TSH330 STMicroelectronics, TSH330 Datasheet - Page 17

• Manufacturer Part Number: TSH330
• Description: Low noise, very large bandwidth op-amp
• Manufacturer: STMicroelectronics

Specifications of TSH330

• Bandwidth: 1.1GHz (Gain=+2)
• Quiescent Current: 16.6 mA
• Slew Rate: 1800V/µs
• Input Noise: 1.3nV/√Hz
• Distortion: SFDR = -78dBc (10MHz, 2Vp-p)

Active Filtering
8 Active Filtering
Figure 36. Low-pass active filtering, Sallen-Key
From the resistors R
amplification configuration:
We assume the following expression as the response of the system:
The cut-off frequency is not gain-dependent and so becomes:
The damping factor is calculated by the following expression:
The higher the gain, the more sensitive the damping factor is. When the gain is higher than 1, it is
preferable to use some very stable resistor and capacitor values. In the case of R1=R2=R:
Due to a limited selection of values of capacitors in comparison with resistors, we can fix C1=C2=C, so
that:
fb
and R
IN
IN
G
we can directly calculate the gain of the filter in a classical non-inverting
R
R
1
1
=
T j
1
-- - c C 1 R 1
2
=
R
R
Vout j
-------------------
2
2
Vin j
A V
c
=
=
=
=
+
R
R
2 C 2 C 1
----------------------------------- -
2 R 2 R 1
----------------------------------- -
G
G
------------------------------------- -
C 1 R 2
C
C
g
C
C
2 C 1 C 2
2 R 1 R 2
R1R2C 1C2
=
1
1
2
2
=
–
–
---------------------------------------------
1
1
+
1
+
+
+
_
_
+
2
C 2 R 1 C 1 R 1 g
R fb
--------- -
R fb
--------- -
R fb
--------- -
R g
R g
R g
------ -
j
R
R
g
c
fb
fb
+
–
------------- -
j
c
2
2
OUT
OUT
100
100
TSH330
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