THS4041-Q1 Datasheet, PDF (13/23 Pages) Texas Instruments – 165-MHz C-STABLE HIGH-SPEED AMPLIFIER

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THS4041ĆQ1
165ĆMHz CĆSTABLE HIGHĆSPEED AMPLIFIER
SGLS229B − FEBRUARY 2004 − REVISED JUNE 2008
APPLICATION INFORMATION
theory of operation
The THS404x 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
f_Ts of 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 62.
(7) VCC +
IN − (2)
(6) OUT
IN + (3)
(4) VCC −
NULL (1)
NULL (8)
Figure 62. THS4041 Simplified Schematic
noise calculations and noise figure
Noise can cause errors on small signals. This is especially true when amplifying small signals, where
signal-to-noise ration (SNR) is important. The noise model for the THS404x is shown in Figure 63. This model
includes all of the noise sources as follows:
• e_n = Amplifier internal voltage noise (nV/√Hz)
• IN+ = Noninverting current noise (pA/√Hz)
• IN− = Inverting current noise (pA/√Hz)
• e_Rx = Thermal voltage noise associated with each resistor (e_Rx = 4 kTR_x )
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