Microtune Cuts Power For VoIP Designs

Microtune Inc. said it will help cable modem designers reduce overall power consumption in voice-over-Internet Protocol designs with the release Monday of a silicon tuner that consumes less than 1 watt.

The move to providing VoIP connectivity over cable modems poses a new power-management dilemma for the design community. While end users are willing to tolerate outages in their mobile-telephony devices, they scoff at the notion of a land line phone going down. This perception is forcing cable operators to provide backup mechanisms that allow phone service to continue even if a power outage occurs."The goal is to support eight hours of operation in the case of a power outage," said Greg Zancewicz, director of product marketing at Microtune.

To provide backup, many cable equipment vendors are placing battery mechanisms on their modem designs to ensure system up-time. But to ensure these backup systems can hit the 8-hour mark and beyond, designers are pushing silicon vendors for components with lower power-dissipation figures.

Microtune's MT2060 silicon tuner delivers a power consumption figure of 800 mW, vs. 1.3 to 1.5 W in its earlier designs, Zancewicz said. Integration and a move to a silicon germanium process enabled the company to take this number to below 1 W, he added.

On the integration front, Microtune has moved from a differential input to a single-ended input, thus eliminating the need for an input balun. Additionally, the company has pulled in the first intermediate-frequency (IF) filter, thus reducing board space and power consumption. This integration, Zancewicz said, resulted in a 25 percent space reduction over past tuner designs.The MT2060 is developed around a dual-conversion architecture. Signals fed into the chip at 800 MHz are immediately converted to 1.2 GHz, where adjacent-channel noise can be removed. The signals are then converted down to a lower IF-usually in the 30- to 50-MHz range-where additional noise is removed. Signals are then handed off through the output of a chip through a common interface to a digital demodulator.

Delivered in a 0.25-inch-square package, the MT2060 is sampling now, with initial production slated for the third quarter. The tuner is priced at $5 in 10,0000-unit volumes.