Datasheet

DS_1903_032 73M1903 Data Sheet
Rev. 2.1 19
Figure 6: Overall Receiver Frequency Response
Figure 7: Rx Passband Response
It is important to keep in mind that the receive signal should not exceed 1.16 Vpk-diff for proper
performance for Rxg=11 (0 dB). In particular, if the input level exceeds a value such that one’s density of
RBS exceeds 99.5%, sinc
3
filter output will exceed the maximum input range of the decimation filter and
consequently the data will be corrupted. Also for stability reasons, the receive signal should not exceed
1.16 Vpk differentially. This value is set at around 65% of the full receive signal of 1.791 Vpkdiff at
RXAP/RXAN pins that “would” corresponds to ASDM putting out all ones.
Figure 8 and Figure 9 show the spectrum of 1 kHz tone received at RXAP/RXAN of 1.16 Vpk-diff and
0.5 kHz and 1.0 kHz tones of 0.6 Vpk-diff each, respectively for Fs=8 kHz. Note the effect of FIR
suppressing the noise above 4 kHz but at the same time enhancing (in order to compensate for the
passband droop of sinc
3
filter) it near the passband edge of 4 kHz.