Datasheet
Noninverting Video Gain Stage
3-3
THS4221 and THS4225 EVM Applications
3.2 Noninverting Video Gain Stage
For a noninverting video gain stage, the EVM can be modified by replacing R1
with a 0 Ω resistor. A 75-Ω termination resistor is used in location R3 as shown
in Figure 3−2. Equation 2 indicates the voltage gain from J2 to J4 when
connected to a 75-Ω measurement instrument.
VOUT
IN )
+
ǒ
1 )
R4
R2
Ǔ
ǒ
Rt
Rt ) R5
Ǔ
+ 1
Figure 3−2. Noninverting Video Gain Stage
R4
1.3 kΩ
R5
75 Ω
R1
0 Ω
R3
75 Ω
R2
1.3 kΩ
+VS
−V S
−
+
U1
THS4221
4
3
1
6
2
J4
VOUT
J2
IN+
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.
(2)