Maxim Integrated Products’ MAX11014/MAX11015 ICs 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 (LUTs) that can be used to store temperature and drain-current compensation data.

The MAX11014/MAX11015 are unique in their 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 mV to 625 mV 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 successive-approximation-register (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, 2.5 V 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.

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). They operate from a 4.75 V to 5.25 V analog supply, a 0.7 V to 5.25 V digital supply, and a -4.5 V to -5.5 V gate-drive supply. The MAX11014/MAX11015 are available in 48-pin, thin QFN packages. Prices start at $10.60 for 1000-unit quantities.