CS5101A CS5102A
0
-10
0
-10
S/(N+D): 91.06 dB
S/D: 100.5 dB
S/(N+D): 91.71 dB
S/D: 101.6 dB
-20
-20
-30
-30
T
A
= 138 °C
Signal Level
Reletive To
Full Scale
(dB)
-40
-40
Signal Level
Relative to
Full Scale
(dB)
-50
-50
-60
-60
-70
-70
-80
-80
-90
-90
-100
-110
-120
-130
-100
-110
-120
-130
dc
50
dc
50
Input Frequency (kHz)
Input Frequency (kHz)
Figure 17. CS5101A FFT (SSC Mode, 1-Channel)
Figure 18. CS5101A FFT (SSC Mode, 1-Channel)
0
0
-10
-10
-20
S/N+D: 92.01 dB
S/(N+D): 92.00dB
S/D: 101.6 dB
S/(N+D): 92.01 dB
S/D: 101.8 dB
-20
S/D: 101.8 dB
-30
-30
T
A
= 138 °C
-40
-50
-40
Signal Level
Reletive To
Full Scale
(dB)
Signal Level
Relative to
Full Scale
(dB)
-50
-60
-60
-70
-70
-80
-80
-90
-90
-100
-110
-120
-130
-100
-110
-120
-130
dc
10
dc
10
Input Frequency (kHz)
Input Frequency (kHz)
Figure 19. CS5102A FFT (SSC Mode, 1-Channel)
Figure 20. CS5102A FFT (SSC Mode, 1-Channel)
puts are often considered individual, static snap-
shots in time with no uncertainty or noise. In
reality, the result of each conversion depends on
the analog input level and the instantaneous value
of noise sources in the ADC. If sequential sam-
ples from the ADC are treated as a "waveform",
simple filtering can be implemented in software
to improve noise performance with minimal proc-
essing overhead.
at high signal frequencies due to nonlinearities in
the internal MOS switches. Dynamic signals
cause ac current to flow through the switches
connecting the capacitor array to the analog input
pin in the track mode. Nonlinear on-resistance in
the switches causes a nonlinear voltage drop.
This effect worsens with increased signal fre-
quency and slew rate. This distortion is negligible
at signal levels below -10 dB of full-scale.
All analog circuitry in the CS5101A and
CS5102A is wideband in order to achieve fast
conversions and high throughput. Wideband
noise in the CS5101A and CS5102A integrates to
35 µV rms in unipolar mode (70 µV rms in bipo-
lar mode). This is approximately 1/2 LSB rms
with a 4.5V reference in both modes. Figure 21
Noise
An A/D converter’s noise can be described like
that of any other analog component. However,
the converter’s output is in digital form so any
filtering of its noise must be performed in the
digital domain. Digitized samples of analog in-
DS45F2
27
CIRRUS [ CIRRUS LOGIC ]
