Dual RF LDMOS Bias Controller with Nonvolatile Memory

Active: In Production.

The MAX11008 controller biases RF LDMOS power devices found in cellular base stations and other wireless infrastructure equipment. Each controller includes a high-side current-sense amplifier with programmable gains of 2, 10, and 25 to monitor the LDMOS drain current over a range of 20mA to 5A. The MAX11008 supports up to two external diode-connected transistors to monitor the LDMOS temperatures while an internal temperature sensor measures the local die temperature. A 12-bit successive-approximation register (SAR) analog-to-digital converter (ADC) converts the analog signals from the programmable-gain amplifiers (PGAs), external temperature sensors, internal temperature measurement, and two additional auxiliary inputs. The MAX11008 automatically adjusts the LDMOS bias voltages by applying temperature, AIN, and/or drain current samples to data stored in lookup tables (LUTs).

The MAX11008 includes two gate-drive channels, each consisting of a 12-bit DAC to generate the positive gate voltage for biasing the LDMOS devices. Each gate-drive output supplies up to ±2mA of gate current. The gate-drive amplifier is current-limited to ±25mA and features a fast clamp to AGND.

The MAX11008 contains 4Kb of on-chip, nonvolatile EEPROM organized as 256 bits x 16 bits to store LUTs and register information. The device operates from either a 4-wire 16MHz SPI™-/MICROWIRE™-compatible or an I²C-compatible serial interface.

The MAX11008 operates from a +4.75V to +5.25V analog supply with a typical supply current of 2mA, and a +2.7V to +5.25V digital supply with a typical supply of 3mA. The device is packaged in a 48-pin, 7mm x 7mm, thin QFN package and operates over the extended (-40°C to +85°C) temperature range.

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