VCA8500_0803 Datasheet, PDF (17/40 Pages) Texas Instruments – 8-Channel, Ultralow-Power, Variable Gain Amplifier with Low-Noise Pre-Amp

VCA8500
www.ti.com
SBOS390A – JANUARY 2008 – REVISED MARCH 2008
TYPICAL CHARACTERISTICS (continued)
All specifications at T_A = +25°C, AVDD2 = 5.0V, AVDD1 = DVDD = 3.3V; single-ended, ac-coupled (1µF) input configuration
to the preamp (LNA), f_IN = 5MHz, V_CNTL = 1.0V, clamp disabled (CL = 1), LPF = 15MHz, and R_LOAD = 1kΩ on each output to
ground, unless otherwise noted.
NOISE FIGURE vs FREQUENCY OVER R_S
3.5
3.0
R_S = 50W
2.5
2.0
R_S = 400W
1.5
R_S = 1kW
1.0
0.5 PGA = 30dB
R_S = 200W
V_CNTRL = 1.2V
0
1
10
20
Frequency (MHz)
Figure 26.
INPUT-REFERRED NOISE vs FREQUENCY
1.30
1.28 CW Output
1.26
1.24
1.22
1.20
1.18
1.16
1.14
1.12
1.10
1.08
1.06
1.04
1.02
1.00
0.1
1.0
10 20
Frequency (MHz)
Figure 28.
2ND HARMONIC vs FREQUENCY
-45 _{VOUT = 1VPP}
-50 ^{VCNTRL = 1.2V}
30dB
-55
27dB
-60
-65
25dB ^20dB
-70
-75
1
10
Frequency (MHz)
Figure 30.
INPUT-REFERRED NOISE
1.00
R_S = 0W
0.95
V_CNTRL = 1.2V
2MHz
0.90
5MHz
0.85
0.80
0.75
0.70
20dB
25dB
27dB
Gain Setting (PGA)
Figure 27.
30dB
MAGNITUDE AND PHASE vs FREQUENCY
12k
100
80
10k
60
8k
40
20
6k
0
4k
Magnitude (Z_IN)
2k
-20
Phase
-40
-60
-80
0
100k
1M
10M
Frequency (Hz)
-100
100M
Figure 29.
3RD HARMONIC vs FREQUENCY
-45 _{VOUT = 1VPP}
-50 ^{VCNTRL = 1.2V}
-55
30dB
-60
27dB
-65
25dB
-70
20dB
-75
1
10
Frequency (MHz)
Figure 31.
Copyright © 2008, Texas Instruments Incorporated
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