OPA376-Q1_16 Datasheet, PDF (21/34 Pages) Texas Instruments – Low-Noise, Low Quiescent Current, Precision Operational Amplifier

www.ti.com
OPA376-Q1, OPA2376-Q1, OPA4376-Q1
SBOS549A – APRIL 2011 – REVISED JANUARY 2016
Typical Application (continued)
8.2.1 Design Requirements
Use the following parameters for this design example:
• Gain = 5 V/V (inverting gain)
• Low-pass cutoff frequency = 25 kHz
• Second-order Chebyshev filter response with 3-dB gain peaking in the passband
8.2.1.1 Detailed Design Procedure
The infinite-gain multiple-feedback circuit for a low-pass network function is shown in Figure 30. Use Equation 1
to calculate the voltage transfer function.
Output _s
Input
s²
1 R₁R₃C₂C₅
s C₂ 1 R₁ 1 R₃ 1 R₄ 1 R₃R₄C₂C₅
(1)
This circuit produces a signal inversion. For this circuit, the gain at dc and the low-pass cutoff frequency are
calculated by Equation 2:
Gain ^R4
R₁
f_C
1
2S
1 R₃R₄C₂C₅
(2)
Software tools are readily available to simplify filter design. WEBENCH® Filter Designer is a simple, powerful,
and easy-to-use active filter design program. The WEBENCH Filter Designer lets you create optimized filter
designs using a selection of TI operational amplifiers and passive components from TI's vendor partners.
Available as a web-based tool from the WEBENCH® Design Center, WEBENCH® Filter Designer allows you to
design, optimize, and simulate complete multi-stage active filter solutions within minutes.
8.2.2 Application Curve
20
0
-20
-40
-60
100
1k
10k
100k
1M
Frequency (Hz)
Figure 31. Low-Pass Filter Transfer Function
9 Power Supply Recommendations
The OPAx376-Q1 family of devices is specified for operation from 2.2 V to 5.5 V (±1.1 V to ±2.75 V); many
specifications apply from –40°C to +125°C. Parameters that can exhibit significant variance with regard to
operating voltage or temperature are presented in the Typical Characteristics.
Copyright © 2011–2016, Texas Instruments Incorporated
Submit Documentation Feedback
21
Product Folder Links: OPA376-Q1 OPA2376-Q1 OPA4376-Q1