JAJSPH5 December 2022 ADC3544
PRODUCTION DATA
The ADC3544 supports complex decimation by 2, 4, 8, 16 and 32 with a pass-band bandwidth of ~ 80% and a stopband rejection of at least 85 dB. Table 8-2 gives an overview of the pass-band bandwidth of the different decimation settings with respect to ADC sampling rate FS. In real decimation mode the output bandwidth is half of the complex bandwidth.
REAL/COMPLEX DECIMATION | DECIMATION SETTING N | OUTPUT RATE | OUTPUT BANDWIDTH | OUTPUT RATE (FS = 125 MSPS) | OUTPUT BANDWIDTH (FS = 125 MSPS) |
---|---|---|---|---|---|
Complex | 2 | FS / 2 complex | 0.8 × FS / 2 | 62.5 MSPS complex | 50 MHz |
4 | FS / 4 complex | 0.8 × FS / 4 | 31.25 MSPS complex | 25 MHz | |
8 | FS / 8 complex | 0.8 × FS / 8 | 15.625 MSPS complex | 12.5 MHz | |
16 | FS / 16 complex | 0.8 × FS / 16 | 7.8125 MSPS complex | 6.25 MHz | |
32 | FS / 32 complex | 0.8 × FS / 32 | 3.90625 MSPS complex | 3.125 MHz | |
Real | 2 | FS / 2 real | 0.4 × FS / 2 | 62.5 MSPS | 25 MHz |
4 | FS / 4 real | 0.4 × FS / 4 | 31.25 MSPS | 12.5 MHz | |
8 | FS / 8 real | 0.4 × FS / 8 | 15.625 MSPS | 6.25 MHz | |
16 | FS / 16 real | 0.4 × FS / 16 | 7.8125 MSPS | 3.125 MHz | |
32 | FS / 32 real | 0.4 × FS / 32 | 3.90625 MSPS | 1.5625 MHz |
The decimation filter responses are normalized to the ADC sampling clock frequency FS and illustrated in Figure 8-19 to Figure 8-28. They are interpreted as follows:
Each figure contains the filter pass-band, transition band(s) and alias or stop-band(s) as shown in Figure 8-18. The x-axis shows the offset frequency (after the NCO frequency shift) normalized to the ADC sampling rate FS.
For example, in the divide-by-4 complex setup, the output data rate is FS / 4 complex with a Nyquist zone of FS / 8 or 0.125 × FS. The transition band (colored in blue) is centered around 0.125 × FS and the alias transition band is centered at 0.375 × FS. The stop-bands (colored in red), which alias on top of the pass-band, are centered at 0.25 × FS and 0.5 × FS. The stop-band attenuation is greater than 85 dB.