Question T7A03
From subelement T7 - T7A
Which of the following is used to convert a signal from one frequency to another?
Why is this correct?
A mixer is specifically designed to convert signals from one frequency to another by combining two input frequencies to produce sum and difference frequencies. This frequency conversion is essential in superheterodyne receivers, where incoming RF signals are converted to intermediate frequencies (IF) for easier processing. Phase splitters divide signals into multiple phases, inverters change signal polarity, and amplifiers increase signal strength—none perform frequency conversion like mixers do.
Memory tip
Look for the word 'convert' in frequency-related questions—it almost always points to mixers. Mixers are the mathematical operators of radio circuits, creating new frequencies through combination rather than just modifying existing signals like other circuit types.
Learn more
In superheterodyne receiver architecture, mixers enable the frequency conversion that makes modern radio reception possible. They combine the incoming signal with a local oscillator frequency to produce intermediate frequencies that are easier to filter and amplify. This frequency conversion principle also applies in transmitters for upconversion and in test equipment. Understanding mixer operation helps explain why receivers can tune across wide frequency ranges while maintaining consistent performance characteristics.
Think about it
Why do you think superheterodyne receivers convert incoming signals to intermediate frequencies rather than processing them directly at their original frequency?