LMH6703_16 Datasheet, PDF (16/26 Pages) Texas Instruments – 1.2 GHz, Low Distortion Op Amp with Shutdown

LMH6703
SNOSAF2E – FEBRUARY 2005 – REVISED MAY 2016
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Typical Application (continued)
Capacitive output loading applications will benefit from the use of a series output resistor R_ISO. Figure 31 shows
the use of a series output resistor, R_ISO, to stabilize the amplifier output under capacitive loading. Capacitive
loads from 5 to 120 pF are the most critical, causing ringing, frequency response peaking and possible
oscillation. Figure 21 gives a recommended value for selecting a series output resistor for mitigating capacitive
loads. The values suggested in the charts are selected for 0.5 dB or less of peaking in the frequency response.
This produces a good compromise between settling time and bandwidth. For applications where maximum
frequency response is needed and some peaking is tolerable, the value of R_ISO can be reduced slightly from the
recommended values.
9.1.2 Video Performance
R_IN
75:
V_IN
R_G
560:
6.8 PF
C2
0.01 PF
+5V
C1
X1
+
+
--
R_OUT
75:
R_F
560:
0.01 PF
-5V
C3
6.8 PF
V_OUT
C4
Figure 32. Typical Video Application
The LMH6703 has been designed to provide excellent performance with production quality video signals in a
wide variety of formats such as HDTV and High Resolution VGA. NTSC and PAL performance is nearly flawless
with DG of 0.01% and DP of 0.02°. Best performance will be obtained with back terminated loads. The back
termination reduces reflections from the transmission line and effectively masks transmission line and other
parasitic capacitance from the amplifier output stage. Figure 32 shows a typical configuration for driving 75Ω
cable. The amplifier is configured for a gain of two compensating for the 6 dB loss due to R_OUT.
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