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Differential Structure Rejects

Coupled Noise at the Output

Differential Structure Rejects

Coupled Noise at the Input

Differential Structure Rejects

Coupled Noise at the Power Supply

GND

-

+

+

-

GND

Vs

Note: For proper operation, maintain

symmetry by setting

-

+

+

-

GND

Vs

GAIN

1

150

150

RECOMMENDED RESISTOR VALUES

V

O +

1

2

V

I

(11)

V

O +

– 1

2

V

I

(12)

THS4120

THS4121

SLOS319D – FEBRUARY 2001 – REVISED OCTOBER 2004

PRINCIPLES OF OPERATION (continued)

Figure 24. Definition of the Fully Differential Amplifier

The following schematics depict the differences between the operation of the THS412x, fully differential

amplifier, in two different modes. Fully differential amplifiers can work with differential input or can be

implemented as single in/differential out.

Figure 25. Amplifying Differential Signals

Figure 26. Single In With Differential Out

If each output is measured independently, each output is one-half of the input signal when gain is 1. The

following equations express the transfer function for each output:

The second output is equal and opposite in sign:

14

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