In this paper, a set of ultra-compact CMOS bandpass filters are proposed for ultra-wideband (UWB) applications. For this aim, a comparative study was first performed enabling to deduce that Chebyshev-inverse and Hourglass filtering functions can be the most suitable for UWB operation. The impact of the latter functions on the easiness of implementation in integrated passive device (IPD) technologies and filtering performance was investigated, where the designed filters were implemented in 0.18-µm CMOS technology. Finally, the issue of in-band interference has been addressed by rejecting the wireless local area network (WLAN) signals. The performance of the proposed UWB filters were validated through post layout simulation, and good fulfilling with UWB specifications was noted while depicting a compact size, smaller than 0.6 mm², which is very miniaturised compared with relevant works mentioned in the state of the art.