A phase shifter circuit is an essential component in signal processing systems that shifts the phase of a signal without altering its amplitude. These circuits find applications in audio processing, frequency synthesis, phase modulation, amplitude modulation (AM), single-sideband (SSB) modulation, and more. This article delves into how an op-amp-based phase shifter circuit works, the materials required, and a step-by-step guide to building one.
What is a Phase Shifter Circuit?
A phase shifter circuit modifies the phase angle of an input signal while preserving its amplitude. One common approach to constructing this circuit is by using a resistor-capacitor (RC) lag network connected to the non-inverting terminal of an operational amplifier (op-amp). By adjusting the ratio of the input signal frequency to the RC network’s cutoff frequency, the phase shift can be controlled between 0° and 180°.
If you're interested in exploring the theory and design of phase shifters, check out this comprehensive guide on Phase Shifter Circuit with Op-Amp.
Materials Required
Operational amplifier (LM358, LM324, TL072, or similar)
Two equal resistors
One variable resistor
One capacitor
Jumper wires
Breadboard
Power supply
Circuit Diagram
Below is the circuit diagram for a basic op-amp-based RC phase shifter circuit:
How It Works
In the given circuit, two equal resistors (“R1” and “R2”) are connected to the inverting input, while the non-inverting input connects to an RC lag network (“R3” and “C1”).
Key Operating Principles
Inverting Input: The inverting configuration ensures a gain of -1 when the input signal frequency exceeds the RC lag network’s cutoff frequency.
Non-Inverting Input: The non-inverting terminal’s gain depends on the cutoff frequency, given by:
Phase Difference Calculation
The phase difference angle is related to the input frequency and the cutoff frequency :
Using the above relationship, the required resistor value for a desired phase difference can be calculated:
Try this Active Phase Shift Circuit Calculator to simplify your design process.
Step-by-Step Guide to Build the Circuit
Assemble Components: Gather all the materials listed.
Breadboard Setup: Connect the components as per the circuit diagram.
Testing and Tuning: Use a signal generator and oscilloscope to observe and fine-tune the phase shift.
For a detailed comparison of phase-related concepts, check out this insightful article on Phase Splitter vs. Phase Shifter.
Example Calculation: 90-Degree Phase Shifter
Suppose the input frequency is 1 kHz, and the desired phase difference is 90°. Let the capacitor be 0.1 μF. Using the formula:
For further details, refer to this tutorial on building a Manual Phase Shifter Switch with Op-Amp.
Applications of Phase Shifters
Phase shifters are widely used in:
Communication systems for Phase Modulation
Oscillator circuits, such as the 2N2222 Phase Shift Oscillator
Audio and signal processing
Conclusion
Phase shifter circuits are vital in numerous electronic applications. By using an op-amp and an RC lag network, you can easily create a phase shifter with adjustable phase differences. Whether you're working on communication systems or signal processing, understanding phase shifters is crucial for designing efficient circuits.
Explore more about phase shifters and related topics on our blog, including an in-depth tutorial on Op-Amp Phase Shifter Circuits.
