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Bias controllers target microwave basestations

Sunnyvale, Calif. — Maxim Integrated Products announced ICs that set and control bias conditions for dual MESFET power devices found in point-to-point communication and other microwave basestations.

The MAX11014 integrates closed-loop drain-current control for Class A MESFET amplifier operation, while the MAX11015 sets the MESFET gate voltage for Class AB operation. Both devices integrate SRAM look-up tables (LUTs) that can be used to store temperature and drain-current compensation data.

Each device includes dual, high-side, current-sense amplifiers to monitor the MESFET drain currents through the voltage drop across the sense resistors in the 0 to 625-millivolt range. External diode-connected transistors monitor the MESFET temperatures, while an internal temperature sensor measures the local die temperature. An internal digital-to-analog (D/A) converter sets the voltages across the current-sense resistors by controlling the gate voltages. The internal 12-bit SAR analog-to-digital (A/D) converter digitizes internal and external temperature, internal D/A converter voltages, current-sense amplifier voltages, and external gate voltages.

The MAX11014's gate-drive amplifier functions as an integrator for the drain-current control loop, while the MAX11015's gate-drive amplifier functions with a gain of -2 for Class AB applications. The current-limited gate-drive amplifier can be fast clamped to a programmable analog voltage independent of the digital input from the serial interface. Both the MAX11014 and MAX11015 include self-calibration modes to minimize error over time, temperature, and supply voltage.

 
 
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These two bias controllers communicate over a 20-MHz, SPI -compatible, 4-wire serial interface or a 3.4- MHz, I2C -compatible serial interface (pin-selectable).

The devices operate from a +4.75 V to +5.25 V analog supply, a +2.7 V to +5.25 V digital supply, and a -4.5 V to -5.5 V gate-drive supply.

The MAX11014 and MAX11015 are available in 48-pin, thin QFN packages specified over the -40°C to +105°C temperature range. Prices start at $10.60 (1000-up, FOB USA). Click here for the prelim data sheets.

Maxim Integrated Products Inc. , 1-800-998-8800, www.Maxim-ic.com.

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