THS4081, THS4082

175MHz LOW POWER HIGHSPEED AMPLIFIERS

SLOS274D − DECEMBER 1999 − REVISED JUNE 2001

11

POST OFFICE BOX 655303

APPLICATION INFORMATION

theory of operation

The THS408x is a high-speed, operational amplifier configured in a voltage feedback architecture. It is built

using a 30-V, dielectrically isolated, complementary bipolar process with NPN and PNP transistors possessing

slew rate, fast settling time, and low distortion. A simplified schematic is shown in Figure 38.

IN − (2)

IN + (3)

(6) OUT

(4) VCC −

(7) VCC +

Figure 38. THS4081 Simplified Schematic

noise calculations and noise figure

Noise can cause errors on very small signals. This is especially true when amplifying small signals, where

signal-to-noise ratio (SNR) is very important. The noise model for the THS408x is shown in Figure 39. This

model includes all of the noise sources as follows: