RHF350 STMICROELECTRONICS [STMicroelectronics], RHF350 Datasheet - Page 12

• Manufacturer Part Number: RHF350
• Description: Rad-hard 550 MHz low noise operational amplifier
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Noise measurements
4
12/23
Noise measurements
The noise model is shown in
●
●
●
Figure 26. Noise model
The thermal noise of a resistance R is:
Equation 1
where F is the specified bandwidth.
On a 1 Hz bandwidth the thermal noise is reduced to:
Equation 2
where k is the Boltzmann's constant, equal to 1,374.E(-23)J/°K. T is the temperature (°K).
The output noise eNo is calculated using the superposition theorem. However, eNo is not
the simple sum of all noise sources, but rather the square root of the sum of the square of
each noise source, as shown in
Equation 3
eNo
eN: input voltage noise of the amplifier.
iNn: negative input current noise of the amplifier.
iNp: positive input current noise of the amplifier.
=
V1
2
+
V2
2
R3
+
N3
V3
R1
2
+
V4
Figure 26
iN
iN
N1
Doc ID 15604 Rev 4
2
+
-
N2
Equation 3
+
V5
2
eN
+
.
V6
4kTR F
+
2
_
4kTR
.
R2
Output
HP3577
Input noise:
8 nV/ Hz
AM00837
RHF350