paper reports on the design and practical development of RF co-designed low-noise amplifiers (LNAs) with multi-band RF filter and diplexer capabilities. Split-type multi-resonant stages are used as complex-terminated matching networks to functionalize new classes of multi-band filtering LNAs (MBF-LNAs) and multi-band diplexer LNAs (MBD-LNAs). In this manner, the need for conventional matching networks or additional RF filtering is eliminated in the RF front-end, thus reducing its size. Miniaturization is further enhanced using split-type multi-resonant stages that are smaller than conventional transversal resonator arrays or filter-banks of in-line coupled resonators. The MBF-LNA and the MBD-LNA concepts are validated in S-band through the realization of two dual-band MBF-LNAs (MBF-LNA I and MBF-LNA II) and a quad-band MBD-LNA. Specifically, the MBF-LNA I exhibited a low noise figure (NF) of 0.65/0.9 dB and a gain of 19.1/16.5 dB for its passbands centered at 2.5/3.29 GHz. The MBFLNA II exhibited significantly higher isolation between the two passbands of 79.5 dB while having a NF of 1/1.5 dB and gain of 18.3/15.9 dB at 2.57/3.26 GHz. The MBD-LNA demonstrated two dual-band output channels with Channel 1 having a NF of 0.92/0.93 dB and gain of 17.2/15.2 dB at 2.38/3.29 GHz and Channel 2 having a NF of 0.82/1.02 dB and gain of 16.8/14.2 dB at 2.82/3.8 GHz.