Is there any complex-valued function used to smooth signals?

To obtain a smoother signal, we usually convolve the original signal with a real-valued kernel function, such as Gaussian and Top-hat. Is there any complex-valued kernel function to smooth signals?

• Why do you want a complex kernel? Jun 25 '21 at 2:53
• can you define "smoothing"? Because, way I'd define it, it would be "low-pass filtering", and sure, there's complex low-pass filters, but since you want the whole operation to be linear phase and lower in complexity, you'd always tend towards real-valued filters. Jun 25 '21 at 7:59