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3. Baseband Chipset
ZD1211 integrates WLAN MAC controller, base-band processor and USB 2.0 interface in
single chip. ZD1211 needs a 32K bit or 64K bit serial EEPROM to provide the card identification
on booting stage and RF information on operation. The interface also provides software interface
to read and write EEPROM. USB 2.0 interface is fully compatible to 480M USB high speed
mode and 12M full speed mode. It integrates USB 2.0 physical layer transceiver and
controller in chip. The embedded microcontroller and serial EEPROM provide flexibility
for customization of card identification in USB enumeration. The behavior of LED may be
programmable by software on host system.
4. Transceiver and Front-end
The AL7230 is a 2.4/5GHz dual-band transceiver for 802.11a/b/g applications. There are
five main blocks – power amplifier, transmitter, receiver, synthesizer and three-wire
interface. And external two baluns transfer 2.4/5GHz power to antenna. The receiver
path includes two single-ended input Low Noise Amplifiers, down-conversion mixers
with DC-offset cancellation for both 2.4GHz and 5GHz band, and a variable gain
amplifier with a baseband low-pass filter without the external SAW filter.