RF5117
Power sensing is implemented with the PWR SEN and PWR REF lines. The outputs of these pins are transistor collec-
tors and need to be pulled up to the supply through a resistor. PWR REF provides an output current proportional to the
output stage bias current, and PWR SEN provides an output current proportional to the total (RF and bias) current of the
output stage. The pull-up resistors convert these currents to voltages, and the voltage difference between these two pins
is proportional to the RF current. See the graph, “V
REF
-V
SENSE
versus P
OUT
”, for the response of this signal. This differ-
ence signal can be fed to a power control circuit elsewhere in the end product, or it can be processed at the PA with addi-
tional circuitry and used to adjust the V
REG
voltage(s) to implement automatic level control. Contact RFMD Sales or
Applications Engineering for additional data and guidance in using this feature.
The RF5117 has primarily been characterized with a voltage on V
REG1
and V
REG2
of 2.7VDC. However, the RF5117 will
operate from a wide range of control voltages. If you prefer to use a control voltage that is significantly different than
2.7VDC, contact RFMD Sales or Applications Engineering for additional data and guidance.
Rev A7 041007
2-577
RFMD [ RF MICRO DEVICES ]
