BROADBAND AMPLIFIERS--MT1560 UPSTREAM AMPLIFIER

The Microtune? MT1560 is a lowcost
programmable-gain power
amplifier IC for use in CATV
upstream applications. The MT1560
is a 3.3 volt part optimized for the
DOCSIS 2.0 upstream standard.
The devices specified frequency
range is from 5MHz to 65MHz, and
can output 67dBmV through a 1:1
impedance-ratio transformer. A 3-
wire digital serial bus controls the
variable gain, with gain control
available in 1dB steps and a
nominal 59dB gain range.
The MT1560 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 16mVp-p at 61dBmV output
level during transmit enable/disable
switching.
Operating from a single +3.3V
supply, the amplifiers typical
current draw at maximum gain, or
minimum attenuation, is 212mA.
Additional internal circuitry reduces
the amplifiers power consumption
depending on gain setting.
Transmit-disable mode power
supply current is reduced to a
nominal of 18mA. A shutdown mode
further reduces current to a nominal
of 80