RF Mixing / Multiplication : Frequency Mixers and Applications

RF mixers or frequency mixers and the process of RF mixing or multiplication is key to many RF circuits enabling signals to be converted from one frequency to another as well as providing phase comparison.

RF mixer is the process of multiplication that mixes the two signals and gives only one output.
We applied two signals to a mixer and it produces a new signal at the sum and difference of the original frequencies.
It has 3 ports RF, IF, and LO.
In the RF mixer two input ports and one output port and for Up frequency conversion IF and LO is used as input port and RF are used as RF.
For Down frequency conversion RF and LO are used as input ports and IF are used as an output ports.
This mixer is a nonlinear device that is widely used to shift signals from one frequency to another.

It is a device used in up conversion and down conversion modules of RF Transceiver.
The RF mixer converts RF to lower IF frequency or to baseband to make signal processing easier in the RF receivers. This frequency translation process is known as down conversion.

The RF mixer converts a lower IF frequency or baseband frequency to a higher IF or RF frequency to provide efficient power transmission in the RF transmitter part. This frequency translation process is known as upconversion.

Why RF Mixing or Multiplication Works

Examining the precise mixing process is crucial to gain a better understanding of the RF mixing or multiplication process.
The two signals are multiplied together, as was previously indicated, and this happens as a result of a non-linear component in the circuit.
This could be a diode or an actively biased transistor or a field-effect transistor (FET).
One can think of the two signals as sine waves. The instantaneous output level is a function of the instantaneous levels of signals A and B multiplied together.
The output waveform becomes more complex as it is multiplied along the curve, as shown below.
The frequencies utilized to create the sample below are 0.75 MHz and 1.0 MHz, which are the frequencies mentioned above. The output has both a high-frequency component and a low-frequency component (the difference frequency is 0.25 MHz) (the sum frequency at 1.75 MHz).