Modulator For TETRA Systems Features Low, Far-Out Noise Floor

The RF2485 quadrature modulator for Terrestrial Trunked Radio (TETRA) systems is designed to address the needs of TETRA base station and handset designers. Designed for TETRA use over the 200 to 600 MHz band, the RF2485 features a broadband noise floor of -149 dBm/Hz typical at 5 MHz offset, along with ACPR of -48 dBc typical at 25 kHz. The RF2485 operates from a single 5V power supply and contains all of the components required to implement modulation functions, including differential amplifiers for the baseband inputs, a 90° hybrid phase splitter, limiting LO amplifiers, two balanced mixers, a combining amplifier, and an output RF amplifier capable of driving a 50 ohm load. Typical applications for the RF2485 include: digital and spread spectrum systems; GMSK, QPSK, DQPSK and QAM modulation; private mobile radio and TETRA systems; AM SSB, DSB modulation; and image-reject up-converters. Manufactured using a GaAs MESFET process, the RF2485 is offered in a SOIC-14 package priced at $2.90 each/10,000.