ML2721 Datasheet, PDF (1/27 Pages) Micro Linear Corporation – Low IF Digital Cordless Transceiver

PRELIMINARY
ML2721 Low IF Digital Cordless Transceiver
GENERAL DESCRIPTION
The ML2721 can be used as a single chip digital cordless
telephone transceiver or general purpose Frequency Shift
Keying (FSK) radio transceiver. It is designed to work in
the 902 to 928MHz ISM band under FCC Part 15
regulations. The device integrates all the frequency
generation, receive and transmit functions for data rates
up to 1.5Mbps. A complete radio only requires the
addition of an antenna switch. Micro Linear’s ML2751 is
an integrated 100mW power amplifier and receive LNA
with transmit/receive PIN diode drivers, and it can be
used with the ML2721 for extended range capability.
The ML2721 contains a proprietary low IF receiver with
all channel selectivity. An image reject mixer brings the
915MHz RF signal down to a low IF frequency of
1.024MHz. Then all IF filtering, IF gain, and
demodulation is performed at 1.024MHz. This provides all
the benefits of direct conversion to baseband and
minimizes the need for RF filtering. Also, the ML2721 can
operate with either a low cost LC filter or a SAW filter.
A single 1.83GHz synthesizer is used for both the receiver
LO and the transmitter. The ML2721 transmitter modulates
the VCO with filtered data, and a driver amplifier
provides typically 0dBm at 915MHz. The VCO and PLL
incorporate the resonator, the active devices, and the
tuning circuitry for a completely integrated function. An
internal post detection filter and data slicer are also
included.
The ML2721 contains its own DC regulation which allows
the IC to operate over a wide power supply voltage range.
It also has a simple baseband interface for transmit power
management, PLL control and detection, and RSSI
(Receiver Signal Strength Indication).
FEATURES
n Single chip 900MHz Radio Transceiver
n Fully integrated filters for all IF, FM discriminator and
data filtering
n Image reject mixer & proprietary Low IF architecture
reduce the need for RF filtering
n Integrated 1.83GHz frequency synthesizer with internal
VCO resonator
n TX/RX calibration for max power transmission
n Modulation compensation for improved sensitivity
performance
n PLL Programmed via 3-wire interface
n DC regulation for 2.7V to 5.0V operation (IC
performance is reduced from 2.7V to 3.2V)
n PLL lock detect output
n Analog Received Signal Strength Indication (RSSI)
output to baseband IC
n Easily upgradable for extended range with ML2751
APPLICATIONS
n 900MHz DSSS cordless phones
n 900 to 930MHz radio transceivers with ranges from 10
feet to 1000 feet and data rates to 1.5Mbps
n Single IC 900MHz low power radio
n FCC Part 15 compliant radio links
n Portable computer/PDA
n TDD and TDMA radios
PRELIMINARY DATASHEET ^{January, 2000}