Unlike RTLSDR LimeSDR has much wider receive bandwidth (30MHz-3.8GHz) and sample rate can go as high as 80MHz. It has built in Rx LPF (up to 60MHz) and 3xGFIR for additional filtering. Sometimes it is not enough! Because of very strong broadcast station with ERP in MW you will need BPF with high selectivity (low insertion loss) and high attenuation outside band.
HF part is a little different story: you can’t receive or send directly on HF frequencies before upconversion (for Rx) or downconversion (for Tx). For example: 20m band is upconverted using NCO (NCOfreq = Losc30MHz-Rx14MHz) with Rx LPF set to 40MHz (sample rate can be low as 1.536MHz).
Many people forget this LPF settings and as a final result you will have deaf receiver!
This is example how 20m band looks with BPF+GFIR set to 0.4MHz.
This image is without GFIR filtering. Notice big bump on the right side of the screen! It is from GSM signals in the 840MHz region because I don’t have enough attenuation above 30Mhz.