特点
Dual Band RF Power Amplifier Control (LTC1957-2)
Internal Schottky Diode Detector with Improved Dynamic Range vs the LTC1757A
Wide Input Frequency Range: 850MHz to 2GHz
Autozero Loop Cancels Offset Errors and Temperature Dependent Offsets
Wide V
IN
Range: 2.7V to 6V
Allows Direct Connection to Battery
RF Output Power Set by External DAC
Fast Acquire After Transmit Enable
Internal Frequency Compensation
Rail-to-Rail Power Control Outputs
Power Control Signal Overvoltage Protection
Low Operating Current: 1mA
Very Low Shutdown Current: <1μA
Available in a 8-pin MSOP Package (LTC1957-1) and
10-Pin MSOP (LTC1957-2)
Pin Compatible with the LTC1757A-X
Improved Start Voltage Accuracy and Range
Improved PCTL Input Filtering
典型应用
描述
The LTC1957-1 is a single output RF power controller that is identical in performance to the LTC1957-2 except that one output (V PCA ) is provided. The LTC1957-1 can be used to drive a single RF or dual channel module with integral multiplexer. This part is available in an 8-pin MSOP package.
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 supply current and 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 <1μA.