Datasheet

Data Sheet AD9278
Rev. A | Page 13 of 44
TYPICAL PERFORMANCE CHARACTERISTICS
TGC MODE
f
SAMPLE
= 40 MSPS, f
IN
= 5 MHz, R
S
= 50 Ω, LNA gain = 21.3 dB, LNA bias = mid-high, PGA gain = 24 dB, GAIN− = 0.8 V, AAF LPF
cutoff = f
SAMPLE
/3.0, HPF cutoff = LPF cutoff/12.00 (default).
1.0
0.8
0.6
0.4
0.2
0
–0.2
–0.4
–0.6
–0.8
–1.0
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
GAIN+ (V)
GAIN ERROR (dB)
09424-006
Figure 6. Gain Error vs. GAIN+
550
500
450
400
350
300
250
200
150
100
50
0
–8 –7 –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 7 8
CODES
NUMBER OF HITS (Thousands)
09424-007
1,000,000 TOTAL HITS
Figure 7. Output-Referred Noise Histogram, GAIN+ = 0.0 V
220
240
200
180
160
140
120
100
80
60
40
20
0
–8 –7 –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 7 8
CODES
NUMBER OF HITS (Thousands)
09424-008
1,000,000 TOTAL HITS
Figure 8. Output-Referred Noise Histogram, GAIN+ = 1.6 V
3.0
2.5
2.0
1.5
1.0
0.5
0
1 2 3 4 5 6 7 8 9 10
FREQUENCY (MHz)
INPUT-REFERRED NOISE (nV/ Hz)
09424-072
Figure 9. Short-Circuit, Input-Referred Noise vs. Frequency,
LNA Gain = 21.3 dB, PGA Gain = 30 dB, GAIN+ = 1.6 V
–128
–130
–132
–134
–136
–138
–140
–142
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
GAIN+ (V)
OUTPUT-REFERRED NOISE (dBFS/ Hz)
09424-009
LNA GAIN = 21.3dB
LNA GAIN = 17.9dB
LNA GAIN = 15.6dB
Figure 10. Short-Circuit, Output-Referred Noise vs. GAIN+
64
66
62
60
58
56
54
52
50
1.00.4 0.6 0.8 1.2 1.4 1.6
GAIN+ (V)
SNR (dBFS)
09424-010
Figure 11. SNR vs. GAIN+, AOUT = −1.0 dBFS