Apparatus and methods for adaptive receiver delay equalization
AssigneeAltera Corporation
InventorsWeiqi Ding, Wei Li, Sergey Shumarayev
Life of this patent
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Abstract
Disclosed are apparatus and methods for adaptive receiver delay equalization. One embodiment relates to a method for adaptive receiver delay equalization. Filtered positive and negative polarity signals are generated by a first variable-delay filter and a second variable-delay filter, respectively. A delay difference is determined between the filtered positive and negative polarity signals, and a skew-indication signal is generated based on the delay difference. A delay control signal is generated based on the skew-indication signal, and the delay control signal is sent to at least one of the first and second variable-delay filters. Other embodiments and features are also disclosed.
Claims21
A method for adaptive receiver delay equalization, the method comprising:
- receiving positive and negative polarity signals of a differential signal at data inputs of a first variable-delay filter and a second variable-delay filter, respectively, wherein each of the first and second variable-delay filters comprises a linear phase filter which provides a phase shift that varies linearly with frequency;
- generating filtered positive and negative polarity signals by the first variable-delay filter and the second variable-delay filter, respectively;
- determining a delay difference between the filtered positive and negative polarity signals by a skew detector;
- generating a skew-indication signal by the skew detector based on the delay difference;
- generating a delay control signal by an equalization control circuit based on the skew-indication signal;
- and
- sending the delay control signal to at least one of the first and second variable-delay filters.
An integrated circuit comprising:
- first and second variable-delay filters for receiving a differential signal and outputting a de-skewed differential signal, wherein each of the first and second variable-delay filters comprises a linear phase filter which provides a phase shift that varies linearly with frequency;
- a skew detector for detecting a delay difference between outputs of the first and second filters and generating a skew-indication signal based on the delay difference;
- an equalization control circuit for controlling delays of the variable-delay filters based on the skew-indication signal;
- and
- a receiver buffer for buffering the de-skewed differential signal.
An adaptive receiver delay equalization circuit comprising:
- a first variable-delay filter having a data input, a control input and an output, wherein the data input of the first variable-delay filter receives a positive polarity signal of a differential signal;
- a second variable-delay filter having a data input, a control input and an output, wherein the data input of the second variable-delay filter receives a negative polarity signal of the differential signal,
- a bias control circuit having bias voltage outputs which are connected to bias inputs of the first and second variable-delay filters, wherein the bias control circuit is electronically programmed with bias voltage settings corresponding to a predetermined data rate;
- a skew detector having a first input, a second input, and an output, wherein the first input of the skew detector is connected to the output of the first variable-delay filter, and the second input of the skew detector is connected to the output of the second variable-delay filter;
- and
- an equalization control circuit having an input and first and second outputs, wherein the input of the equalization control circuit is connected to the output of the skew detector, the first output of the equalization control circuit is connected to the control input of the first variable-delay filter, and the second output of the equalization control circuit is connected to the control input of the second variable-delay filter.
Dependencies are inferred from the claim text.