AT&T to market European voice-to-antenna GSM hardware platform

BERKELEY HEIGHTS, N.J. -- AT&T Microelectronics today disclosed it will market a highly integrated 3-Volt hardware solution for next generation GSM digital cellular telephones.

The new Sceptre(TM) GSM hardware platform merges in five ICs the majority of the radio and baseband functions for the GSM (Global Standard for Mobile Communications) pan-European digital cellular standard. The devices will perform the radio frequency (RF) transceiver function, power amplification, digital/analog conversion and digital voice and baseband processing for a ter- minal's physical layer.

"The GSM hardware platform is designed for simplicity, economy and marketability," said Randall Fahey, product manager for European digital cellular processors. "Manufacturers will be able to reduce their time to market with a modular design which addresses the number one concern of the end user--low power consumption." He noted that the 3-Volt Sceptre GSM hardware platform can achieve talk times of up to four hours, and standby times of several days, from a three-cell battery.

The Sceptre GSM hardware platform combines AT&T's expertise in several key technologies. "By drawing on our know-how from RF design, IC development, algorithm design and digital signal processing, we can help our customers to quickly and efficiently address this market of 1.5 billion potential users," Fahey said.

"Our goal was to greatly reduce the component count, thereby reducing overall size and system cost," added Ren Jenkins, product manager for high performance ICs. He explained that RF tasks within the Sceptre GSM hardware platform are handled by a transceiver, a power amplifier and a power amplifier controller, while the baseband section consists of a digital/analog conver- sion and the new DSP1618 digital signal processors. As an il- lustration of the high level of integration, Jenkins said that the transceiver is the first 3-Volt radio IC to combine a trans- mit modulator, receiver, frequency-agile synthesizer and two local IF oscillators.

The first components in the hardware platform are sampling to qualified customers now. Production quantities for the entire hardware platform will be available 4Q94 and will be priced well under $100 in OEM quantities.

For product literature about AT&T's Sceptre GSM hardware platform, customers should call the AT&T Microelectronics Customer Response Center, 1-800-372-2447 Dept. P14 (in Canada, 1-800-553-2448 Dept. P14); FAX number +1-610-712-4106 (especially for customers outside of North America); or by writing to AT&T Microelectronics, Dept. AL-500404200, 555 Union Boulevard, Allen- town, Pa. 18103.

AT&T Microelectronics offers a full line of high performance components and electronic systems to original equipment manufac- turers for applications in network computing, telecommunications, cellular/wireless and video. Included in the product line are CMOS, Bipolar, GaAs and High Voltage custom and standard products, communications devices, graphics and speech processors, multi-chip modules, frequency control, interconnect products, lightwave products, and power supplies.

AT&T Microelectronics' five-chip set, the Sceptre(TM) hard- ware platform is the world's most highly integrated solution for GSM cellular handsets. The five devices, working from a minimum 2.7V supply, include an advanced baseband signal processor, op- timized to implement the complete GSM layer 1 protocol at less than half the clock rate required by a standard DSP. This is complemented by the world's first completely integrated GSM RF transceiver device.

The devices are all packaged in low profile packages, and consume only 724mW in talk mode, and 31mW in standby mode. This can yield a telephone working from a three-cell battery, with a talk time of four hours, and standby time of up to three days. The Sceptre solution supports both data and voice services, and is half-rate ready.

BASEBAND PROCESSING

The baseband signal processor effectively implements two op- timized processors on a single device. A dedicated Viterbi error-correction co-processor, which functions in parallel with the processor core, accelerates the GSM error correction and equalizer functions by a factor of ten. This dedicated engine enables the device to perform all of the processing required at less than half the clock speed of a standard DSP, thus cutting power consumption.

The signal processor chip yields 26MIPS at 2.7V, while main- taining low power consumption of less than 3.3mW/MIPS. An ad- vanced on-chip shared memory architecture allows the two proces- sors to intercommunicate with very little overhead.

SIGNAL CONVERSION

The interface between the radio and digital baseband signal processor is handled by a conversion signal processor (CSP). The CSP integrates the complete A/D and D/A functions for both voiceband and baseband, a GMSK modulator, and event timing and control state machines.

RADIO TRANSCEIVER

AT&T's Sceptre transceiver device integrates the GSM trans- mit and receive functions on a single IC. It includes a single frequency-agile fast-settling frequency synthesizer, allowing it to switch between transmit and receive frequencies without missing TDMA timeslots. The device implements the interface between baseband processing and the power amplifier stage, al- lowing users to build a finished handset using only one IF (in- termediate frequency), reducing receive filtering costs.

The receive path includes an RF mixer, digital gain- controlled IF amplifier, and a quadrature demodulator. The transmit path includes an offset oscillator mixer and quadrature modulator with an accurate 90-degree phase splitter. Two fixed frequency PLLs (phase locked loops) generate the LO (local oscil- lator) frequencies. The transceiver includes logic control for power down modes to minimize supply current.

POWER MANAGEMENT

The demanding power ramp and level control requirements of GSM are achieved with minimum supply current through a two-chip power amplifier-PA controller combination. The PA is a high- efficiency monolithic GaAs IC with output power control, operating in conjunction with the silicon power control IC to meet the GSM output power mask. The power controller IC also provides the negative gate bias voltages required by the power amplifier, eliminating the need for an external DC/DC converter, cutting component count, and reducing system cost and overall size.

BASICS OF THE GLOBAL SYSTEM FOR MOBILE COMMUNICATION

GSM is the European standard for digital cellular communica- tions. Controlled by ETSI (European Telecommunications Standards Institute), the GSM standard now has worldwide acceptance in more than 40 countries, with a total of 1.5 billion potential users.

GSM uses digital technology to ease the overcrowding in cur- rent analog cellular networks. Users of current generation cell- phones know such networks can easily become overstretched in high-traffic areas. But the use of digital technology also has other important benefits: a GSM handset can be used in any coun- try with a GSM network, both for making and receiving calls; digital technology makes it possible to integrate voice and data services; and transmission is secure, since both voice and data are carried in a coded format.

GSM is winning strong acceptance among customers, as evidenced by the fact that 25 live networks were in operation in 17 countries as of January. In Europe alone, the number of sub- scribers has grown to 1.2 million in just 18 months.

GSM handset design presents an unprecedented technical chal- lenge. Components must be low-cost, in keeping with the require- ments of a high-volume, mass market end-product. To maximize talk-time and standby-time, power consumption must be kept to an absolute minimum, even though, when in use, the handset must per- form some 40 million digital operations every second. To find market acceptance, the handset must be as small as possible, re- quiring not only fine-pitch, low-profile devices, but also low voltage, low-power operation, reducing the space required for batteries.

With expertise in the core technologies which have ac- celerated wireless communications, AT&T Microelectronics has ad- dressed these challenges by tapping its digital signal processing (DSP), radio frequency (RF) and integrated circuit (IC) know-how to develop an optimized end-to-end solution for GSM terminal manufacturers.

The resulting Sceptre(TM) GSM platform features a highly in- tegrated set of fine-pitch, low-profile devices, which, thanks to their low-voltage, low-power operation, reduce the space and weight requirements for batteries. The five devices perform all of the key handset functions from microphone to antenna. The devices support both GSM voice and data services, and are "half- rate ready"--meaning that they are designed to cope with future GSM coding developments which will further increase the maximum number of users per GSM cell.