NXP Semiconductors
AN11740
PN5180 Antenna design
AN11740
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Application note
COMPANY PUBLIC
Rev. 1.1 — 19 June 2018
345311
50 of 62
a. Type B response
b. Green: LMA (RefPICC input)
c. Blue: TX_ACTIVE (Trigger)
d. Yellow: unfiltered Q-Channel
e. Orange: BPSK_SUM
f. Type B response Zoom in
g. Green: LMA (RefPICC input)
h. Blue: TX_ACTIVE (Trigger)
i. Yellow: unfiltered Q-Channel
j. Orange: BPSK_SUM
Fig 44. Type B response with test signals
The major registers, which need to be adjusted properly, are:
6. RX_GAIN = 0…3
7. RX_HPCF = 0…3
8. MIN_LEVEL = 0…F
9. MIN_LEVEL_P = 0…F
The effect of changing the RxGain in combination with RX_HPCF can directly be seen in
the unfiltered I or Q channel signal.
The Fig 45 shows the same test case with the same LMA level and the same bandwidth
(HPCF), but just different settings for RxGain. On the left hand side, the RxGain is set to
2, on the right hand side the RxGain is set to 3 (maximum). Both the Q channel signal as
well as the BPSK_SUM signal show higher level of signal as well as higher level of noise,
when using a higher RxGain.
The Fig 46 shows the same test case with the same LMA level and the same RxGain,
but just different settings for RX_HPCF. On the left hand side, the RX_HPCF is set to 0,
on the right hand side the RX_HPCF is set to 3 (maximum). Both the Q channel signal as
well as the BPSK_SUM signal show lower level of signal as well as lower level of noise,
when using a higher HPCF (i.e. a lower bandwidth).
