Differential output driver
First Claim
1. A method for operating a driver circuit, the method comprising:
- generating a first common mode voltage and a second common mode voltage;
selecting the first common mode voltage or the second common mode voltage, depending on an operating state of the driver circuit, wherein said selecting comprises selecting the first common mode voltage when the driver circuit is enabled and selecting the second common mode voltage when the driver circuit is disabled;
comparing the selected common mode voltage to a reference voltage; and
supplying a feedback signal to the driver circuit based on a difference detected in the comparison step.
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Accused Products
Abstract
A driver circuit is provided herein. In general, the driver circuit includes a driver portion, a common mode feedback portion and a current replication portion. The feedback portion receives a common mode voltage (vcm) from the driver portion and an alternative common mode voltage (vcm_alt) from the current replication portion. The feedback portion selects one of the common mode voltages for comparison with a reference voltage and generates a feedback bias signal (vcmfb) based on a voltage difference there between. When the driver circuit is enabled, the actual common mode voltage (vcm) is used to maintain the output common mode voltage around the reference voltage. When the driver circuit is disabled, the alternative common mode voltage (vcm_alt) is used to keep the bias signal (vcmfb) from drifting away.
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Citations
21 Claims
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1. A method for operating a driver circuit, the method comprising:
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generating a first common mode voltage and a second common mode voltage; selecting the first common mode voltage or the second common mode voltage, depending on an operating state of the driver circuit, wherein said selecting comprises selecting the first common mode voltage when the driver circuit is enabled and selecting the second common mode voltage when the driver circuit is disabled; comparing the selected common mode voltage to a reference voltage; and supplying a feedback signal to the driver circuit based on a difference detected in the comparison step. - View Dependent Claims (2, 3)
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4. A driver circuit, comprising:
a feedback portion configured to receive a first common mode voltage from a driver portion and a second common mode voltage from a replication portion of the driver circuit, wherein the feedback portion comprises; a selection circuit configured to select;
(i) the first common mode voltage when the driver portion is enabled, and (ii) the second common mode voltage when the driver portion is disabled; anda comparator configured to compare the selected common mode voltage to a reference voltage and to supply a feedback signal to the driver portion based on a difference detected there between. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A system, comprising:
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at least one system component configured for generating a pair of differential signals; a transmitter configured to modulate the differential signals before the modulated signals are driven across a transmission path to a receiver, wherein the transmitter comprises; a driver portion configured to modulate the differential signals and to generate a first common mode voltage of the modulated signals; a replication portion configured to generate a second common mode voltage; a selection portion configured to select the first common mode voltage or second common mode voltage; and a feedback portion configured to compare the selected common mode voltage to a reference voltage and to supply a feedback signal to the driver portion based on a difference detected there between. - View Dependent Claims (18, 19, 20, 21)
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Specification