An　inductorless　Cascade　SiGe　low　noise　amplifier　(LNA)　that　achieves　high　linearity　using　tunable　active　feedback　and　post-linearization　technique　is　proposed　for　ultra-wideband　(UWB)　application.　Tunable　active　feedback　composed　of　NMOS　and　parallel　resistor　is　adopted　to　improve　the　linearity　instead　of　the　resistor　feedback.　The　tunablity　of　active　feedback　can　compensate　the　gain　and　bandwidth　degradation　due　to　the　process　variation　and　parasitic　parameters.　The　post-linearization　technique　by　the　use　of　resistance-capacitance　(RC)　parallel　network　with　an　additional　diode　connected　transistor　further　improves　the　linearity.　Theoretical　analysis　is　performed　using　Volterra　series　to　obtain　an　insight　into　the　linearity　behavior　over　the　UWB　frequency　range.　The　LNA　is　implemented　using　TSMC　0.35　mu　m　SiGe　BiCMOS　technology.　Compared　with　the　conventional　Cascode　LNA,　IIP3　of　the　proposed　LNA　is　improved　by　51　dBm.　Meanwhile,　the　novel　LNA　exhibits　superior　variation　of　group　delay　1　PS,　and　achieves　the　noise　figure　of　3.8　similar　to　4.9　dB,　the　gain　of　8.8　similar　to　10.2　dB,　gain　flatness　of　+/-　0.7　dB,　good　input　and　output　impedances　matching,　and　unconditional　stablity　in　the　whole　band.　(C)　2013　Elsevier　Ltd.　All　rights　reserved.