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US 4,390,852 AGranted
Buffer amplifier
AssigneeTektronix, Inc.
InventorJohn L. Addis
Life of this patent
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Abstract
A buffer amplifier suitable for use as an input amplifier for an oscilloscope comprises a hybrid FET-bipolar transistor source follower input stage and a complementary emitter follower output stage. Both the input and output stages include bootstraps to eliminate thermal transient response aberrations, to increase input impedance, and to maintain standing current in the output stage. Other attributes include a very short response time for high bandwidth operation, and high linearity.
Claims5
A buffer amplifier, comprising:
- a source followr input stage comprising a field-effect transistor having a gate connectable to a signal source;
- a complementary emitter follower output stage comprising an emitter-coupled pair of transistors wherein the bases thereof are coupled to the source of said field-effect transistor;
- bias means for providing a substantially constant bias current for said emitter-coupled pair of transistors, said bias means including first means for bootstrapping the emitters of said emitter-coupled pair of transistors;
- and
- second means for bootstrapping the drain of said field-effect transistor,
- wherein both of said first and second bootstrapping means are driven by the output of said source follower input stage.
3 more elements
Dependencies are inferred from the claim text.