Datasheet

Noninverting Video Gain Stage
3-2
3.2 Noninverting Video Gain Stage
For a noninverting stage in EVM channel 2, the gain error imposed by R9 can
be eliminated by replacing R9 with a 0-Ω resistor. Rt is the termination resistor
of 75 Ω, as shown in Figure 3–2. As in the inverting gain stage example above,
R12 has been removed. The following equation indicates the voltage gain from
J5 to J6 when connected to a 75-Ω measurement instrument.
V
O
V
I
+
ǒ
1 )
R7
R8
Ǔǒ
Rt
Rt ) R11
Ǔ
+ 1
(2)
Figure 3–2. Noninverting Video Gain Stage
R9
0
R11
R10
–
+
U1
THS4226
8
7
9
10
4
Vs–
R7
J6
Vs+
R8
J5
V2In+
1.3 kΩ
75 Ω
1.3 kΩ
75 Ω
V2out
PD2
6
This is a common amplifier configuration used to drive transmission lines. The
75-Ω resistor in series with the output is for connection to a video instrument
or circuit.
3.3 Applications for EVM Channel 2
Since the board layout of EVM Channel 1 is identical to EVM Channel 2, the
applications above can be applied identically. The only physical difference is
the component values installed in the default configuration for the different
EVM channels. In addition, the components are labeled differently for each
EVM channel. Refer to the complete schematic and board silkscreen to locate
and resolve the differences.