ADI (also known as Analog Devices Inc.) was founded in 1965 and is probablly best known for its innovative DSP chipsets. More recently is has branched out into radio frequency devices. In the femtocell market, it offers an RF front-end chip for 3G femtocells.
The ADF4602 transceiver was announced in December 2008 with list price of less than $9 and requires few additional components.
The receiver is based on a direct conversion architecture. This architecture is the ideal choice for highly integrated wideband CDMA (WCDMA) receivers, reducing the bill of materials by fully integrating all interstage filtering. The front end includes three high performance, single-ended low noise amplifiers (LNAs), allowing the device to support tri-band applications. The single-ended input structure eases interface and reduces the matching components required for small footprint single-ended duplexers. The excellent device linearity achieves good performance with a large range of SAW and ceramic filter duplexers.
The integrated receive baseband filters offer selectable bandwidth, enabling the device to receive both WCDMA and GSM-EDGE radio signals. The selectable bandwidth filter, coupled with the multiband LNA input structure, allows GSM-EDGE signals to be monitored as part of a UMTS home basestation.
The transmitter uses an innovative direct conversion modulator that achieves high modulation accuracy with exceptionally low noise, eliminating the need for external transmit SAW filters.
The fully integrated phase lock loops (PLLs) provide high performance and low power fractional-N frequency synthesis for both receive and transmit sections. Special precautions have been taken to provide the isolation demanded by frequency division duplex (FDD) systems. All VCO and loop filter components are fully integrated.
The ADF4602 also contains on-chip low dropout voltage regulators (LDOs) to deliver regulated supply voltages to the functions on chip, with an input voltage of between 3.1 V and 3.6 V.
The IC is controlled via a standard 3-wire serial interface with advanced internal features allowing simple software programming. Comprehensive power-down modes are included to minimize power consumption in normal use.
ADI also provide an evaluation board to assist in design and testing of the component - see picture below (courtesy of ADI).
