ADC-207
7-Bit, 20MHz, CMOS Flash A/D Converters
120
110
100
90
80
OUTPUT
CODES
70
60
50
40
30
20
10
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
120
110
100
90
80
OUTPUT
CODES
70
60
50
40
30
20
10
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
NUMBER OF SAMPLES(X10
3
)
NUMBER OF SAMPLES(X10
3
)
Figure 5. Beat Frequency Test at 20MHz
Figure 6. 10MHz Envelope Test
FFT TEST
This test actually produces an amplitude versus frequency graph (Figure 7) which indicates harmonic distortion and signal-to-noise ratio. The theoretical
rms signal-to-noise ration for a 7-bit converter is +43.8dB.
70
70
65
65
60
60
55
55
50
50
45
SAMPLE PULSE = 25ns
SAMPLE PULSE WIDTH = 25ns
69.2
69.2
4MHz FUNDAMENTAL
4MHz FUNDAMENTAL
AMPLITUDE (dB)
40
35
30
30
25
25
20
20
15
15
10
10
5
0
0
–5
–5
–10
–10
27.3
27.3
0
0
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
10
10
FREQUENCY (MHz)
Figure 7. FFT Test Using the ADC-207
www.murata-ps.com
Technical enquiries
email: sales@murata-ps.com, tel:
+1 508 339 3000
MDA_ADC-207.B01
Page 5 of 6
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