Method and circuit for perturbing removable singularities in coupled translinear loops
AssigneeTexas Instruments Incorporated
InventorRoy Alan Hastings
Life of this patent
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Abstract
A translinear network (34) has first (Q1, Q2, Q3, Q4) and second (Q4, Q3, Q5, Q6) translinear loops. A Trafton-Hastings clamp circuit (36) is connected to generate a piecewise-polynomial-continuous current IY, the value of which becomes undefined when current IX=0 due to a removable singularity in the transfer equation at this point. A current mirror (38) comprising a plurality of transistors (M1, M2, M3) is coupled to the Trafton-Hastings clamp circuit (36), and operates to add additional currents in transistors Q3 and Q5 to IX, when the Trafton-Hastings clamp transistor (Q7) conducts, so as to perturb the removable singularity in the transfer equation into the left half-plane.
Claims18
A translinear circuit implementing a piecewise-polynomial-continuous function containing a removable singularity in at least one segment thereof, comprising:
- a plurality of input transistors for receiving a respective plurality of input currents;
- and
- a circuit for providing a plurality of perturbation currents when said translinear circuit operates within said at least one segment containing a removable singularity, said circuit comprising:
- a Trafton-Hastings clamp transistor connected to provide a collector current that indicates when said input currents that are responsible for creating said removable singularity are substantially equal;
- and
- a current mirror controlled by said Trafton-Hastings clamp transistor to supply said perturbation currents to said input transistors;
- wherein said translinear circuit is configured to add said perturbation currents to those of said input currents received by said input transistors that are responsible for creating said removable singularity.
A method for operating a translinear circuit implementing a piecewise-polynomial-continuous function containing a removable singularity in at least one segment thereof, comprising:
- applying a plurality of input currents to a respective plurality of input transistors;
- generating a plurality of perturbation currents when said translinear circuit operates within said at least one segment containing a removable singularity by:
- connecting a Trafton-Hastings clamp transistor to provide a collector current that indicates when said input currents that are responsible for creating said removable singularities are substantially proportional;
- and
- providing a current mirror controlled by said Trafton-Hastings clamp transistor to supply said perturbation currents to said input transistors;
- and allowing said translinear circuit to add said perturbation currents to those of said input currents received by said input transistors that are responsible for creating said removable singularities.
A translinear circuit, comprising:
- a pair of translinear loops, including a respective plurality of bipolar input transistors each receiving a respective input current;
- a current mirror having a plurality of outputs each connecting to a respective one of said bipolar input transistors;
- and
- a Trafton-Hastings clamp transistor having a collector current coupled to control said outputs of said current mirror, said Trafton-Hastings clamp transistor being coupled to said translinear loops and operating to produce said collector current when said input currents cause said translinear circuit to operate in a segment of a piecewise-polynomial-continuous characteristic function having a removable singularity;
- wherein said outputs from said current mirror add to said input currents in said bipolar input transistors.
A translinear circuit having two translinear loops, comprising:
- a plurality of bipolar input transistors;
- a current mirror having a plurality of output currents to add to currents in said bipolar input transistors;
- a current source;
- a control transistor;
- a Trafton-Hastings clamp transistor having a base coupled to said current source and to a collector of said control transistor, a difference between a current delivered by said current source and a current consumed by said control transistor being coupled to said current mirror to be mirrored to said output currents.
A circuit comprising:
- a reference limb, a control limb, and an output limb,
- said reference limb comprising:
- a first bipolar transistor having an emitter coupled to a voltage rail,
- and a second bipolar transistor having an emitter coupled to a base of said first bipolar transistor;
- said control limb comprising:
- a third bipolar transistor having an emitter coupled to a voltage rail, and
- a fourth bipolar transistor having an emitter coupled to a base of said third bipolar transistor;
- said output limb comprising:
- a fifth bipolar transistor having an emitter coupled to a voltage rail, and a sixth bipolar transistor having an emitter coupled to a base of said fifth bipolar transistor;
- said second, fourth, and sixth bipolar transistors having bases coupled to a collector of said first bipolar transistor;
- a first constant current source coupled to said collector of said first bipolar transistor;
- a second constant current source coupled to said emitter of said second bipolar transistor;
- a third constant current source coupled to a collector of said third bipolar transistor,
- a first input coupled to said emitter of said fourth bipolar transistor;
- a second input coupled to said emitter of said sixth bipolar transistor;
- a current mirror having outputs coupled to said emitters of said fourth and sixth bipolar transistors;
- a Trafton-Hastings clamp bipolar transistor, having a base coupled to said collector of said third bipolar transistor, an emitter coupled to said collector of said first bipolar transistor, and a collector coupled to an input of said current mirror;
- and
- and a circuit output coupled to a collector of said fifth bipolar transistor.
Dependencies are inferred from the claim text.