IN −

IN +

NULL

NULL

OUT

2

3

4

6

7

8

1

THS4011

THS4012

SLOS216E – JUNE 1999 – REVISED APRIL 2010

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APPLICATION INFORMATION

THEORY OF OPERATION

The THS401x is a high-speed, operational amplifier configured in a voltage feedback architecture. It is built using

several GHz. This results in an exceptionally high-performance amplifier that has a wide bandwidth, high slew

rate, fast settling time, and low distortion. A simplified schematic is shown in Figure 24.

Pin numbers are for the D, DGN, and JG packages.

Figure 24. THS4011/4012 Simplified Schematic

Noise Calculations and Noise Figure (NF)

Noise can cause errors on very small signals. This is especially true when amplifying small signals. The noise

model for the THS401x is shown in Figure 25. This model includes all of the noise sources as follows:

•

•

IN+ = Noninverting current noise (pA/

√Hz)

•

IN– = Inverting current noise (pA/

√Hz)

•

12

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