Patent ID: 9178419
Filing Date: 2015-11-03
Classification: G05F,G09G,H02M

Abstract:
1. A power source circuit comprising: a comparator configured to compare a first voltage and a second voltage; a digital arithmetic process circuit configured to average, integrate, and digital pulse width modulate a digital signal output from the comparator; a pulse width modulation output driver configured to amplify the digital signal output from the digital arithmetic process circuit; a smoothing circuit configured to smooth the digital signal output from the pulse width modulation output driver; and a DC-DC converter, wherein the DC-DC converter comprises a coil, a diode, and a transistor comprising an oxide semiconductor film, wherein a first wiring is electrically connected to the source electrode of the transistor, wherein a second wiring is electrically connected to the drain electrode of the transistor, wherein the gate electrode of the transistor is a same layer as the first wiring and the second wiring, wherein the oxide semiconductor film comprises a channel formation region, and wherein the oxide semiconductor film contains indium and zinc.