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EP0282702A2
Expired / Lapsed
EP
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Bifet logic circuit
Assignee: International Business Machines Corp
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Filing: 1988-01-26
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Granted: —
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Expires: 2008-01-26
Abstract
Abstract A BIFET logic circuit for quickly switching an output line from a high level to a reference level. The BICMOS circuit comprises a push-pull circuit including a first bipolar transistor for driving current into an output line, and a second bipolar transistor for sinking current from the output line; a CFET logic circuit for performing a logic function and including at least one N type FET for providing current to the base of the second bipolar transistor when a set of input lines to the CFET circuit has a first set of predetermined values; and a resistive means for connecting one of the source or drain of the at least one NFET to a power supply to provide a source of base current to the second bipolar transistor, even when the output line drops in voltage. This circuit is especially advantageous for driving low threshold CFET circuits. In a preferred embodiment, the circuit further includes a device for preventing a voltage differential of more than a predetermined amount between the base and emitter of the first bipolar transistor, to thereby ensure proper push-pull operation of the bipolar transistors.
Inventors
- 👤 D.C. Banker
- 👤 A.H. Dansky
- 👤 J.A. Dorler
- 👤 W.S. Klara
- 👤 F.M. Masci
- 👤 S.J. Zier
- 👤 A. Zuckerman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 11:15
CPC Classifications
H; H03; H03K; H03K19/00; H03K19/0008; H03K19/001; H03K19/02; H03K19/08; H03K19/094; H03K19/0944; H03K19/09448
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
135 words
A BIFET circuit, comprising : at least one input line and an output line; a CFET logic circuit for generating signals on a first and a second control lines in accordance with the signal values on said at least one input line; a push-pull circuit formed of bipolar transistors for driving current into said output line if said first control line is in a predetermined value range, and for sinking current from said output line if said second control line is in a predetermined value range; a power supply; and resistive means for connecting said power supply to provide current of a desired polarity through said CFET logic circuit to said second control line to thereby cause said push-pull circuit to sink current from said output line even after said output line drops in voltage.
Claim 2
Dependent Claim
135 words
A BIFET circuit, comprising : at least one input line and an output line; a CFET logic circuit for generating signals on a first and a second control lines in accordance with the signal values on said at least one input line; a push-pull circuit formed of bipolar transistors for driving current into said output line if said first control line is in a predetermined value range, and for sinking current from said output line if said second control line is in a predetermined value range; a power supply; and resistive means for connecting said power supply to provide current of a desired polarity through said CFET logic circuit to said second control line to thereby cause said push-pull circuit to sink current from said output line even after said output line drops in voltage.
Claim 3
Dependent Claim
69 words
A BIFET circuit as defined in claim 1, wherein said push-pull circuit comprises : a first bipolar transistor for driving current into said output line when conductive, and having its base connected to said first control line; a second bipolar transistor for sinking current from said output line when conductive, with its base connected to said second control line; and means for preventing said second bipolar transistor from saturating.
Claim 4
Dependent Claim
26 words
A BIFET circuit as defined in claim 2, further comprising : means for turning off said first bipolar transistor when said second bipolar transistor becomes conductive.
Claim 5
Dependent Claim
39 words
A BIFET circuit as defined in claim 3, wherein said turning off means comprises means for preventing a voltage differential of more than a predetermined amount between said first control line and the emitter of said first bipolar transistor.
Claim 6
Dependent Claim
25 words
A BIFET circuit as defined in claim 4, wherein said preventing means comprises a diode connected across said first bipolar transistor base and emitter terminals.
Claim 7
Dependent Claim
102 words
A BIFET circuit as defined in claim 1, wherein said CFET logic circuit comprises : at least one first FET of one type for generating said first control signal to have said predetermined value range when said at least one input line has a first predetermined value; and at least one FET of a different type for generating said second control signal to have said predetermined value range when said at least one input line has a second predetermined value; and wherein said resistive means is connected between said power supply and the drain or source of at least one second FET.
Claim 8
Dependent Claim
34 words
A BIFET circuit as defined in claim 6, wherein said at least one first FET and said at least one second FET are connected to said first control line and are connected in series.
Claim 9
Dependent Claim
26 words
A BIFET circuit as defined in claim 7, further comprising : means for turning off said first bipolar transistor when said second bipolar transistor becomes conductive.
Claim 10
Dependent Claim
40 words
A BIFET circuit as defined in claim 8, wherein said turning off means comprises : means for preventing a voltage differential of more than a predetermined amount between said first control line and the emitter of said first bipolar transistor.
Claim 11
Dependent Claim
25 words
A BIFET circuit as defined in claim 9, wherein said preventing means comprises a diode connected across said first bipolar transistor base and emitter terminals.
Claim 12
Dependent Claim
65 words
A BIFET circuit as defined in claim 1, wherein said CFET logic circuit comprises a feedback circuit for bringing said second control line to a value to prevent current sinking in said push-pull circuit when said first control line is in its predetermined value range; and means for preventing said feedback circuit from operating when said second control line is in its predetermined value range.
Claim 13
Dependent Claim
69 words
A BIFET circuit as defined in claim 11, wherein said push-pull circuit comprises : a first bipolar transistor for driving current into said output line when conductive, and having its base connected to said first control line; a second bipolar transistor for sinking current from said output line when conductive, with its base connected to said second control line; and means for preventing said second bipolar transistor from saturating.
Claim 14
Dependent Claim
149 words
A BIFET logic circuit, for quickly switching an output line from a high level to a level low level, comprising : at least two input lines and an output line; means for driving current into or sinking current out of said output line in accordance with the voltage values on said at least two input lines, said driving means including : a bipolar transistor operative, when conductive, to sink current from said output line; at least one N type FET for providing current to the base of said bipolar transistor when parameters of said at least two input lines have a first set of predetermined values; a power supply; and resistive means for connecting one of said source or drain of said at least one FET to said power supply to provide a source of base current to said bipolar transistor even after said output line drops in voltage.
Claim 15
Dependent Claim
149 words
A BIFET logic circuit, for quickly switching an output line from a high level to a level low level, comprising : at least two input lines and an output line; means for driving current into or sinking current out of said output line in accordance with the voltage values on said at least two input lines, said driving means including : a bipolar transistor operative, when conductive, to sink current from said output line; at least one N type FET for providing current to the base of said bipolar transistor when parameters of said at least two input lines have a first set of predetermined values; a power supply; and resistive means for connecting one of said source or drain of said at least one FET to said power supply to provide a source of base current to said bipolar transistor even after said output line drops in voltage.
Claim 16
Dependent Claim
114 words
A BIFET logic circuit as defined in claim 13, wherein said current driving and sinking means comprises : an additional bipolar transistor for driving current into said output line when conductive; a first set of at least two P type FETs for causing said additional bipolar transistor to become conductive when said at least two input lines have a first set of predetermined values; a second set of at least two N type FETs, including said at least one N type FET, for providing base current to said first mentioned bipolar transistor when said input lines have said first set of predetermined values; and means for preventing said first mentioned bipolar transistor from saturating.
References Cited (Backward Citations)
No citation records indexed.
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