BROADBAND AMPLIFIERS--MT1570 DOCSIS 3.0 UPSTREAM AMPLIFIER

The MicroStreamer MT1570 is
a low-cost, programmable power
amplifier IC that has been
developed specifically for use in
CATV upstream applications. This
amplifier can be combined with the
MT2170 tuner to create a complete
RF front end for a DOCSIS 3.0-
compatible cable modem. The
MT1570 supports four bonded
upstream data channels to be
simultaneously transmitted In
accordance with DOCSIS 3.0
requirements.
The MT1570 can pass all
DOCSIS requirements with outputs
as high as 64 dBmV for a QPSK
modulated signal. A 3-wire digital
serial bus is used to program the
variable gain in 1 dB steps over a
nominal range of 63 dB.
The IC operates from a nominal
supply voltage of 5.0 V and
dissipates a maximum of 2.2 W at
the highest gain setting and power
settings. The MT1570 has
programmable current modes that
can be used to adjust the bias
current of the output stage resulting
in reduced power consumption.
This is useful in applications that
can tolerate reduced linearity.
The MT1570 can be shutdown
via an external control pin or via the
3-wire serial bus. In this mode the
IC draws less than 100