PURPOSE: To reduce power consumption without hindering the high speed operation of a decoding circuit.
CONSTITUTION: In the decoding circuit having a current changeover circuit CSO driven by an input code and a wired OR circuit connecting its output to plural decoding lines DL, an active current source AEF comprizing a current supply source Q5 connected to the respective decoding lines DL and a current control circuit Q6 controlling the current from the current supply source Q5 by the voltage corresponding to the potential of the decoding lines DL is provided. Both the current supplying terminal and the current control terminal of the active current source AEF are driven by decoding output signals the same in decoding logic as and different in voltage level from each other. Consequently, a large emitter follower current flows and a high speed response is attained hen the output potential of the decoding line is changed over and it is prevented that the active current source is driven by an excessive voltage and a large pass current does not flow to the active current source when the output potential is at a stationary potential.
HONMA NORIYUKI
NANBU HIROAKI
IDEI YOJI
OHATA KENICHI
KUSUNOKI TAKESHI
HITACHI DEVICE ENG