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Integrated RF LDMOS bias controllers debut

Posted: 08 Apr 2009 ?? ?Print Version ?Bookmark and Share

Keywords:LDMOS RF? bias controller? A/D D/A interface?

Maxim Integrated Products has introduced the MAX1385/MAX1386/MAX11008 dual RF laterally diffused metal oxide semiconductor (LDMOS) bias controllers. At 7mm x 7mm, these devices are claimed to be the smallest LDMOS bias controllers to integrate all of the A/D and D/A interfaces and logic functions required for cellular base station control, according to the company. The MAX1385/MAX1386/MAX11008 are suited to bias the power-amplifier power transistors employed in CDMA, GSM, Edge and UMTS cellular base stations.

These bias controllers integrate all the functions needed in a PA signal chain to achieve 25?V (MAX1385/MAX1386) or 50?V (MAX11008) of resolution for self-calibration. The MAX1385/MAX1386 provide two gate-drive channels, each consisting of an 8bit coarse DAC, a 10bit fine DAC and a gate-drive amplifier with a gain of 2 (MAX1385) or 4 (MAX1386). These channels generate a positive gate voltage to bias LDMOS devices, allowing up to 18bits of resolution. Each of the MAX11008's two gate-drive channels integrates a 12bit DAC to generate this positive gate voltage.

The MAX1385/MAX1386/MAX11008 offer a 7-channel, 12bit ADC, which includes three channels for temperature measurement. In addition, each IC includes dual high-side current-sense amplifiers (32V, CMRR 90dB), which offer up to 0.5 percent accuracy and 1 least-significant-bit linearity at 12bits. These high-side current-sense amplifiers feature programmable gains of 2, 10 and 25 to monitor the LDMOS drain current over the range of 20mA to 5A. The temperature sensor offers 0.25C resolution with up to 1C accuracy.

Pricing starts at $6.20 (1,000-up, FOB USA).

- Ismini Scouras

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