U2731B Datasheet, PDF (1/25 Pages) ATMEL Corporation – DAB ONE- CHIP FRONT END

Features
• 8.5 V Supply Voltage
• Voltage Regulator for Stable Operating Conditions
• Microprocessor-controlled Via a Simple Two-wire Bus
• Two Addresses Selectable
• Gain-controlled RF Amplifier with Two Inputs, Selectable Via a Simple Two-wire Bus
Control
• Balanced RF Amplifier Inputs
• Gain-controlled RF Mixer
• Four-pin Voltage-controlled Oscillator
• SAW Filter Driver with Differential Low-impedance Output
• AGC Voltage Generation for RF Section, Available at Charge-pump Output
(Can Also Be Used to Control a PIN Diode Attenuator)
• Gain-controlled IF Amplifier
• Balanced IF Amplifier Inputs
• Selectable Gain-controlled IF Mixer
• Single-ended IF Output
• AGC Voltage Generation for IF Section, Available at Charge-pump Output
• Separate Differential Input for the IF AGC Block
• All AGC Time Constants Adjustable
• AGC Thresholds Programmable Via a Simple Two-wire Bus
• Three AGC Charge Pump Currents Selectable (Zero, Low, High)
• Reference Oscillator
• Programmable 9-bit Reference Divider
• Programmable 15-bit Counter 1:2048 to 1:32767 Effectively
• Tristate Phase Detector with Programmable Charge Pump
• Superior Phase-noise Performance
• Deactivation of Tuning Output Programmable
• Three Switching Outputs (Open Collector)
• Three D/A Converters (Resolution: 8 Bits)
• Lock Status Indication (Open Collector)
Electrostatic sensitive device.
Observe precautions for handling.
DAB One-chip
Front End
U2731B
Description
The U2731B is a monolithically integrated Digital Audio Broadcasting one-chip front
end circuit manufactured using Atmel’s advanced UHF5S technology. Its functionality
covers a gain-controlled 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 synthesizer. 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 switch-
ing outputs can be addressed. A reference signal which is 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 digi-
tally controlled by means of on-chip 4-bit D/A converters. All functions of this IC are
controlled via a simple two-wire bus.
Rev. 4671C–DAB–06/04