Patent ID: 8107644
Filing Date: 2012-01-31
Classification: H03F

Abstract:
1. An amplifying element to be connected to an electret condenser microphone, comprising: a semiconductor substrate of a first general conductivity type; a semiconductor layer of the first general conductivity type formed on the semiconductor substrate; a junction field effect transistor formed on the semiconductor substrate and comprising a back gate diffusion region of a second general conductivity type formed in the semiconductor layer, a back gate contact region of the second general conductivity type formed in the back gate diffusion region, a channel region of the first general conductivity type formed in the back gate diffusion region, a source region and a drain region of the first general conductivity type that are formed in the channel region, and a top gate region of the second general conductivity type formed in the channel region; and a bipolar transistor formed on the semiconductor substrate, using the semiconductor substrate and the semiconductor layer as a collector region and comprising a base region of the second general conductivity type formed in the semiconductor layer, and an emitter region of the first general conductivity type formed in the base region, wherein the source region is electrically connected to the base region, and the drain region is electrically connected to the collector region.