Possible RF Mixing for Increasing Frequency of a Pulse Train I am planning to build a low-power DC/AC inverter circuit along with MOSFETs and the full-bridge configuration. The MOSFETs are going to be controlled via two 4047s on the both side of the inverter.
According to my needs, the switching frequency should be 382 kHz. However, according to the 4047’s datasheet from Texas Instruments; in order the 4047 to work properly, the maximum output frequency is calculated as nearly 270 kHz and it is way below the targeted switching frequency.
Consequently, I’ve thought about mixing the 270 kHz rectangular pulse train with a local oscillator. According to my Fourier transform calculations, frequency of the output signal of the mixer becomes 382 kHz by using 112 kHz oscillator.
Is this solution is applicable?
It will not work. You can't increase the frequency of a pulse train by mixing it with a sinusoid. This figure shows what happens. The spectrum on top is the pulse train at 270 kHz; the spectrum below is the result of multiplying it by a sinuosid of 112 kHz. The purple lines correspond to shifting the original spectrum to the left, and the orange lines are the original spectrum shifted to the right.
As you can see, the resulting spectrum is not a rectangular pulse train.

If what you need is a 382 kHz sinusoid, you will need to bandpass filter the mixed signal. The BPF will have to be pretty narrow with a short transition band.