Datasheet

ǒ
V
CC)
Ǔ
)
ǒ
V
CC–
Ǔ
2
_
+
x1
Output Buffer
Vcm Error
Amplifier
C R
C
R
x1
Output Buffer
V
OUT+
V
OUT−
V
CC+
V
CC−
V
IN−
V
IN+
30 kΩ
30 kΩ
V
CC+
V
CC−
V
OCM
THS4130
THS4131
www.ti.com SLOS318H –MAY 2000– REVISED MAY 2011
APPLICATION INFORMATION
RESISTOR MATCHING
Resistor matching is important in fully-differential amplifiers. The balance of the output on the reference voltage
depends on matched ratios of the resistor. CMRR, PSRR, and cancellation of the second-harmonic distortion
diminish if resistor mismatch occurs. Therefore, it is recommended to use 1% tolerance resistors or better to
keep the performance optimized.
V
OCM
sets the dc level of the output signals. If no voltage is applied to the V
OCM
pin, it is set to the midrail voltage
internally defined as:
(1)
In the differential mode, the V
OCM
on the two outputs cancel each other. Therefore, the output in the differential
mode is the same as the input in the gain of 1. V
OCM
has a high bandwidth capability up to the typical operation
range of the amplifier. For the prevention of noise going through the device, use a 0.1 µF capacitor on the V
OCM
pin as a bypass capacitor. Figure 29 shows the simplified diagram of the THS413x.
Figure 29. THS413x Simplified Diagram
Copyright © 2000–2011, Texas Instruments Incorporated 13