LTC4401

The LTC4401-1 is a SOT-23 RF power controller for slow turn-on RF power amplifiers operating in the 300MHz to 2.7GHz range. The loop bandwidth is set at 250kHz to improve frequency stability when controlling slow turn-on RF power amplifiers such as the Conexant CX77301/CX77302, CX77304, CX77314, Anadigics AWT6107 and the RF Micro Devices RF3160.

RF power is controlled by driving the RF amplifier power control pins and sensing the resultant RF output power via a directional coupler. The RF sense voltage is peak detected using an on-chip Schottky diode. This detected voltage is compared to the DAC voltage at the PCTL pin to control the output power. The RF power amplifier is protected against high power control pin voltages.

Internal and external offsets are cancelled over temperature by an autozero control loop, allowing accurate low power programming. The shutdown feature disables the part and reduces the supply current to <10µA.

A dual control channel version (LTC4401-2) is also available in an 8-pin MSOP package.

Applications

• GSM/GPRS Cellular Telephones
• PCS Devices
• Wireless Data Modems
• U.S. TDMA Cellular Phones