AFS090 datasheet(121/334 Pages) MICROSEMI

121 / 334 page

Fusion Family of Mixed Signal FPGAs

R e visio n 2

2 - 105

Resolution

ADC resolution is the number of bits used to represent an analog input signal. To more accurately

replicate the analog signal, resolution needs to be increased.

Sampling Rate

Sampling rate or sample frequency, specified in samples per second (sps), is the rate at which an ADC

acquires (samples) the analog input.

SNR – Signal-to-Noise Ratio

SNR is the ratio of the amplitude of the desired signal to the amplitude of the noise signals at a given

point in time. For a waveform perfectly reconstructed from digital samples, the theoretical maximum SNR

(EQ 14) is the ratio of the full-scale analog input (RMS value) to the RMS quantization error (residual

error). The ideal, theoretical minimum ADC noise is caused by quantization error only and results directly

from the ADC’s resolution (N bits):

EQ 14

SINAD – Signal-to-Noise and Distortion

SINAD is the ratio of the rms amplitude to the mean value of the root-sum-square of the all other spectral

components, including harmonics, but excluding DC. SINAD is a good indication of the overall dynamic

performance of an ADC because it includes all components which make up noise and distortion.

Total Harmonic Distortion

THD measures the distortion content of a signal, and is specified in decibels relative to the carrier (dBc).

THD is the ratio of the RMS sum of the selected harmonics of the input signal to the fundamental itself.

Only harmonics within the Nyquist limit are included in the measurement.

Figure 2-84 • Offset Error

Input Voltage to Prescaler

Ideal Output

Offset Error = 1.5 LSB

Actual Output

0...00

0...01

SNRdB[MAX]

6.02dB N 1.76dB

AFS090 Datasheet(PDF) 121 Page - Microsemi Corporation