For the Microchip tinyAVR® 0- and 1-series, and megaAVR® 0-series devices to get a 10-bits resolution on the conversion result, the ADC clock frequency may be maximum 1.5 MHz. When the ADC clock is 1.5 MHz, the sampling frequency is 150 ksps, which confines the upper frequency in the sampled signal to ~75 kHz.