Introduction to TL07x OpAmp Family
The TL07x family of operational amplifiers (opamps) is a popular choice for various analog circuit applications due to their excellent performance characteristics and versatility. This family includes the TL071 (single opamp), TL072 (dual opamp), and TL074 (quad opamp) devices. These opamps are known for their low noise, wide bandwidth, and high slew rate, making them suitable for a wide range of applications, including audio signal processing, active filtering, and instrumentation.
Key Features of TL07x OpAmps
Feature  TL071  TL072  TL074 

Number of OpAmps  1  2  4 
Input Offset Voltage  3 mV (max)  3 mV (max)  3 mV (max) 
Input Bias Current  65 pA (max)  65 pA (max)  65 pA (max) 
GainBandwidth Product  3 MHz  3 MHz  3 MHz 
Slew Rate  13 V/μs  13 V/μs  13 V/μs 
Supply Voltage Range  ±5 V to ±18 V  ±5 V to ±18 V  ±5 V to ±18 V 
These opamps feature a JFET input stage, which provides high input impedance and low input bias current, making them suitable for applications with highimpedance sources or long signal paths.
Basic OpAmp Configurations
Inverting Amplifier
The inverting amplifier configuration is one of the most common opamp circuits. It amplifies the input signal with a gain determined by the ratio of the feedback resistor (Rf) to the input resistor (Rin). The output signal is inverted with respect to the input.
The gain of the inverting amplifier is given by:
Gain = Rf / Rin
NonInverting Amplifier
The noninverting amplifier configuration amplifies the input signal without inverting its polarity. The gain is determined by the ratio of the feedback resistor (Rf) to the resistor connected between the inverting input and ground (Rin).
The gain of the noninverting amplifier is given by:
Gain = 1 + (Rf / Rin)
Voltage Follower (Buffer)
The voltage follower, also known as a buffer, is a special case of the noninverting amplifier with a gain of 1. It is used to isolate a highimpedance source from a lowimpedance load, preventing loading effects and maintaining signal integrity.
Active Filters
TL07x opamps are wellsuited for active filter applications due to their wide bandwidth and low noise characteristics. Active filters are used to shape the frequency response of a signal, allowing certain frequencies to pass while attenuating others.
LowPass Filter
A lowpass filter attenuates highfrequency components of a signal while allowing lowfrequency components to pass through. The cutoff frequency (fc) is determined by the values of the resistor (R) and capacitor (C) in the circuit.
The cutoff frequency is given by:
fc = 1 / (2πRC)
HighPass Filter
A highpass filter attenuates lowfrequency components of a signal while allowing highfrequency components to pass through. The cutoff frequency (fc) is determined by the values of the resistor (R) and capacitor (C) in the circuit.
The cutoff frequency is given by:
fc = 1 / (2πRC)
BandPass Filter
A bandpass filter allows a specific range of frequencies to pass through while attenuating frequencies outside this range. It can be constructed by cascading a lowpass filter and a highpass filter, with the highpass filter’s cutoff frequency (fH) higher than the lowpass filter’s cutoff frequency (fL).
The center frequency (f0) and bandwidth (BW) of the bandpass filter are given by:
f0 = √(fL × fH)
BW = fH  fL
Instrumentation Amplifier
An instrumentation amplifier is a type of differential amplifier that amplifies the difference between two input signals while rejecting commonmode noise. It is commonly used in precision measurement applications, such as strain gauges, thermocouples, and medical instrumentation.
A basic instrumentation amplifier can be constructed using three TL07x opamps, as shown in the following schematic:
The gain of the instrumentation amplifier is given by:
Gain = (1 + 2R1 / RG) × (R3 / R2)
Where R1, R2, and R3 are fixed resistors, and RG is a variable resistor used to adjust the gain.
Oscillators
TL07x opamps can be used to create various types of oscillators, which generate periodic waveforms at a specific frequency. Oscillators are used in applications such as signal generation, clock generation, and audio synthesis.
Wien Bridge Oscillator
The Wien bridge oscillator is a type of sine wave oscillator that uses a frequencyselective feedback network consisting of resistors and capacitors. The oscillation frequency is determined by the values of the resistors (R) and capacitors (C) in the feedback network.
The oscillation frequency is given by:
f = 1 / (2πRC)
Astable Multivibrator
An astable multivibrator, also known as a freerunning multivibrator, is an oscillator that generates a square wave output. It uses two TL07x opamps connected in a positive feedback configuration, with the output of each opamp connected to the input of the other through a resistorcapacitor (RC) network.
The oscillation frequency is given by:
f = 1 / (2ln(2)RC)
Comparators
TL07x opamps can be used as comparators, which are circuits that compare two input voltages and produce a digital output based on their relative levels. Comparators are used in applications such as level detection, threshold detection, and analogtodigital conversion.
When using a TL07x opamp as a comparator, the noninverting input is typically connected to a reference voltage, while the inverting input is connected to the signal to be compared. The output of the comparator will be high (positive supply voltage) when the signal voltage is greater than the reference voltage, and low (negative supply voltage) when the signal voltage is less than the reference voltage.
Conclusion
The TL07x family of opamps is a versatile and widelyused set of devices in analog circuit design. Their excellent performance characteristics, including low noise, wide bandwidth, and high slew rate, make them suitable for a wide range of applications, such as amplification, active filtering, instrumentation, and signal generation.
By understanding the basic opamp configurations and their applications, designers can effectively utilize TL07x opamps to create highperformance analog circuits for various purposes.
Frequently Asked Questions (FAQ)
 What is the difference between TL071, TL072, and TL074 opamps?

The main difference between these opamps is the number of opamp circuits contained within each package. TL071 is a single opamp, TL072 is a dual opamp (two opamps in one package), and TL074 is a quad opamp (four opamps in one package).

Can TL07x opamps be used with singlesupply voltages?

Yes, TL07x opamps can be used with singlesupply voltages, provided that the input and output voltages are kept within the supply voltage range. However, for best performance, it is recommended to use dualsupply voltages (positive and negative) to allow for a wider input and output voltage swing.

What is the maximum supply voltage for TL07x opamps?

The maximum supply voltage for TL07x opamps is ±18 V. Exceeding this voltage can damage the device.

How can I reduce noise in my TL07x opamp circuit?

To reduce noise in your TL07x opamp circuit, consider the following tips:
 Use a clean and stable power supply with sufficient Decoupling capacitors.
 Keep signal paths as short as possible and away from noise sources.
 Use shielded cables for sensitive signals.
 Use appropriate grounding techniques, such as a star ground or ground plane.
 Add filtering capacitors at the opamp inputs and outputs to reduce highfrequency noise.

Can I replace a TL07x opamp with another type of opamp in my circuit?
 In many cases, you can replace a TL07x opamp with another opamp that has similar specifications, such as input offset voltage, input bias current, gainbandwidth product, and slew rate. However, it is essential to carefully review the datasheet of the replacement opamp to ensure that it is compatible with your circuit requirements and operating conditions.