Total Harmonic Distortion (THD)

THD is typically the ratio of the RMS sum of the first four

harmonics of the input signal to the fundamental itself.

This is expressed as:

monics.

Spurious-Free Dynamic Range (SFDR)

SFDR is the ratio expressed in decibels of the RMS

amplitude of the fundamental (maximum signal compo-

nent) to the RMS value of the next largest spurious

component, excluding DC offset.

Intermodulation Distortion (IMD)

The two-tone IMD is the ratio expressed in decibels of

either input tone to the worst 3rd-order (or higher) inter-

modulation products. The individual input tone levels

are at -6.5dB full scale and their envelope is at -0.5dB

full scale.

THD

VVVV

=×

+++

()





















20

10

2

2

3

2

4

2

5

2

log

12-Bit, 40Msps, +3.3V, Low-Power ADC

with Internal Reference

16

______________________________________________________________________________________

CLK

INP

INTERFACE

PIPELINE ADC

OUTPUT

DRIVERS

REFIN REFP CML REFN

OE

AGND

DGND

D11–D0

INN

PD

T/H

MAX1421

BANDGAP

REFERENCE

CLK

REF SYSTEM +

BIAS

Functional Diagram