Patent ID: 7518454

Claim:
A current feedback-type operational amplifier comprising multiple input parts and one output part, wherein each of said multiple input parts comprises a first input terminal, a second input terminal, and first output terminal, wherein signals input from said first input terminal are buffer amplified and output to said second input terminal, and wherein current is output to the first output terminal in an amount corresponding to current that flows to said second input terminal; said output part comprises a third input terminal and a second output terminal, wherein signals obtained by adding in terms of current the signals of all of said multiple input parts are input to said third input terminal, and wherein signals input to said third input terminal are converted to voltage signals, amplified, and output to the second output terminal as an output signal; and one of said multiple input parts is enabled and the other of said multiple input parts are disabled in response to a first external signal, wherein the impedance of said first input terminal, said second input terminal, and said first output terminal of said disabled input parts becomes high and the output current from said first output terminal becomes zero, and only the signals input to said enabled input parts are thereby amplified.