tda8769hw/8 NXP Semiconductors, tda8769hw/8 Datasheet - Page 22

• Manufacturer Part Number: tda8769hw/8
• Description: 12-bit, 60/80/105 Msps Analog-to-digital Converter Adc Nyquist/high If Sampling
• Manufacturer: NXP Semiconductors

Philips Semiconductors
11.5.2.1
SINAD is the ratio of the signal power to the noise plus
distortion power, excluding the DC component, at a given
sample rate and input frequency:
11.5.2.2
ENOB is derived from SINAD and gives the theoretical
resolution an ideal ADC would require to obtain the same
SINAD measured on the actual ADC. A good
approximation is:
11.5.2.3
THD is the ratio of the power of the harmonics to the power
of the signal frequency. The equation for k
is:
where:
As usual the value of k = 6 (i.e. the calculation of THD is
done with the first 5 harmonics).
2003 Dec 09
SINAD
ENOB
THD
P
P
harmonics
signal
12-bit, 60/80/105 Msps Analog-to-Digital Converter
(ADC) Nyquist/high IF sampling
=
=
=
10log
=
a
SINAD 1.76
-------------------------------------
=
Signal-to-noise and distortion (SINAD)
Effective number of bits (ENOB)
Total harmonic distortion (THD)
1
10log
2
a
10
2
2
6.02
+
10
P
------------------------ -
–
a
harmonics
P
3
------------------------------------- -
P
signal
2
noise + distortion
+
P
...
signal
+
a
dB
k
2
dB.
1 harmonics
22
11.5.2.4
SNR is the ratio of the signal power to the noise power,
excluding the harmonics and DC component of the signal:
11.5.2.5
The SFDR specifies the available signal range as the
spectral distance between the amplitude of the
fundamental and the amplitude of the largest spurious
signal, harmonic and non-harmonic, excluding the
DC component.
11.5.2.6
Figure 16 shows the spectral analysis of a dual tone sine
wave input, at frequencies f
coherence criterion.
The 2nd and 3rd order intermodulation distortion products,
IMD2 and IMD3 respectively, are defined with a dual tone
input. IMD2 is defined as the ratio of the RMS value of
either tone to the RMS value of the second order
intermodulation product, IMD3 with the third order
intermodulation product. The IMD is given by:
SNR
SFDR
IMD
=
=
=
10log
10log
10log
Signal-to-noise ratio (SNR)
Spurious free dynamic range (SFDR)
Intermodulation distortion (IMD2 and IMD3)
10
10
10
P
-------------------- -
P
--------------- -
P
P
intermod
signal
------------------- -
max s
noise
signal
a
1
dB
t1
dB
dB
and f
t2
Objective specification
, meeting the
TDA8769