Hybrid H-bridge and CML driver
First Claim
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1. A hybrid circuit comprising:
- a pair of resistors coupled through a central node;
a mode control circuit configured to charge the central node to a supply voltage in a current mode logic (CML) mode of operation and to allow the central node to float in an H-bridge mode of operation;
a differential amplifier configured to compare a potential of the central node to a common-mode voltage to provide a feedback signal; and
a first PMOS transistor having its gate driven by the feedback signal, the first PMOS transistor having it source coupled to the supply voltage and a drain coupled to an upper rail for the hybrid circuit.
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Abstract
In one embodiment, a hybrid output buffer having both an H-bridge mode and a CML mode of operation includes a plurality of transistor switches arranged between an upper rail and a bottom rail. A first pair of the transistor switches couples between the upper rail and respective output nodes. A pair of resistors couples between the output nodes and a central node. During H-bridge mode, the hybrid output buffer controls a potential of the upper rail responsive to a feedback signal proportional to a difference between a potential of the central node and a common-mode voltage.
14 Citations
20 Claims
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1. A hybrid circuit comprising:
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a pair of resistors coupled through a central node; a mode control circuit configured to charge the central node to a supply voltage in a current mode logic (CML) mode of operation and to allow the central node to float in an H-bridge mode of operation; a differential amplifier configured to compare a potential of the central node to a common-mode voltage to provide a feedback signal; and a first PMOS transistor having its gate driven by the feedback signal, the first PMOS transistor having it source coupled to the supply voltage and a drain coupled to an upper rail for the hybrid circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method, comprising:
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in a hybrid output buffer, receiving a mode signal having a first state and a second state; responsive to receiving the current mode signal in the first state, charging a central node of the hybrid output buffer to a power supply potential and operating the hybrid output buffer in a current mode logic (CML) mode; responsive to receiving the current mode signal in the second state, floating a potential of central node and operating the hybrid output buffer in an H-bridge mode; and while operating in the H-bridge mode, controlling a potential of an upper rail for the hybrid output buffer in response to a feedback signal that is proportional to a difference between the potential of the central node and a common-mode voltage. - View Dependent Claims (11, 12, 13, 14)
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15. A circuit, comprising:
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a first resistor; a second resistor coupled to the first resistor through a central node; a plurality of hybrid output buffers that share the first and second resistors and the central node; and a mode control circuit configured to charge the central node to a supply voltage in a current mode logic (CML) mode of operation and to allow the central node to float in an H-bridge mode of operation. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification