ATR2731 Datasheet, PDF (2/26 Pages) ATMEL Corporation – DAB One-chip Front End

1. Description
The ATR2731 is a monolithically integrated Digital Audio Broadcasting one-chip front-end circuit
manufactured using Atmel’s advanced UHF5S technology. Its functionality covers a gain-con-
trolled RF amplifier with two selectable RF inputs, a gain-controlled RF mixer, a VCO which
provides the LO signal for the RF mixers, either directly or after passing a frequency divider, a
SAW filter driver, an AGC block for the RF section, a gain-controlled IF amplifier, an IF mixer
which can also be bypassed, an AGC block for the IF section, and a fractional-N frequency syn-
thesizer. The frequency synthesizer controls the VCO to synthesize frequencies in the range of
70 MHz to 500 MHz in a 16-kHz raster; within certain limits, the reference divider factor is fully
programmable.
The lock status of the phase detector is indicated at a special output pin; three switching outputs
can be addressed. A reference signal, generated by an on-chip reference oscillator, is available
at an output pin. This reference signal is also used to generate the LO signal for the IF mixer,
either by doubling the frequency or by using the reference frequency itself. Three D/A converters
at a resolution of 8 bits provide a digitally controllable output voltage. The thresholds inside the
AGC blocks can be digitally controlled by means of on-chip 4-bit D/A converters. All functions of
this IC are controlled via a simple two-wire bus.
2 ATR2731
4904A–DAB–03/06