The following figure shows the principle operation of the antenna tuning integrated into
the ATA8510/15. This feature is intended for
use together with magnetic loop antennas at moderate power levels.Figure 3-35. Antenna Tuning
A TXMode impedance transformation network, consisting of L3 and C9,
matches the 50Ω load impedance from the loop antenna to the optimum load impedance
needed for the power amplifier including the parasitics of the SPDT RF switch (see RF_OUT Matching).
An RXMode impedance transformation network consisting of L1(L2),
C4(C3) transforms the input impedance of RFIN_LB(HB) to 50Ω
seen on SPDT_ANT (see RFIN Matching).
The antenna tuning integrated into the ATA8510/15 is able to tune the resonance frequency of the loop antenna with
minimal impact on impedance transformation by adjusting the internal tuning capacitance
CTUNE at the end of the antenna.
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