Title :
Digitally programmable accurate current sources for logarithmic control of the amplification or attenuation in a gain cell
Author :
Wolffenbuttel, Reinoud F.
Author_Institution :
Dept. of Electr. Eng., Delft Univ. of Technol., Netherlands
fDate :
6/1/1988 12:00:00 AM
Abstract :
A method for realizing current sources driving a current equal to a programmable fraction of a reference current is discussed. The multiplication factor is determined by the digitally programmable power of a selected radix that is set by the ratio between the areas of two emitters. The number of identical current sources can be expanded a virtually unlimited amount without loss of accuracy or an increase in complexity. Several applications are possible; here, however, the focus is on applying this technique to digitally programmable logarithmic amplifiers or attenuators. A radix of 1.122 allows a gain cell to be programmed in decibel steps
Keywords :
analogue-digital conversion; bipolar integrated circuits; constant current sources; electric current control; gain control; linear integrated circuits; operational amplifiers; amplification control; applications; areas of two emitters; attenuation control; digitally programmable logarithmic amplifiers; digitally programmable power; gain cell; identical current sources; logarithmic control; multiplication factor; operation; programmable accurate current sources; programmable fraction; programmed in decibel steps; radix; reference current fraction control; Attenuation; Attenuators; Circuits; Data acquisition; Feedback loop; Frequency; Instruments; Resistors; Transducers; Voltage;
Journal_Title :
Solid-State Circuits, IEEE Journal of
