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US 8,189,728 B1Granted
Jitter measurement
AssigneeMarvell International Ltd.
InventorsJingfeng Liu, Hongwei Song
Life of this patent
Estimating the term…
Abstract
A specialized structure measures clock-to-data jitter in an optical memory interface by averaging the result of two second-order estimates of zero crossing using measured signal values on either side of the zero crossing. In one embodiment, a first estimate uses two sample points before the zero crossing and one sample point after while the second estimate uses one sample point before the zero crossing and sample two points after.
Claims19
A jitter measurement hardware circuit, comprising:
- a zero crossing detector to determine i) at least a first point and a second point of a signal prior to the signal crossing a critical level, and ii) at least a third point and a fourth point of the signal subsequent to the signal crossing the critical level;
- a first circuit configured to use at least the first point, the second point, and the third point to calculate a first approximate time at which the signal crosses the critical level;
- a second circuit configured to use at least the second point, the third point, and the fourth point to calculate a second approximate time at which the signal crosses the critical level;
- a third circuit configured to average the first approximate time and the second approximate time to determine a third approximate time at which the signal crosses the critical level.
1 more element
An optical disk interface comprising:
- an analog-to-digital converter (ADC) having an output;
- a finite impulse response (FIR) filter coupled to the output of the ADC;
- a detector coupled to an output of the FIR filter;
- a limit equalizer with an input coupled to the output of the ADC;
- and
- a jitter measurement hardware circuit coupled to an application specific output of the optical disk interface being one of the input of the limit equalizer or an output of the limit equalizer comprising:
- a zero crossing detector to determine i) at least a first point and a second point of a signal prior to the signal crossing a critical level, and ii) at least a third point and a fourth point of the signal subsequent to the signal crossing the critical level;
- a first circuit configured to use at least the first point, the second point, and the third point to calculate a first approximate time at which the signal crosses the critical level,
- a second circuit configured to use at least the second point, the third point, and the fourth point to calculate a second approximate time at which the signal crosses the critical level, and;
- a third circuit configured to average the first approximate time and the second approximate time to determine a third approximate time at which the signal crosses the critical level.
7 more elements
Dependencies are inferred from the claim text.