Other Parts Discussed in Thread: AFE58JD18
Tool/software:
Hi Team,
Question 1
When ADC directly drive LVDS output pins, that is, Digital Demodulator is bypassed, each input channel can drive its corresponding LVDS pair and data rate on LVDS pair is Fs * 14 bps, where Fs is sampling frequency and with 14bit per sample.
Further, Data from 8 input channels can also output from 4 LVDS pairs, while data rate on each LVDS pair doubles, that is up to Fs * 14 * 2 bps.
The LVDS sharing rule is
Ch1 + ch2 to LVDS3(D3P/N)
Ch3 + ch4 to LVDS4(D4P/N)
Ch5 + ch6 to LVDS5(D5P/N)
Ch7 + ch8 to LVDS6(D6P/N)
Is the above right?
Question 2
I prefer less PCB routing and I do NOT want a higher data rate on the LVDS. So I decide to use the Digital Demodulator. When using Digital Demodulator, every 2 input channel can also share 1 LVDS pair. But sharing rule seems to change as follows
Ch1 + ch2 to LVDS1(D1P/N)
Ch3 + ch4 to LVDS3(D3P/N)
Ch5 + ch6 to LVDS5(D5P/N)
Ch7 + ch8 to LVDS7(D7P/N)
And what I care most is, CAN I achieve a significant decrease of data rate with a large decimation factor M ? That is, only effective down-sampled data is transmitted through the LVDS line.
e.g. ( Fs /M ) * 2 * 16 * 2
where ( Fs /M ) is the equivalent sampling rate after decimation, * 2 (I/Q 2 data per sample), * 16 (16bit per I and Q data), finally * 2 represents 2 adjacent channels sharing the same LVDS pair.
Is that right?