Operational transconductance amplifier (OTA) of circulating current for separating AC path from DC patch path

The invention belongs to the technical field of the design of an integrated circuit, in particular to an operational transconductance amplifier (OTA) of a circulating current for separating an AC path from a DC path. The OTA comprises input opposite pipes, a cross-coupling current mirror, a DC patch and a DC current source, wherein the cross-coupling current mirror is used for amplifying the circulating current, and the DC path is used for separating a DC signal path from an AC signal path of the circulating current. The OTA can add small signal currents generated by two differential signals with correct phase by means of cross coupling, removes the limitation of the DC and the AC to the size of the cross-coupling current mirror by introducing the additional DC path, and leads the current mirror to be capable of amplifying the circulating current at any times set by a designer. The OTA improves the transconductance thereof under the condition that the power is invariable, thereby improving the unit gain bandwidth, the gain ratio and the slew ratio under the condition that the load is invariable.