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US 6,476,642 B1Granted
Differential current driver circuit
AssigneeAgere Systems Guardian Corp.
InventorDavid A. D. Morano
Life of this patent
Estimating the term…
Abstract
An improved differential current driver circuit of the invention provides techniques for programming a bus termination voltage and an output non-zero absolute current value of the driver circuit. This information is used by the driver circuit to closely match the internal elements of the circuit so as to produce two very stable (over temperature and IC processing) complementary output currents. The improved circuit also employs active feedback mechanisms to ensure a close match of the two complementary output currents. This may be done using a novel balanced bridge circuit in the output stage of the current generation portion of the driver circuit.
Claims43
A differential current driver circuit for use in driving signals on a bus, the differential current driver circuit comprising:
- a current generation stage, the current generation stage providing two current sources, the two current sources respectively generating a first current signal and a second current signal, the first and second current signals being substantially equal in magnitude and opposite in polarity;
- and
- a current switching stage, the current switching stage being functionally separate from and coupled to the current generation stage and switching the first and second current signals generated in the current generation stage between a first differential output state and a second differential output state in response to an input binary signal;
- wherein a voltage is provided to the current generation circuit so that the first and second current signals are generated for operation on the bus in accordance with a nominal bus termination voltage associated therewith.
1 more element
A differential current driver circuit for use in driving signals on a bus, the differential current driver circuit comprising:
- a current generation stage, the current generation stage providing two current sources, the two current sources respectively generating a first current signal and a second current signal, the first and second current signals being substantially equal in magnitude and opposite in polarity;
- and
- a current switching stage, the current switching stage being coupled to the current generation stage and switching the first and second current signals generated in the current generation stage between a first differential output state and a second differential output state in response to an input binary signal, wherein active components of the current generation stage and the current switching stage are predominantly complementary metal oxide semiconductor components;
- wherein a voltage is provided to the current generation circuit so that the first and second current signals are generated for operation on the bus in accordance with a nominal bus termination voltage associated therewith.
1 more element
A differential current driver circuit for use in driving signals on a bus, the differential current driver circuit comprising:
- a current generation stage, the current generation stage providing two current sources, the two current sources respectively generating a first current signal and a second current signal, the first and second current signals being substantially equal in magnitude and opposite in polarity, wherein the magnitudes of the first and second current signals are programmable;
- and
- a current switching stage, the current switching stage being coupled to the current generation stage and switching the first and second current signals generated in the current generation stage between a first differential output state and a second differential output state in response to an input binary signal;
- wherein a voltage is provided to the current generation circuit so that the first and second current signals are generated for operation on the bus in accordance with a nominal bus termination voltage associated therewith.
1 more element
A differential current driver circuit for use in driving signals on a backplane bus, the differential current driver circuit comprising:
- a current generation stage, the current generation stage providing two current sources, the two current sources respectively generating a first current signal and a second current signal, the first and second current signals being substantially equal in magnitude and opposite in polarity, the current generation stage having active feedback control for setting the absolute values of the first and second current signals;
- and
- a current switching stage, the current switching stage being coupled to the current generation stage and switching the first and second current signals generated in the current generation stage between a first differential output state and a second differential output state in response to an input binary signal.
A differential current driver circuit for use in driving signals on a backplane bus, the differential current driver circuit comprising:
- a current generation stage, the current generation stage providing two current sources, the two current sources respectively generating a first current signal and a second current signal, the first and second current signals being substantially equal in magnitude and opposite in polarity, the current generation stage having active feedback control, responsive to an input voltage, for ensuring that the first and second current signals are substantially optimally generated with respect to a bus termination voltage associated with the backplane bus;
- and
- a current switching stage, the current switching stage being coupled to the current generation stage and switching the first and second current signals generated in the current generation stage between a first differential output state and a second differential output state in response to an input binary signal.
A differential current driver circuit for use in driving signals on a bus, the differential current driver circuit comprising:
- a current generation stage, the current generation stage providing two current sources, the two current sources respectively generating a first current signal and a second current signal, the first and second current signals being substantially equal in magnitude and opposite in polarity;
- and
- a current switching stage, the current switching stage being substantially functionally separate from and coupled to the current generation stage and switching the first and second current signals generated in the current generation stage between a first differential output state and a second differential output state in response to an input binary signal;
- wherein the current generation stage comprises:
- a symmetrical bridge subcircuit for balanced generation of the first and second current signals;
- and
- one or more active feedback subcircuits, coupled to the symmetrical bridge subcircuit, for setting the absolute values of the first and second current signals and ensuring that the first and second current signals are substantially optimally generated with respect to a bus termination voltage associated with the bus.
4 more elements
A differential current driver circuit for use in driving signals on a bus, the differential current driver circuit comprising:
- a current generation stage, the current generation stage providing two current sources, the two current sources respectively generating a first current signal and a second current signal, the first and second current signals being substantially equal in magnitude and opposite in polarity;
- and
- a current switching stage, the current switching stage being coupled to the current generation stage and switching the first and second current signals generated in the current generation stage between a first differential output state and a second differential output state in response to an input binary signal, wherein active components of the current generation stage and the current switching stage are predominantly complementary metal oxide semiconductor components;
- wherein the current generation stage comprises:
- a symmetrical bridge subcircuit for balanced generation of the first and second current signals;
- and
- one or more active feedback subcircuits, coupled to the symmetrical bridge subcircuit, for setting the absolute values of the first and second current signals and ensuring that the first and second current signals are substantially optimally generated with respect to a bus termination voltage associated with the bus.
4 more elements
A differential current driver circuit for use in driving signals on a bus, the differential current driver circuit comprising:
- a current generation stage, the current generation stage providing two current sources, the two current sources respectively generating a first current signal and a second current signal, the first and second current signals being substantially equal in magnitude and opposite in polarity, wherein the magnitudes of the first and second current signals are programmable;
- and
- a current switching stage, the current switching stage being coupled to the current generation stage and switching the first and second current signals generated in the current generation stage between a first differential output state and a second differential output state in response to an input binary signal;
- wherein the current generation stage comprises:
- a symmetrical bridge subcircuit for balanced generation of the first and second current signals;
- and
- one or more active feedback subcircuits, coupled to the symmetrical bridge subcircuit, for setting the absolute values of the first and second current signals and ensuring that the first and second current signals are substantially optimally generated with respect to a bus termination voltage associated with the bus.
4 more elements
Dependencies are inferred from the claim text.