US 5,162,679 AGranted

Sense amplifier with depletion transistor feedback

AssigneeLattice Semiconductor Corporation

InventorsJu Shen, Albert L. Chan, Chan-Chi J. Cheng

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Abstract

A sense amplifier circuit is disclosed which utilizes a field effect transistor having a negative threshold voltage to provide a faster switching speed for a given current consumption. A depletion mode transistor is utilized as the feedback transistor, with the gate of the depletion mode transistor being coupled to the output of the second stage of the sense amplifier. The first stage of the sense amplifier includes in addition to the depletion mode transistor a second field effect transistor connected in series with said feedback transistor, with the gate and drain of the second transistor being commonly connected. The sense amplifier circuit also includes third and fourth stages providing inversion and amplification of the signal provided at the output of the second stage, with the third and fourth stages comprising a depletion load inverter and a CMOS inverter, respectively.

Claims10

Dependent claims

An amplifier circuit comprising:

an input terminal (PT);
first (VCC) and second (GND) power terminals for the application therebetween of an operating potential;
a first output terminal (12);
a first field effect transistor (T11) of first conductivity type having gate, drain, and source terminals, said first field effect transistor having a negative threshold voltage;
a second field effect ransistor (T12) of first conductivity type having gate, drain, and source terminals;
means coupling said first power terminal to said drain terminal of said first field effect transistor;
means coupling in common said source terminal of said first field effect transistor (T11) to said drain terminal of said second field effect transistor (T12);
means coupling said input terminal (PT) to said gate terminal of said second field effect transistor (T12);
means coupling said input terminal (PT) to said commonly connected source terminal and drain terminal of said first (T11) and second (T12) field effect transistors respectively;
means coupling said source terminal of said second field effect transistor (T12) to said second power terminal (GND);
a third field effect transistor (T14) of first conductivity type having gate, drain and source terminals;
means coupling said source terminal of said third field effect transistor (T14) to said second power terminal (GND);
means coupling said drain terminal of said third field effect transistor (T14) to said first output terminal (12);
first circuit means coupling said first output terminal (12) to said first power terminal;
means coupling said gate terminal of said first field effect transistor (T11) to said first output terminal (12);
and
means coupling said gate of said third field effect transistor (T14) to said input terminal (PT).

14 more elements

Dependencies are inferred from the claim text.