Back to results
US 6,617,925 B2Granted
Method and apparatus for gain compensation and control in low voltage differential signaling applications
AssigneeNurlogic Design, Inc.
InventorChinh L. Hoang
Life of this patent
Estimating the term…
Abstract
A low voltage differential signaling receiver includes a gain compensation and control circuit having a low common mode compensation circuit and a high common mode compensation circuit. A control circuit is coupled to both compensation circuits and senses the operation of one to control the operation of the other. The operation of the compensation circuits ensures that differential signals having a wide range of common mode input voltages are accurately detected by the receiver. The control circuit serves to keep the combined operation of the compensation circuits stable over the wide range of common mode input voltages.
Claims19
A differential signaling apparatus, comprising:
- a pair of input nodes that receive a differential signal having an input common mode voltage;
- a pair of output nodes;
- a first compensation circuit coupled to the input nodes and the output nodes, the first compensation circuit being operative to establish a first component of a differential voltage across the pair of output nodes in response to the received differential signal;
- a second compensation circuit coupled to the input nodes and the output nodes, the second compensation circuit being operative to establish a second component of the differential voltage across the pair of output nodes in response to the received differential signal;
- and
- a control circuit that senses an operational characteristic of the first compensation circuit and controls operation of the second compensation circuit in accordance with the sensed operational characteristic,
- wherein the first compensation circuit is more operative at a first level of the input common mode voltage than at a second level of the input common mode voltage,
- and wherein the second compensation circuit is more operative at the second level of the input common mode voltage than at the first level of the input common mode voltage.
5 more elements
A differential signaling apparatus, comprising:
- a pair of input nodes that receive a differential signal having an input common mode voltage;
- a pair of output nodes;
- a first compensation circuit coupled to the input nodes and the output nodes, the first compensation circuit being operative to establish a first component of a differential voltage across the pair of output nodes in response to the received differential signal;
- a second compensation circuit coupled to the input nodes and the output nodes, the second compensation circuit being operative to establish a second component of the differential voltage across the pair of output nodes in response to the received differential signal;
- and
- a control circuit coupled to the first and second compensation circuits;
- wherein the first compensation circuit is more operative at a first level of the input common mode voltage than at a second level of the input common mode voltage,
- and wherein the second compensation circuit is more operative at the second level of the input common mode voltage than at the first level of the input common mode voltage,
- and wherein the control circuits adjusts the operation of the second compensation circuit at the first and second levels of the input common mode voltage in correspondence with the operation of the first compensation circuit so that a combined operation of the first and second compensation circuits is substantially the same at the first and second levels of the input common mode voltage.
6 more elements
A differential signaling apparatus, comprising:
- means for receiving a differential signal having an input common mode voltage;
- output means;
- first means for compensating for a low level of the input common mode voltage, the first means establishing a first component of a differential voltage at the output means in response to the received differential signal;
- second means for compensating for a high level of the input common mode voltage, the second means for establishing a second component of the differential voltage at the output means in response to the received differential signal;
- means for sensing an operational characteristic of the first means;
- and
- means for controlling operation of the second means in accordance with the sensed operational characteristic,
- wherein the first means is more operative at the low level of the input common mode voltage than at the high level of the input common mode voltage,
- and wherein the second means is more operative at the high level of the input common mode voltage than at the low level of the input common mode voltage.
6 more elements
A differential signaling method, comprising:
- receiving a differential signal having an input common mode voltage;
- firstly compensating for a low level of the input common mode voltage, the firstly compensating step including establishing a first component of a differential voltage in response to the received differential signal in accordance with a first operational characteristic;
- secondly compensating for a high level of the input common mode voltage, the secondly compensating step including establishing a second component of the differential voltage in response to the received differential signal in accordance with a second operational characteristic;
- sensing the first operational characteristic;
- and
- controlling the second operational characteristic in accordance with the sensed first operational characteristic,
- wherein the first operational characteristic is stronger at the low level of the input common mode voltage than at the high level of the input common mode voltage,
- and wherein the second operational characteristic is stronger at the high level of the input common mode voltage than at the low level of the input common mode voltage.
5 more elements
Dependencies are inferred from the claim text.