Variable transconductance circuit
AssigneePanasonic Corporation
InventorsHiroyasu Morikawa, Masamichi Katada, Marie Nishinaka
Life of this patent
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Abstract
The variable transconductance circuit includes: a voltage-current conversion circuit for outputting a current signal linear with an input voltage signal; first and second MOS transistors for converting the current signal received to a square-root compressed voltage signal; and third and fourth MOS transistors for converting the square-root compressed voltage signal to a linear current signal. A bias current at the first and second MOS transistors and a bias current at the third and fourth MOS transistors are varied to control transconductance.
Claims4
A transconductance control circuit comprising:
- a square circuit comprising a trans-linear loop circuit including vertically-connected first and second MOS transistors with a gate and drain of each transistor being connected to each other, a third MOS transistor of which gate is connected to the gate of the second MOS transistor, and a fourth MOS transistor of which gate is connected to a source of the third MOS transistor, the square circuit comprising a supply means for increasing a current flowing through each of the third and fourth MOS transistors by several times and supplying a resultant current to the first and second MOS transistors, the square circuit using a drain of the second MOS transistor as a current input, and connecting one of the third and fourth MOS transistors to a first current source while outputting a current flowing through the other third or fourth MOS transistor as a current mirror output, and
- the current mirror output serves as a bias current.
Dependencies are inferred from the claim text.