In 1992 we produced the world's first single-chip baseband signal processor for GSM. This early start, combined with our knowledge in wireless personal communications, has enabled us to provide complete solutions to meet all your needs for the de facto wo rld digital standard GSM (900 MHz), and its PCN derivative DCS1800 (1800 MHz).
Our GSM/DCS1800 portfolio comprises complete, low-power solutions for manufacturers of handsets and modules. These solutions include total support (from system design to software for all GSM layers), and cover all functions from loudspeaker and microphone to antenna. Our products range from state-of-the-art chipsets to a complete RF and baseband module solution.
If you're new to GSM, the module solution will greatly ease your entry into this market. Furthermore, we offer:
All Philips Semiconductors solutions comply with the general specifications of the GSM digital cellular network.
Current GSM chipset
Our current chipset (see Fig.1) uses 5 V technology and has built-in power management to increase standby and talk-time. It performs all functions required for GSM phones and comes with complete hardware/software support. A fully operational demo-kit is a
vailable for system evaluation.
The RF transceiver performs all up-/down-modulation of the baseband and RF frequencies, respectively. It comprises: the PCA5075 (power amplifier controller), UAA2071 (RF transmitter), UAA2072M (RF receiver), UMA1018 (frequency synthesizer), NE602A (IF rec eiver) and the TDA8780 (logarithmic amplifier). The single-chip baseband interface (BBI; PCD5071) performs all AD/DA conversions of the baseband (IF) frequency and the GMSK modulation/demodulation.
The heart of our chipset is the GSM KISS baseband DSP (PCF5081). All GSM baseband signal-processing algorithms are handled in this single-chip RISC processor. The DSP communicates via three interfaces: a serial interface through the BBI to the RF section, a serial speech interface to the audio CODEC and a parallel interface to our 68000-based system controller. Signal processing is implemented in software using application-specific hardware to speed up execution of program modules.
The system controller (P90CL301) and TDMA timer (PCF5076) perform all the GSM layer 1 to layer 3 tasks and provide time-critical hardware signals. The smartcard interface (TDA8005) controls the display, keyboard and smartcard (SIM - Subscriber Identity Mo dule). Other components of the chipset comprise a program ROM and data RAM for the system controller, and a proprietary 14-bit audio CODEC (ARCOFI).
GSM module solution
Philips Semiconductors is also working on pre-fabricated and tested module solutions that offer you an alternative to packaged ICs and naked dice:
Our GSM module design, based on our current chipset, comprises a baseband and an RF module (see Fig.4 overpage). Virtually a turnkey solution, this design provides the basis of a handheld phone offering:
2nd generation GSM/DCS1800 chipset
With samples available in early 1995, this 3 V chipset uses low-power, low-voltage technology, is highly integrated and is suitable for DCS1800 PCN systems. This 8-chip solution (Fig.2) is the next milestone on the road to smaller digital phones. Key feat
ures include ICs fabricated in 0.5 m CMOS technology for the baseband and QUBiC (BiCMOS) technology for the RF part. The ICs are encapsulated in small TQFP packages.
In the RF section, three new ICs complement the existing PCA5075: the SA1620 RF transceiver, the SA1638 IF transceiver and the UMA1019 RF synthesizer. The new chipset has been developed with future systems in mind. Only minor changes are required to suppo rt DCS1800/PCS1900 or dual-mode and multi-mode handsets (e.g. GSM/DCS or GSM/DCS/DECT). The chipset supports high IF frequencies and allows simple, low-cost filters to be used for image-rejection.
The baseband and audio interface (PCD5072) is a new single-chip interface between the IF transceiver, the microphone and earpiece and the baseband processor. It integrates an audio CODEC and auxiliary AD/DA converters for AGC, AFC and power management. The new baseband DSP (PCF5083) includes the TDMA timer. Like the earlier PCF5081, an on-chip ROM contains firmware program modules to perform all necessary processing algorithms. Special attention has now been given to equalization to improve performance in hilly areas and fast-moving vehicles.
IS-54 (D-AMPS; TDMA) and IS-95 (CDMA)
Designed to address the problem of using existing channels more efficiently, IS-54 employs the same 30 kHz channel spacing and frequency bands (824-849 and 869-894 MHz) as the current North American analog cellular standard: AMPS. By using TDMA instead of
FDMA, IS-54 increases the number of users from 1 to 3 per channel (up to 10 with enhanced TDMA).
The IS-54 specification states that the digital handset and system must also support the analog AMPS system. Although it's early days for IS-54, forecasts indicate there will be over 1 million users in three years time. With experience from our low-power AMPS chipset, together with customer inputs, we've produced a 4-chip solution for an IS-54 RF/IF section.
IS-95 is another digital standard that uses the same frequency bands as AMPS and supports AMPS operation. This standard uses CDMA, employing spread-spectrum technology and a special coding scheme. This standard is at a very early stage but promises a thre efold increase in user capacity over IS-54. We'll keep you posted of developments in this area in future issues of this briefing.
IS-54 transceiver chipset
To compete with existing analog standards, a low power, highly integrated solution is a must for any digital standard to succeed. Our new chipset for IS-54 (see Fig.3) meets these criteria. The chipset combines all of the necessary RF and IF functions int
o four integrated devices: the SA601 RF front end, the SA637 digital IF receiver, the SA7025 dual frequency synthesizer and the SA900 I/Q transmit modulator.
These devices were designed as a system and therefore have interface levels which are matched, eliminating the need for additional buffers and interface devices. There is also a common high speed serial interface bus, making addressing the devices simpler . Additionally the frequency plan was designed to eliminate the need for an additional synthesizer and VCO loop. All of these features dramatically reduces the cost and size while improving the performance of the overall system. Although this is not the o nly IS-54 solution, our 4-chip configuration is the most integrated and easy to use chipset available today. For example, the SA900 provides I/Q modulators, the phase shifter, the VGA, a filter, control logic, clock distribution and more in a single IC. W e've also eliminated the need for two synthesizers by closely coupling the SA7025 and the SA900 so it is possible to use the main synthesizer to simultaneously generate receive and transmit signals.
The integration and connectivity of the chipset promote significant cost reduction. In addition, this integrated solution reduces the time to a final product by simplifying the design effort. The result is a smaller, cost effective, low-power phone that i s ultimately more attractive to the end users. Moving to a digital standard not only provides for increase in capacity, but offers the advantages of service integration. With the use of a digital modulation, other services such as data and fax can also be handled more easily over this system.
PCS
Future growth in PCS will fuel development of application-specific ICs for this new market.
PDC
Personal Digital Cellular is the Japanese standard for this area and is TDMA-based, operating in the 800 and 1500 MHz bands. Although PDC is continuously under development, the standard has not been adopted by many other countries so far. We do offer limi
ted support for this standard, such as our fractional-N frequency synthesizers (see New Products). And many of our standard products (microcontrollers, LCD drivers, frequency synthesizers, etc.) are also suitable for PDC. More information on our PDC-speci
fic products will be covered in future editions of this briefing.