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AS1545

Data Sheet - Te r m i n o l o g y

Total Harmonic Distortion (THD)

The Total Harmonic Distortion is the ratio between the RMS value of the fundamental (input signal) to the RMS value of

the first five harmonics.

THD(dBc) = 20*log

Where:

V1 is the RMS power of the input frequency (fundamental)

V2 to V6 are the RMS values of the first five harmonics

Spurious Free Dynamic Range (SFDR)

The Spurious Free Dynamic Range defines the ratio between the RMS value of the fundamental to the RMS value of

the largest peak off all spectral components below one-half of the sampling frequency, including harmonics but

excluding DC.

Channel to Channel Isolation

The Channel to Channel Isolation (Crosstalk) defines the coupling of energy from one channel into the other channel in

the ADC. It is measured by applying a 40kHz sine wave to all unselected channels and the attenuation to a 50kHz

input sine wave is determined.

Intermodulation Distortion (IMD)

The Intermodulation Distortion measures the creations of additional spectral components that are caused by

nonlinearities when applying a two tone sine wave on the input of the ADC. IMD is the ration of the RMS power in

either the second or the third intermodulation products to the sum of both input frequencies.

2

nd

order intermodulation products (IM2): f1+f2, f2-f1

3

rd

order intermodulation products (IM3): 2*f1-f2, 2*f2-f1, 2*f1+f2, 2*f2+f1

Full Power Bandwidth / Full Linear Bandwidth

The Full Power Bandwidth defines the frequency at which the reconstructed input signal amplitude drops 3dB from the

actual amplitude of the input signal, when applying a full scale signal.

The Full Linear Bandwidth defines the frequency at which the reconstructed input signal amplitude drops 0.1dB from

the actual amplitude of the input signal, when applying a full scale signal.

V2

2

V3

2

V4

2

V5

2

V6

2

++++

V1

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