TDA7590_09 Datasheet, PDF (15/42 Pages) STMicroelectronics – Digital signal processing IC for speech and audio applications

TDA7590
Key parameters
3.1.1
Table 4. Key parameters (continued)
Symbol
Parameter
DR
Dynamic range
ICL
Interchannel isolation
DAC differential
Vpp
Maximum input range at ADC1
THD/S Total harmonics distortion to signal
(THD+N)/S (THD + Noise) to signal
DR
Dynamic range
ICL
Interchannel Isolation
Min. Typ. Max. Unit
89
dB
-100
dB
2.8
V
-58
dB
-57
dB
90
dB
-85
dB
CODEC (ADC/DAC) test description
Reported typical values (table 3. - ADC and DAC sections) have been measured at Lab level
during product evaluation phase. General definitions and procedures are separately defined
in following dedicated paragraphs.
Total harmonic distortion with noise to signal (THD+N)/S
THD+N is defined as the ratio of the total power of the second power and higher harmonic
with noise components to the power of the fundamental for that signal. For THD+N
measurement, choose the DSP analyzer in digital analyzer with THD ratio as measurement
option. Measure the THD+N value at -3 dB amplitude of the input signal. First measure the
THD+N value at 1Vrms which is 0 dB reference and then measure the value at -3 dB
reference.
Dynamic range (DR)
DR is defined as the level of THD+N measured when the input sine wave amplitude is so
small that no harmonics apart from the fundamental tone are present in the output signal.
This way THD+N becomes practically the ratio between the whole signal and noise floor,
being a different way to express SNR. As a convention, at which no harmonics should be
present in the output signal, it is fixed at -40dB of the full scale amplitude.
Crosstalk or interchannel isolation
A disturbance, caused by electromagnetic interference, along a circuit or a cable pair. An
electric signal disrupts another signal in an adjacent circuit and can cause it to become
confused and cross over each other. Crosstalk is measured by applying a signal -3dB
amplitude of input signal at one channel (A) and no signal at an other channel (B),
measuring the effect on this channel (B) because of the channel (A).
Total harmonic distortion to signal (THD)/S
THD is defined as the ratio of the sum of only those components of the output signal which
are harmonic of system input, after having removed the fundamental tone corresponding to
the pure sine wave as input and the input signal.This measurement is done by using the
Harmonic analyzer which can isolate up to 15th harmonic components on the acquired
signal and report the sum of all of them, centering the fundamental tone on the frequency
provided by the input signal generator. These measurements are performed at -3dB
reference amplitude of input signal.
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