Product category: Communications ICs (Wireless)
News Release from: Zarlink Semiconductor | Subject: ZLTM20250
Edited by the Electronicstalk Editorial Team on 24 January 2003
Multiband cellular transceiver mops up
60 parts
Zarlink Semiconductor has unveiled the world's first off-the-shelf, single-chip radio transceiver for cell phones used in multiband, multimode, 2G and 2.5G digital cellular networks.
Zarlink Semiconductor has unveiled the world's first off-the-shelf, single-chip radio transceiver for cell phones used in multiband, multimode, 2G and 2.5G digital cellular networks Zarlink's ZLTM20250 chip - the industry's smallest and most flexible commercial radio transceiver - is targeted primarily at handsets for GAIT overlay networks that add GSM capability and mobile Internet data services to existing TDMA/AMPS wireless infrastructure
This article was originally published on Electronicstalk on 7 Feb 2001 at 8.00am (UK)
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Multimode GAIT cellular networks are being deployed extensively across North America.
Zarlink's new transceiver eliminates about 60 separate components from GAIT cellphones, shrinking the size of the radio by more than half, and reducing bill of materials costs by up to 40%.
The device supports high-quality reception of all GAIT voice services, as well as high-speed data services based on the 2.5G GPRS and Edge platforms.
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Zarlink's is the first commercial cellphone radio that handles two-way data services at 384Kbit/s - the top Edge rate - without using external circuitry.
"As the first commercial GAIT chip to combine receive and transmit circuitry on one piece of silicon, and the only one with full-rate duplex GPRS/Edge, the ZL20250 offers unmatched integration and performance", said Derek Rye, cellular marketing manager, User Access business unit, Zarlink Semiconductor.
Zarlink's ZL20250 transceiver is the first off-the-shelf cellphone radio chip with full, two-way compatibility for 8PSK (eight-level phase shift keying), the high-density digital modulation scheme that gives Edge its fast, 384Kbit/s datarate.
GAIT radio chips from other vendors rely on separate external components for 8PSK uplinks.
In addition, Zarlink's transceiver supports the normal GMSK modulation technique used by GSM and GPRS applications.
The ZL20250 is also the first commercial single-chip, 2.5G cellphone radio transceiver.
Traditionally, cellular receive and transmit functions have been implemented on two or more chips to ensure that sensitive RF front-end receive circuits are isolated from transmit signals.
However, the ZL20250 integrates receive and transmit circuits on the same silicon chip by using a high-performance, two-stage receiver design to overcome these isolation issues.
The chip's receive circuitry has two IF inputs, one for GSM/GPRS/Edge, the other for TDMA/AMPS.
Incoming signals are mixed with synthesised local oscillator signals from an on-chip VHF VCO, amplified, and downconverted to the baseband frequency.
The ZL20250 receiver has integrated channel filters that allow the chip to connect directly to most baseband processors.
Other vendors typically implement these channel filters off-chip in complex, costly, and multicomponent analogue circuitry.
The transmitter on the ZL20250 is a highly linear circuit with a quadrature modulator, IF gain control, and a single-ended output.
The single-ended output delivers enough power to directly drive a two-stage power amplifier, eliminating the need for an external balun transformer.
The ZL20250 uses a high-performance, fractional-N synthesiser to control its UHF VCO, allowing it to switch rapidly between frequencies.
The radio gives designers control over power consumption, with programmable features to adjust receive and transmit currents to accommodate different operating requirements.
Zarlink's multimode ZL20250 transceiver operates in four key cellular frequency bands: 850, 900, 1800 and 1900MHz.
This quad-band capability allows the transceiver to support TDMA/AMPS/GSM/GPRS/Edge services in North America, as well as many GSM/GPRS/Edge operating environments in Europe and other regions.
The chip is fully compliant with the TIA/EIA IS-136 specification, and with protocols for GSM, Edge, and GPRS defined by ETSI.
The ZL20250 is entering volume production.
It is designed in an advanced SiGe BiCMOS process, and offered in a 56-pin MLP with dimensions of 8 x 8mm.
An evaluation board and API software support the chip.
In high volumes, the ZL20250 is priced at less than US $7.00.
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