Logarithmic function generating system
AssigneeNippon Soken, Inc.
InventorsRitsu Katsuoka, Hisasi Kawai, Seiji Morino
Life of this patent
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Abstract
A logarithmic function generating system which generates an output signal bearing a logarithmic functional relation to the input signal. The time constant RC of a resistance-capacitance circuit is increased for every unit time elapsed in proportion to the unit time to produce a broken line approximating the logarithmic function. With its simple circuit construction employing no elements whose characteristics vary with ambient temperature changes or which tend to involve variations in characteristics among the elements of the same type, the system is capable of generating the desired logarithmic function output with a high degree of accuracy.
Claims6
A logarithmic function generating system comprising:
- a time constant setting circuit for counting clock signals having a predetermined frequency to generate a setting signal varying at every passing of a unit time;
- and
- a time constant circuit connected to said time constant setting circuit and including a capacitor, said capacitor being charged with a time constant which is constant during said unit time and is proportionally increased at said every successive unit time, whereby the voltage across said capacitor gives a broken line approximation to a logarithmic function with time as a variable.
A logarithmic function generating system comprising:
- a counter for counting clock signals having a predetermined frequency to generate a setting signal at every passing of a unit time, said setting signal consisting of a plurality of bits;
- a set of resistors supplied with a predetermined voltage at one end thereof and connected to said counter for varying the total resistance value thereof in proportion to said setting signal;
- and
- a capacitor connected to the other end of said set of resistors to be charged with a time constant which is constant during each unit time and is proportionally increased at each successive said unit time, whereby a logarithmic function with time as a variable is generated by a voltage developed across said capacitor.
Dependencies are inferred from the claim text.