Siemens cellular phone

MUNICH, GERMANY--Siemens AG is preparing to unveil a second generation cellular phone chipset at the upcoming Electronica '94 conference here in November. The new chipset, dubbed Gold Plus, is targeted at the European standard GSM (Global System for Mobile Communications) handheld, digital cellular phone markets.

In the Gold Plus chipset, Siemens added a speech codec (coder/decoder) and voice band converter functionality to its existing Gold chipset, and the A52 encryption algorithm has been included to address GSM Phase Two when it is adopted. Siemens will also introduce a companion gallium arsenide (GaAs) power MMIC (monolithic microwave integrated circuit) chip, the CGY 92, for GSM systems.

Siemens Semiconductor Group recently completed a restructuring program that put the group in the black "earlier than expected," according to Jurgen Knorr, member of the managing board of Seimens AG and head of the semicon-ductor group. The restructuring is the second leg of a three-phase program, the company said. The third phase will involve pursuing a business strategy focused on core competence, including chipsets and other products for the telecommunications market, that the company projects will enable it to generate better than average growth over the next few years.

The Gold Plus chipset includes three new baseband chips and a three-chip RF (radio frequency) front end (from the existing Gold chipset) together with the necessary components for the power amplifier--implemented either as a discrete solution or the CGY 92, a fully integrated MMIC covering the functionality between the output of the modulator and the antenna.

Klaus Knapp, senior director of Siemens and spokesman for the Siemens Semiconductor Group, said "The Gold Plus chipset is one of the first approaches to integrating as much as you can of a wireless cellular digital telephone on a chipset. We started with a 12-chip chipset, then reduced it to a nine-chip chipset two years ago (with the Gold chipset).

"Now it is a six-chip chipset, showing an even higher integration range. It can be used for 2.7 volts, and the lower power supply offers advantages in terms of the lifetime of the battery. Together with the CGY 92, it offers a compact solution that will cut the size and width of upcoming GSM phones," Mr. Knapp predicted.

The Gold Plus chipset consists of six chips including three new chips: a signal processor (PMB 2707), a controller chip (PMB 2706) and an analog chip (PMB 2905). Three chips from the previous Gold chipset are also included: the PMB 2240 transmitter, PMB 2405 receiver and PMB 2306 PLL (phase locked loop) IC.

The PMB 2707 is a digital signal processor with two DSPs and a total power of more than 50 MIPS. This chip is said to contain all the necessary algorithms and implements the channel and speed coding/decoding, equalization, GMSK modulation, baseband and voiceband filtering, data services and security encryption. In addition, it is prepared for the implementation of future extended GSM bands and half-rate algorithms as soon as these are fixed.

The PMB 2706 controller chip includes the same 16-bit microcontroller core as the present solution, enabling software upgrades. The instruction set supports low power operation. The extended address space for code and data allows control and man-machine software to be handled by the one chip. The system interface black supervises the RF section as well as the peripheral modules.

Siemens' PMB 2905 analog circuit is said to implement the baseband and voiceband A/D (analog to digital) and D/A converters. Additional converters are provided for power amplifier and battery supervision, Siemens said.

In the RF design, the higher integration offers all transceiver functions on three chips--transmit, PLL and receive. The transmit and receive functions are implemented in Siemens' B6HF 0.4-micron bipolar process technology. The functional blocks meet GSM requirements as well as PCN, according to Siemens, and are suitable for other vector modulation schemes worldwide.

The PMB 2240 transmitter circuit is comprised of a vector modulator, up-conversion mixer, an IF synthesizer, RF VCO and prescaler. The RF synthesizer is complemented by the PMB 2306 high performance PLL IC. The PMB 2405 receiver provides a one-chip conversion from the antenna directly to the baseband converter.

In addition to the six-chip Gold Plus chipset, OEMs will need a power amplifier, implemented either as a discrete components solution or as the CGY 92, a fully integrated GaAs power IC (MMIC) that Siemens is offering to complete a GSM system.

The CGY 92 provides an output of 32dBm at 3 volts, rising to as much as 35dBM at 5V. Apart from its application in GSM systems, it can also be used in other systems for the 900MHz band, for example AMPS systems. The input of the MMIC registers an impedance of 500hm, while the output can be adjusted, the company said.

The Gold Plus chipset will ship in quantity in early 1995, priced at $50 each. The CGY 92 GaAs power IC (MMIC) for GSM systems is sampling currently, and will be available for quantity shipment in 1Q95, priced comparable with existing solutions. Specific pricing has not been set yet, the company said.

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