Title:
LOGARITHMIC CONVERSION CIRCUIT
Document Type and Number:
Japanese Patent JP2929945
Kind Code:
B2
Abstract:
PURPOSE: To provide a logarithmic conversion circuit with less fluctuation in logarithmic conversion characteristic due to the influence of the change of a temperature and manufacture dispersion and is suitable for making into an integrated circuit.
CONSTITUTION: The diffrential pair to which dynamic bias current technique is applied is used as an index circuit to be inserted into the feedback route of an operational amplifier 21. Current is supplied to the emitter of this differential pair which is commonly connected by the sum current of the current which is equal to the collector current of a transistor 24 and prescribed constant current 25 and the emitter is driven. Because saturation current which is large in manufacture dispersion does not appear in a parameter specifying the input/ output characteristic of this differential pair, the conversion characteristic of a logarithmic conversion circuit can be accurately made into a constant characteristic.
Inventors:
KIMURA KATSUHARU
Application Number:
JP21643394A
Publication Date:
August 03, 1999
Filing Date:
September 09, 1994
Export Citation:
Assignee:
NIPPON DENKI KK
International Classes:
H03G11/00; G06G7/24; H03G11/08; (IPC1-7): H03G11/08; G06G7/24; H03G11/00
Attorney, Agent or Firm:
Umeo Yamauchi
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