SBAS745B December 2015 – January 2023 ADS54J66
PRODUCTION DATA
In this configuration, the DDC block includes a selectable N × fS / 16 complex digital mixer (n from –8 to +7) preceding the decimation-by-4 digital filter, so the IQ passband is approximately ±55 MHz (3 dB) centered at N × fS / 16. A positive value for N inverts the spectrum. Figure 7-15 shows the filtering operation in DDC mode 6. Table 7-7 shows corner frequencies of decimation filter in DDC mode 6. The decimation-by-4 filter is a cascade of two decimation-by-2 filters with frequency response shown in Figure 7-16 and Figure 7-17.
The stop-band attenuation is approximately 90 dB for in-band aliases from negative frequencies and approximately 55 dB for out-of-band aliases. The pass-band flatness is ±0.1 dB.
CORNERS | LOW PASS |
---|---|
–0.1 dB | 0.102 × fS |
–0.5 dB | 0.105 × fS |
–1 dB | 0.108 × fS |
–3 dB | 0.113 × fS |