Ghz Power Amplifier And Antenna Switch Circuit - Panasonic KX-TG5431BXS Service Manual

KX-TG5431BXS / KX-TGA542BXS

21.5. 5.8GHz Power Amplifier and Antenna Switch Circuit

This block amplifies power of 5.8GHz TX signal.
5.8GHz TX signal from 5.8GHz Converter circuit is filtered by 5.8GHz-BPF FL811, and amplified by Power amplifier (PA) block of
IC851, and then passes through internal 5.8GHz-BPF. After that, it is supplied to Antenna Switch block of IC851.
This block selects the TX 5.8GHz signal or RX 5.8G signal, and connect to Antenna terminal.
V_PA is approximately 4.0V at Base Unit, and 3.3V at Handset.
<Base Unit>
IC851 includes Switches for High frequency signals, and controlled by ANT0 signal and ANT 1 signal from DSP.
DSP is checking RSSI (Received Signal Strength Indicator) signal, and selects better condition Antenna from two antennas.
At the TX mode 5.8GHz TX signal from 5.8GHz PA block leads to selected Antenna terminal, at the RX mode 5.8GHz RX signal
from selected Antenna terminal leads to 5.8GHz LNA circuit.
<Handset>
IC851 includes Switch for High frequency signals, and controlled by PA_CONT signal and RX_EN signal from DSP. At the TX
mode 5.8GHz TX signal from 5.8GHz PA block leads to Antenna terminal, at the RX mode 5.8GHz RX signal from Antenna terminal
leads to 5.8GHz LNA circuit.
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