A Basic Introduction to Frequency Multipliers

June 29, 2019

If you work with circuits and signals, you might have come across (or heard about) frequency multipliers; these devices are quite extensively used in electronics and system design.

What are frequency multipliers and what do they actually do?

Let’s try to understand.

Basics of Frequency Multipliers

Frequency multipliers are circuits that generate an output signal with output frequency is an exact integral multiple of its input frequency. Alternatively speaking, frequency multipliers “multiply” frequency of a driver source to produce a signal of higher-order harmonic frequencies.

But why do we even need to do that? Why do we need to multiply frequencies to a higher order?

Application of frequency multipliers

One common scenario where we often need to multiply lower frequencies to generate higher frequencies is when we’re designing a high-frequency telecommunication system.

Developing a high-frequency telecommunication system using a powerful crystal can be costly. So, engineers prefer building the system around a frequency multiplier. This allows them to design a high-performance system using devices that are significantly less expensive and consume less power.

This begs the question: Why not use an oscillator (or some other simpler approach) to generate a signal of desired frequency?

The answer lies in the ability of frequency multipliers to produce more stable oscillations.

Superiority of frequency multipliers

Frequency multipliers have this characteristic property, where if the input frequency changes within a certain finite range, it’s impact remains negligible on the frequency multiplication ratio of the frequency multipliers. This enables frequency multipliers to generate more stable oscillations compared to oscillators, sub-harmonic mixers, up-conversion mixers, etc.

How do frequency multipliers work?

Operation principle of frequency multipliers

We know that when a sinusoidal signal is applied to a linear circuit, the circuit reproduces the signal as a sine wave. However, if that same sinusoidal signal is applied to a non-linear circuit, the circuit introduces distortion into the signal, creating harmonics in the process. It’s this property of non-linear circuits that frequency multipliers use to produce signals with higher frequencies.

In its most basic construction, a frequency multiplier consists of a non-linear device and a bandpass filter. The non-linear device alters the frequency components of a signal and passes the signal to the bandpass filter for conditioning. The bandpass filter filters off unwanted harmonics from the distorted signal and produces desired frequencies at the output.

Buy high performance frequency multipliers at ADSANTEC

At ADSANTEC, we stock the best quality electronic and circuit components—including high performance frequency multipliers—for your specialty system design needs. View our complete product catalogue for more details.