Designing a FIR filter with Butterworth characteristics

I’m trying to design a FIR filter with a flat passband, but fir1() gives me a rounded passband. How do I get a flat passband more like a Butterworth filter?

Without any details, screenshots, or code, I don’t think I can help you. But you can try increasing the filter order, which will increase the spectral precision. Or try using firls. Or use a different filter like a sinc function.

Good point, I just needed to increase my filter order. I guess FIR and IIR filters have different types of tradeoff to consider.