ADC32RF44IRMPT datasheet(35/134 Pages) TI1

35 / 134 page

Filter

Transition

Band

Band That Folds Back On

Top of Transition Band

Bands That Aliases On

Top of Signal Band

ADC

NCO 1,

16 Bits

NCO 2,

16 Bits

Filter

2.6 GSPS

IQ 2.6 GSPS

IQ Output

Band 1

IQ Output

Band 2

fS/2

fS/4

Band 1

Band 2

fS/16

Band 2

NCO 1

NCO 2

fS/16

Band 1

650 MSPS

ADC32RF44

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SBAS809 – FEBRUARY 2017

Product Folder Links: ADC32RF44

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A dual-band example with a divide-by-8 complex is shown in Figure 74.

Figure 74. Dual-Band Example

The decimation filter responses normalized to the ADC sampling clock are illustrated in Figure 74 to Figure 97

and can be interpreted as follows:

Each figure contains the filter pass-band, transition bands, and alias bands, as shown in Figure 75. The x-axis in

Figure 75 shows the offset frequency (after the NCO frequency shift) normalized to the ADC sampling clock

frequency.

For example, in the divide-by-4 complex, the output data rate is an fS / 4 complex with a Nyquist zone of fS / 8 or

0.125 × fS. The transition band is centered around 0.125 × fS and the alias transition band is centered at 0.375 ×

fS. The alias bands that alias on top of the wanted signal band are centered at 0.25 × fS and 0.5 × fS (and are

colored in red).

The decimation filters of the ADC32RF44 provide greater than 90-dB attenuation for the alias bands.

Figure 75. Interpretation of the Decimation Filter Plots

ADC32RF44IRMPT Datasheet(PDF) 35 Page - Texas Instruments

ADC32RF44IRMPT Datasheet(HTML) 35 Page - Texas Instruments

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