LTC4402

The LTC4402-2 is a multiband RF power controller for RF power amplifiers operating in the 300MHz to 2.4GHz range. The LTC4402-2 has two outputs to control dual T_X PA modules with two control inputs. An internal sample and hold circuit enables the LTC4402-2 to be used with AM modulation via the carrier or PA supply. The input voltage range is optimized for operation from a single lithium-ion cell or 3x NiMH.

RF power is controlled by driving the RF amplifier power control pins and sensing the resultant RF output power. 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 LTC4402-1 is a single output RF power controller with identical performance to the LTC4402-2. The LTC4402-1 has one output to control a single T_X PA or dual T_X PA module with a single control input and is available in an 8-pin MSOP package.

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

Applications

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