SBAS672E July 2014 – June 2022 ADC3221 , ADC3222 , ADC3223 , ADC3224
PRODUCTION DATA
The devices are equipped with an internal chopper front-end. Enabling the chopper function swaps the ADC noise spectrum by shifting the 1/f noise from dc to fS / 2. Figure 8-9 shows the noise spectrum with the chopper off and Figure 8-10 shows the noise spectrum with the chopper on. This function is especially useful in applications requiring good ac performance at low input frequencies or in dc-coupled applications. The chopper can be enabled via SPI register writes and is recommended for input frequencies below 30 MHz. The chopper function creates a spur at fS / 2 that must be filtered out digitally.
fS = 125 MSPS, fIN = 10 MHz |
fS = 125 MSPS, fIN = 10 MHz |