In the Passive Mixer first receiver, four mosfet, and four baseband impedance can synthesize High-Q bandpass filter. This on-chip High-Q bandpass filter can replace bulky, expensive and off-chip SAW filters. The impedance which is seen by the antenna is tuned by switch resistance of the Passive Mixer and the input impedance of the Trans-impedance amplifier (baseband impedance) to match antenna impedance. The gain of the feedback loop of the TIA controls the input impedance of the TIA. Further, M baseband impedance can be replaced by M/4 complex impedance. This complex impedance provides a wide RF range by changing the transconductance.
@article{arxiv.1903.09564,
title = {Mixer-First Receiver with wide-RF Range},
author = {Harshit Roy and Mrigank Sharad},
journal= {arXiv preprint arXiv:1903.09564},
year = {2019}
}