Texas Instruments | Inverting op amp with non-inverting positive reference voltage circuit (Rev. A) | Application notes | Texas Instruments Inverting op amp with non-inverting positive reference voltage circuit (Rev. A) Application notes

Texas Instruments Inverting op amp with non-inverting positive reference voltage circuit (Rev. A) Application notes
Analog Engineer's Circuit: Amplifiers
SBOA264A – February 2018 – Revised February 2019
Inverting op amp with non-inverting positive reference
voltage circuit
Design Goals
Input
Output
Supply
ViMin
ViMax
VoMin
VoMax
Vcc
Vee
Vref
–1V
2V
0.05V
4.95V
5V
0V
1.259V
Design Description
This design uses an inverting amplifier with a non-inverting positive reference voltage to translate an input
signal of –1V to 2V to an output voltage of 0.05V to 4.95V. This circuit can be used to translate a sensor
output voltage with a positive slope and negative offset to a usable ADC input voltage range.
R1 11.1k
+
R2 6.81k
Vi
+
Vref 1.259
+
Vo
U1 TLV9001
VCC 5
Design Notes
1. Use op amp linear output operating range. Usually specified under AOL test conditions.
2. Amplifier common mode voltage is equal to the reference voltage.
3. Vref can be created with a voltage divider.
4. Input impedance of the circuit is equal to R2.
5. Choose low-value resistors to use in the feedback. It is recommended to use resistor values less than
100kΩ. Using high-value resistors can degrade the phase margin of the amplifier and introduce
additional noise in the circuit.
6. The cutoff frequency of the circuit is dependent on the gain bandwidth product (GBP) of the amplifier.
Additional filtering can be accomplished by adding a capacitor in parallel to R1. Adding a capacitor in
parallel with R1 will also improve stability of the circuit, if high-value resistors are used.
SBOA264A – February 2018 – Revised February 2019
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Inverting op amp with non-inverting positive reference voltage circuit
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Design Steps
1. Calculate the gain of the input signal.
2. Select R2 and calculate R1.
3. Calculate the reference voltage.
2
Inverting op amp with non-inverting positive reference voltage circuit
SBOA264A – February 2018 – Revised February 2019
Submit Documentation Feedback
Copyright © 2018–2019, Texas Instruments Incorporated
www.ti.com
Design Simulations
DC Simulation Results
Output Voltage (V)
T
4.95
2.5
50m
0
-1
1
2
Input voltage (V)
AC Simulation Results
T
5
0
BW = 590kHz
Gain (dB)
-5
-10
-15
-20
-25
1
10
100
1k
10k
100k
1MEG
10MEG
Frequency (Hz)
SBOA264A – February 2018 – Revised February 2019
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Inverting op amp with non-inverting positive reference voltage circuit
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Design References
See Analog Engineer's Circuit Cookbooks for TI's comprehensive circuit library.
See the circuit SPICE simulation file SBOC514.
See the Designing gain and offset in thirty seconds application report.
Design Featured Op Amp
TLV9001
Vss
1.8V to 5.5V
VinCM
Rail-to-rail
Vout
Rail-to-rail
Vos
0.4mV
Iq
60µA
Ib
5pA
UGBW
1MHz
SR
2V/µs
#Channels
1, 2, 4
www.ti.com/product/tlv9002
Design Alternate Op Amp
OPA376
Vss
2.2V to 5.5V
VinCM
Rail-to-rail
Vout
Rail-to-rail
Vos
5µV
Iq
760µA
Ib
0.2pA
UGBW
5.5MHz
SR
2V/µs
#Channels
1, 2, 4
www.ti.com/product/opa376
Revision History
4
Revision
Date
A
February 2019
Change
Downscale the title and changed title role to 'Amplifiers'.
Added links to circuit cookbook landing page and SPICE simulation file.
Inverting op amp with non-inverting positive reference voltage circuit
SBOA264A – February 2018 – Revised February 2019
Submit Documentation Feedback
Copyright © 2018–2019, Texas Instruments Incorporated
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