[Microtune, Inc.]

PRODUCT BRIEF

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 1.1 upstream standard. The MT1550 also includes an on-chip input anti-aliasing filter, thereby reducing external system costs.

The device’s 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 MT1550 may be disabled via an external control pin. The transmit disable 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 amplifier’s typical current draw at maximum gain, or minimum attenuation, is 259mA. Additional internal circuitry reduces the amplifier’s power consumption depending on gain setting.

Transmit-disable mode power supply current is reduced to a nominal of 62mA. A shutdown mode further reduces current to a nominal of 70μA.

The MT1550 is available in a 20-pin MicroLeadFrame? package with an exposed pad for the extended industrial temperature range of -40°C to +85°C.

FEATURES

? Integrated on-chip anti aliasing filter

? Maximum output level of 67dBmV

? Low power-up/down

transients of 16mV p-p typical at 61dBmV output

? Ultra low third harmonic distortion

? Single +3.3V supply

? 59dB gain range

? Gain programmable in 1dB steps

? Low transmit output noise floor: -50dBmV in 160kHz

? Low transmit-disable output noise: 1nV / √Hz

? Two power-down modes

? Primarily for set-top boxes

? DOCSIS 1.1 compatible

MT1550 APPLICATIONS

? Cable modems

? Telephony over cable

? Set-top box CATV