1998-06-15 , S/IC-2025/43
Product News From Philips Semiconductors

Radio Frequency (RF) chip set shrinks components for IS-136 and digital communication applications

Philips Semiconductors today announced a highly integrated RF chip set aimed at designers of dual-band TDMA cellular (low-band) and PCS/DCS (high-band) phones. This chip set reduces the number of components needed to build a dual-band RF system by more than half. The  SA1920 RF receiver front-end, the  SA647 digital IF receiver, and the  SA9025 transmit modulator with fractional-N synthesizer comply with the TDMA IS-136 standard for dual-band, dual-mode (AMPS/TDMA) operation. By the year 2001, it is expected that more than 50 percent of all new mobile phones will support dual-band operation.

The SA1920 RF receiver front-end integrates both cellular and PCS low noise amplifiers (LNA) and down conversion mixers. A PCS-band image reject mixer, however, eliminates the need for an external band pass filter between the LNA and mixer. An on-board doubler supports the use of a single external voltage-controlled-oscillator (VCO) for both cellular and PCS bands. In addition, the SA1920 includes control logic, power down mode circuitry, and input and output buffers to further reduce external glue components and improve ease-of-use. The SA1920 also supports multiple cellular (AMPS, TDMA, GSM) and PCS (TDMA, PCS1900, DCS1800) standards for multi-mode phones.

The SA9025 combines a 900 MHz transmit modulator with a 2.2 GHz fractional-N dual synthesizer and offset loop synthesizer on the same IC. The variable gain pre-driver amplifier delivers +10.0 dBm output power, which attenuates up to 46 dB in 0.18 dB steps. The dual synthesizer uses a fractional-N first local oscillator (LO) divider that operates to 2.2 GHz, providing fast switching in narrow-band applications. An integer type second LO divider operates up to 500 MHz. A third synthesizer provides the offset frequency needed between transmit and receive bands. The SA9025 also includes a three-wire serial interface for programming and power down modes. By using an external upconversion mixer, a PCS frequency signal can be obtained for high-band operation. Both the SA1920 and SA9025 are available in a 48-pin plastic low profile quad flatpack (LQFP) package.

An IF receiver for portable digital and TDMA applications, the SA647 integrates an LNA, mixer, IF amplifier, IF limiter, fast receive signal strength indicator (RSSI) and oscillator in a single package. The LNA, integrated at the IF input, increases system sensitivity with improved noise performance. The SA647 has a RSSI dynamic range of 85dB and a system gain of more than 110dB. The SA647 is available in a 20-pin thin shrink small outline package (TSSOP).

The SA1920 is priced at $3.32 US, the SA9025 is priced at $7.73 US and the SA647 is priced at $2.38 US, in quantities of 10k pieces. All three ICs are in production and available for immediate sampling through Philips Semiconductors.

IS-136 is the TDMA digital cellular specification, which provides seamless cellular service between the 800 MHz cellular and the 1900 MHz PCS bands. It specifies the addition of a digital control channel and provides an improved speech coder, new cellular features and protocol additions, which allow greater mobility management and better cellular service.

Philips Semiconductors, a division of Philips Electronics NV, headquartered in Eindhoven, The Netherlands, is the ninth largest semiconductor supplier in the world and the third largest supplier of discretes in the world. Philips Semiconductors' innovations in digital audio, video, and mobile technology position the company as a leader in the consumer, multimedia and wireless communications markets. Sales offices are located in all major markets around the world and are supported by systems labs.