News | June 1, 1999

Mitel Develops RF Front-end Solution for Satellite Set-Top Box Design

Highly integrated RF front-end solutions are required in high-frequency industries. However, in the satellite set-top box market, where competition is running high, these solutions are not only a requirement, they are a key to survival.

In an effort to meet the needs of engineers, Mitel Semiconductor (Kanata, ON) has released an RF front-end solution for satellite set-top box designs. In particular, the new solution, called SNIM3, is targeted at digital satellite service (DSS) and digital video broadcast (DVB) designs.

The new solution includes four ICs: the SL1925 direct conversion IC, the SP5769 single-chip phase-locked loop frequency synthesizer, the VP310 quadrature phase-shift keying (QPSK)/forward error correction (FEC) channel decider, and the SL1914 low-noise amplifier (LNA).

The SL1925 is a wideband quadrature converter that is designed for satellite tuners operating in the 950 to 2150 MHz range. This device contains all of the elements necessary, with the exception of a local oscillator, to fabricate an in-phase/quadrature (I/W) phase splitter and downconverter for systems containing an RF automatic gain control (AGC).

Housed in an NP28 package, the SL1925 sports a 19 dB input noise figure, 55 dB maximum conversion gain, and 20 dB minimum conversion gain. The product also provides 0.2 dB gain match up to 22 MHz, 0.7 deg. phase match up to 22 MHz, 0.5 dB gain flatness, and a 103 dBµV input 1-dB compression point.

The SP5769 is a single chip PLL frequency synthesizer designed for tuning systems up to 3 GHz. The IC's RF preamplifier interfaces directly with the RF programmable divider. The comparison frequency is obtained either from an on-chip crystal-controlled oscillator or from an external source. The oscillator frequency or phase comparator frequency can be switched to the REF/COMP output, providing a reference for a second frequency synthesizer.

The synthesizer is controlled via an I2C bus and is fast mode compliant. It can be hard wired to respond to one of four addresses to enable two or more synthesizers to be used on a common bus.

The VP310 QPSK/FEC channel decoder IC integrates dual analog-to-digital (A/D) converters and an FEC into a single package. This IC receives analog I and Q signals from the tuner, digitizes and demodulates the signal, and implements the complete DVB/DSS FEC and de-scrambling function. It also provides automatic gain control to the chip set's RF devices.

The channel decoder provides on-chip digital filtering in order to support 1 to 45 Mbaud symbol rates. The IC also conforms to the EBU specification for DVB operation and the DirecTV specification for DSS operation.

The SL1914 LNA rounds out the SNIM3 RF front end chip set. This LNA is an optional IC that enhances the front-end design. According to Mitel, the product replaces approximately 20 RF passive components in order to reduce the number of external components required for chip set operations. Passive components eliminated include an IF oscillator, an IF mixer, and a surface-acoustic-wave (SAW) filter.

The SNIM3 RF front-end chip set can be integrated on a printed circuit board (PCB) measuring 35 x 110 mm. It can also be implemented on a four-layer, two-sided PCB that can accommodate a variety of applications including PC Cards and TV chassis.

A reference design is provided free of charge to customers designing SNIM3 into their products. This reference design includes a database of layout files, schematics, a bill of materials, driver software, and a PC-based evaluation kit/development environment.

Mitel did not release specific pricing information on the chip set. However, the company claims that a complete RF module can be built for under $10 in 100,000 volumes. For more information, contact Mitel at 613-592-2122.