The MAX4473 PA power control IC is intended for closed-loop bias control of GSM power amplifiers. The device facilitates accurate control of the current deliv- ered to the power amplifier (PA) through a control volt- age. The error amplifier senses the voltage drop across an external current-sense resistor placed between the supply and the PA. The output of the error amplifier adjusts the PA gain until the current is proportional to the power control voltage applied to the MAX4473. This unique topology is useful in time-division-multiple- access (TDMA) systems, such as GSM, where accurate transmit burst shaping and power control is required. User-selectable current sensing and gain setting resis- tors maximize flexibility. The MAX4473 operates from a single 2.7V to 6.5V sup- ply and typically draws 1.2mA of supply current. The error amplifier has a common-mode range that extends from 1V to VCC. The power control input and error amplifier outputs swing rail-to-rail. A low-power shut- down mode reduces supply current to less than 1µA and activates an on-board active pull-down at the error amplifier output. Fast enable/disable times of 0.9µs reduce average power consumption without compro- mising dynamic performance. The MAX4473 is avail- able in a space-saving 8-pin µMAX® package.
