1. A fully integrated neural amplifier of neural signals, comprising: (a) a working electrode and a counter electrode both connected to a DC block capacitor Cin; (b) a capacitive feedback circuit for setting a gain of said neural amplifier as the ratio of said input capacitor (Cin) and a feedback capacitor (Cf); and (c) a folded-cascode (FC) amplifier with a gain booster; (d) wherein said gain booster comprises two common-source (CS) amplifiers; (e) wherein said first common-source (CS) amplifier is formed by a differential pair with diode-connected load; (f) wherein the differential outputs of said first common-source (CS) amplifier are connected to two gates of current source transistors of said folded-cascode (FC) amplifier, respectively, which are used as the second common-source (CS) amplifier; and (g) wherein said second common-source (CS) amplifier is embedded into the folded branch of said folded-cascode (FC) amplifier for the purpose of minimizing current consumption.