:1 impedance-ratio transformer.
A 3-wire digital serial bus controls
the variable gain, with gain control
available in 1 dB steps and a
nominal 59 dB gain range.
The MT1550 may be disabled via
an external control pin. The transmitdisable
mode not only minimizes
output noise by shutting off the
output stage, but also maintains its
output impedance at nominal levels.
Output transients are nominally less
than 16 mVp-p at 61 dBmV output
level during transmit enable/disable
switching.
Operating from a single 3.3 V
supply, the amplifier typically draws
247 mA at maximum gain or
minimum attenuation. Additional
internal circuitry reduces the
amplifiers power consumption
depending on gain setting.
Transmit-disable mode reduces the
typical current draw to 60 mA, while
shutdown mode further reduces it to
85