US 5,684,420 AGranted

Small signal amplifier for independent p-channel and n-channel drives

AssigneeVLSI Technology, Inc.

InventorClive Roland Taylor

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Abstract

A CMOS small-signal amplifier is arranged to drive separately but in synchronism the transistors of an output stage comprising a first output transistor of a first conductivity type and a second output transistor of a second conductivity type. Each of these output transistors is driven by a respective intermediate stage comprising a current source transistor and a driver transistor directly coupled to an input terminal and a control node of the respective output transistor. The current source transistors are biassed such that the said output transistors have a symmetrical duty cycle. There may be a single bias line connected to a current source transistor in one intermediate stage and a system of current mirrors coupling the bias line to the current source transistor in the other intermediate stage.

Claims7

Dependent claims

A CMOS amplifier comprising:

(i) an input stage comprising a first current source transistor of a first conductivity type and a first drive transistor of a second conductivity type;
(ii) an input terminal connected to a control node of said driver transistor;
(iii) means providing a control bias for said first current source;
(iv) an output stage comprising a first output transistor of said first conductivity type and a second output transistor of said second conductivity type;
(v) a first intermediate stage having a second current source transistor and a second driver transistor, means connecting a control node of said second driver transistor to said input terminal and means connecting an output node of said second driver transistor to a control node of said second output transistor;
(vi) a second intermediate stage comprising a third current source transistor and a third driver transistor, means connecting a control node of said third current driver transistor to said input terminal and means connecting an output node of said third driver transistor to a control node of said first output transistor;
and
(vii) means for providing control bias for said second and third current source transistor to set respective equilibrium voltages for the control nodes of said first and second output transistors.

5 more elements

Dependencies are inferred from the claim text.