Special-function ICs: Tuners

Notable among special-function ICs, some innovative tuners were announced within the past six months. These products raise the bar in performance and cost, while enabling manufacturers to deliver the best products to consumers.

One of the tuners announced was the Marvell (www.marvell.com) 88DE8500 hybrid silicon tuner with integrated Clear RF technology for the robust reception of analog and DTV signals. Available for worldwide use, the alignment-free tuner provides optimized automatic gain control (AGC) designed to ensure excellent picture performance for RF signals in terrestrial and cable analog and digital networks and to fine-tune and receive weak analog and digital signals for an acceptable picture performance. Featuring a 32-pin QFN package, low noise, and low power consumption, this hybrid silicon tuner is a competitive solution for slim DTVs and STBs.

The CMOS silicon tuner does not use external components like SAW filters, LNAs, and other tracking filters. The chip can tune to channels in the RF range from 40.5 to 1,002 MHz and convert those frequencies to a programmable low IF. The silicon tuner interfaces with the Marvell single-chip hybrid demodulators for Europe (88DE8020) and North America (88DE8010) to provide a complete RF receiver for DTV applications. When paired with Marvell single-chip demodulators, the complete RF receiver front-end provides robust reception for digital signals and good Audio/Video (AV) reception from analog terrestrial/cable networks. The tuner can also be interfaced to demodulators from third parties.

NXP (www.nxp.com) offers the TDA18272 silicon tuner, which supports all analog and digital TV standards worldwide. It comes in a 40-pin 6 x 6-mm package and integrates RF tracking filters, oscillators, IF selectivity, and wide-band gain control, eliminating the need for external components such as SAW filters or baluns. Based on a master/slave architecture tuner is manufactured under the company’s zero-defect program, which enables manufacturers to simplify product assembly and supply-chain management. Additional features include a single 3.3-V suppply voltage, an I2 C-bus interface, and a IF output range from 3 to 5 MHz.

Also recently announced, MaxLinear (www.maxlinear.com) presented the MxL751SM single-chip diversity tuner and ISDB-T 1-Segment (1-Seg) demodulator for mobile and portable TV applications that improve mobile TV reception without external antenna.

Most mobile TV designs have an external whip antenna to improve reception in dense urban or high-speed environments. These external antennas are expensive, break easily, and prevent waterproofing the handset. Manufacturers have also tried to use a single internal antenna, but the loss of sensitivity within the device has required costly, highly complicated design work-arounds.

With dual RF inputs, a diversity combiner, and 1-Seg demodulator, the MxL751SM is designed to deliver the sensitivity required to meet these challenges. Dynamic switching between diversity and single-channel modes is built into the device, and all channel filtering is integrated along with providing digital carrier and timing recovery. Measuring only 3.5 x 3.5 mm in a 49-pin WLCSP package, the part consumes 50 mW and supports a tuning range of 470 to 806 MHz.

Christina Nickolas