This thesis replicates an ultra-low-power implantable neural front-end (TSMC 180 nm) for weak neural sensing, combining OTA amplification + VCO modulation + output buffering to support tissue transmission.Neural signals are at the tens-of-µV level but often include tens-of-mV DC offsets from electrodes; direct high-gain amplification risks saturation, while 1/f noise and strict power/area limits make low-frequency acquisition difficult.We reproduce a two-stage OTA that provides ~49 dB gain and band-pass behavior (TT about 5–150 Hz) with ~3 µV/√Hz @ 10 Hz input noise and ~329 nW OTA power, then use a current-starved VCO (TT sensitivity ~45 MHz/V at Vc=220 mV, phase noise ~−60 dBc/Hz @ 10 kHz) consuming ~609 nW.