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The LMV248 RF power amplifier
controller allows simple implementation of transmit power control
loops in GSM and DCS/PCS and mobile phones. The LMV248 supports,
GaAs HBT and bipolar RF power amplifiers. The device operates from a
single supply of 2.5V to 5V. The LMV248 includes an error amplifier
with an input summing network, input and output band switches, input
filters, and output drivers. Analog input signals processed are:
- Coupler/detector voltages from GSM
and PCN band power amplifier outputs.
- Base band DAC ramp signal.
- Temperature compensation diode
voltages.
- Pre-bias voltage for faster PA
control.
Selection of the GSM or PCN output
driver is made using the GSM/PCN band select pin.
The On/OFF pin allows rapid power up
or shutdown of the device during Tx or Rx slots. In the off mode,
both output drivers are set low for PA shutdown. In the on mode,
the non-active driver will remain low for continued PA shutdown. A
single external capacitor/resistor combination is used to adjust
the closed loop frequency response.
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