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RF MESFET bias controllers with 'unmatched level of integration'

Posted: 07 Mar 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Maxim Integrated Products? MAX11014? MAX11015? MESFET power device?

Maxim Integrated Products introduced the MAX11014 and MAX11015 ICs that set and control bias conditions for dual MESFET power devices found in point-to-point communication and other microwave base stations.

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 that can be used to store temperature and drain-current compensation data.

According to the company, the MAX11014 and MAX11015 are unique in their unmatched level of integration. 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 625mV range. External diode-connected transistors monitor the MESFET temperatures, while an internal temperature sensor measures the local die temperature. An internal DAC sets the voltages across the current-sense resistors by controlling the gate voltages. The internal 12-bit SAR ADC digitizes internal and external temperature, internal DAC voltages, current-sense amplifier voltages, and external gate voltages. Two of the eleven ADC channels are available as general-purpose analog inputs for analog system monitoring. An internal reference provides a well-regulated, low-noise, 2.5V reference for the ADC, DAC and temperature sensors while still allowing the flexibility to operate from the ADC's and DAC's individual external references.

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.

The two new bias controllers communicate over a 20MHz SPI-compatible 4-wire serial interface or a 3.4MHz I2C-compatible serial interface (pin-selectable). These devices operate from a 4.75V to 5.25V analog supply, a 2.7V to 5.25V digital supply, and a -4.5V to -5.5V gate-drive supply.

The MAX11014 and MAX11015 are available in 48-pin, thin QFN packages specified over the -40C to 105C temperature range. Prices start at $10.60 (1,000-up, FOB USA).

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