RF input to a mixer is 200 MHz and the local oscillator frequency is 150 MHz. What output would you expect to see at the IF output prior to any filtering?

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Multiple Choice

RF input to a mixer is 200 MHz and the local oscillator frequency is 150 MHz. What output would you expect to see at the IF output prior to any filtering?

A mixer generates new frequencies by multiplying the two signals, producing components at the sum and the difference of their frequencies. With an RF input of 200 MHz and a local oscillator of 150 MHz, you get 200 ± 150, which gives 50 MHz and 350 MHz. Real mixers aren’t perfectly isolated, so some of the LO signal can appear at the IF output (150 MHz) and some of the RF signal can leak through (200 MHz) before any filtering. Therefore, the spectrum at the IF output prior to filtering would show 50, 150, 200, and 350 MHz.

A mixer generates new frequencies by multiplying the two signals, producing components at the sum and the difference of their frequencies. With an RF input of 200 MHz and a local oscillator of 150 MHz, you get 200 ± 150, which gives 50 MHz and 350 MHz. Real mixers aren’t perfectly isolated, so some of the LO signal can appear at the IF output (150 MHz) and some of the RF signal can leak through (200 MHz) before any filtering. Therefore, the spectrum at the IF output prior to filtering would show 50, 150, 200, and 350 MHz.

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