Texas Instruments THS3062EVM, Руководство пользователя, Страница: 10 / 21

Evaluation Schematic
1-2
The noninverting gain of the EVM channel 1 amplifier, when using the default
configuration, is affected by the same slight gain error plus the gain error im-
posed by the inverting input termination resistor, R2. The following equation
shows the gain for this situation:
V
O
V
I
+
ǒ
1
)
R6
R1
)
R2
Ǔ
ǒ
R4
ø
50
W
R4
ø
50
W )
R5
Ǔ
+
0.908
(2)
EVM Channel 2:
The default configuration for EVM channel 2 provides for a voltage gain of +1.
This voltage gain is the ratio of the voltage at the output pin of the amplifier (pin
7) to the voltage at the input at J5. For optimum frequency response and stabil-
ity at a gain of +1 the feedback resistor, R7, of 750
Ω
was chosen.
The noninverting gain of the EVM channel 2 amplifier, when using the default
configuration, is affected by the same slight gain error caused by R12 as
shown in Equation 1 and indicated in the following equation:
V
O
V
I
+
ǒ
*
R12
ø
50
W
R12
ø
50
W )
R11
Ǔ
+ *
0.475
(3)
THS3062 dual high-speed operational amplifier EVM features include:
-
Wide operating supply voltage range: dual supply
±
5 Vdc to dual supply
±
15 Vdc operation (see the device data sheet). Single supply operation is
obtained by connecting both J6 (GND) and J7 (VS-) to ground.
-
Convenient GND test point (TP1).
-
Power supply ripple rejection provided by inductors FB1 and FB2 followed
by tantalum capacitors C5 and C6.
-
Decoupling capacitors, C7and C8, populated with 0.1
µ
F and capacitors,
C9 and C10, populated with 100 pF—design final decoupling in accor-
dance with SLOA069.
-
Nominal 50-
Ω
input impedance for each of the configured inputs, V1in-,
V1in+ and V2in+. Termination can be configured according to the applica-
tion requirement.
-
A good example of high-speed amplifier PCB design and layout. Also see
High-Speed Amplifier PCB Layout Tips, SLOA102
.
-
50-
Ω
series matching resistors (R5 and R11).
-
953-
Ω
resistor to ground provide minimum load through 1 k
Ω
on each
amplifier.
-
PowerPAD heatsinking capability.