4-4 888-2587-001 4/18/11
WARNING: Disconnect primary power prior to servicing.
FM HD Radio System
Section 4 Boost Pro Theory of
4.2.2 A to D Converter
For monitoring the power amplifier, a 12-bit eight channel analog-to-digital converter is
used: TLV2548 from Texas Instruments. This converter is used to monitor the PA’s
forward power, reflected power, voltage, current, and temperature.
4.2.3 Power Supplies
There are two separate power supplies for the Boost Amplifier. The first is a single
+24Vdc 200W supply for the PA. The second is a triple-output 50W supply at +5Vdc,
+15Vdc and -15Vdc. Both power supplies are capable of 85-264VAC / 47-440Hz
inputs.
4.2.4 Front Panel
The front panel uses a 128x64 dot LCD, warning LEDs and buttons to interact with the
Boost Pro. The interface to the LCD is on the data bus.
4.2.5 Power Amplifier
The amplifier contains 3 stages of amplification. The first stage uses an LD-MOSFET
in Class A operation mode. Class of operation of following 2 stages depends on
modulation of amplified signal and transmitter configuration. The class of operation is
controlled by the binary level control signal that comes from system controller. When
the Boost Pro is used as a driver delivering RF signal to high power transmitter, the 2nd
two stages also operate in class A for better linearity.
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