Overview

The LA7790M is a QPSK data transmitter for digital cable TV applications. By integrating the I/Q quadrature modulator, RF amplifier, electronic volume control, mute control, and other functions onto a single chip, parts count is reduced and set size is miniaturized.

Features

• Maximum RF amplifier output level of +10 dBm (75Ω terminator), suitable for directly driving the cable.

• RF output frequency range of 5 to 70 MHz. Frequency range selection function permits broadband designs.

• Electronic volume control for direct-current control of RF output level.

• Muting ensures ample attenuation during periods with no transmission.

• Support for both internal and external bias for I/Q modulation inputs.

• Support for I/Q modulation frequencies up to 10 MHz. (typ: 500 mVp-p)

Functions

• I/Q quadrature modulator

• I/Q input bias power supply

• RF amplifier

• Varactor diode-based VCO

• Muting

• Electronic volume control

• Power-saving modes

• Switchable output frequency range

• Power supply voltage of 5 V (4.5 to 5.5 V)