THS4304_14 Datasheet, PDF (22/33 Pages) Texas Instruments – Wideband Operational Amplifier

THS4304
SLOS436A – MARCH 2004 – REVISED JULY 2004
www.ti.com
The differential topology employed in this circuit provides for significant suppression of the 2nd-order harmonic
distortion of the amplifiers. This, along with the superior 3rd-order harmonic distortion performance of the
amplifiers, results in the SFDR performance of the circuit (at frequencies up to 40 MHz) being set by higher-order
harmonics generated by the sampling process of the ADS5500.
The amplifier circuit (with resistor divider for bias voltage generation) requires a total of 185 mW of power from a
single 5-V power supply.
+5V
RG
V _REF
RF
+5V
10 k W
10 k W
V _REF (= 2 .5V )
0.1 mF
+ 3 .3 VA +3 .3 VD
V _IN
From
50 W
source
1 :1
THS4304
V _REF
49 .9 W
+5V
THS4304
100 W 1 nF
1k W _{A IN+}
CM
ADS 5500
D
1k W _{A IN− CM}
A
100 W _{1 nF}
CM
0. 1 mF
V _REF
RG
RF
Figure 55. Differential ADC Drive Amplifier Circuit
90
Combined THS4304 and
ADS5500 SFDR
85
80
G = 10 dB,
−1 dBFS,
R_F = 249 Ω,
R_G = 115 Ω,
SNR = 69.6,
75 ^FS = ^{125 MSPS}
10
20
30
40
50
f − Frequency − MHz
Figure 56. SFDR Performance versus Frequency – THS4304 Driving ADS5500
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