Abstract: A lateral bipolar transistor is described, including a semiconductor substrate, a gate structure on the substrate, an emitter and a collector of a first conductivity type in the substrate, and a base of a second conductivity type in the substrate. The gate structure has a structure enclosing one or more closed areas. The emitter and the collector respectively includes a plurality of electrically connected unit emitters and a plurality of electrically connected unit collectors defined by the gate structure, which are arranged laterally intermixing with each other and separated by the substrate under the gate structure. The base includes a part under the gate structure.