Phase detetor and phase detecting method

Abstract

The present invention relates to a phase detector and utilisation of the phase detector for synchronisation of a digital signal with a clock signal. It is an object of the present invention to provide a phase detector with improved characteristics including jitter tolerance and jitter transfer. It is another object of the invention to provide a phase detector that generates an output signal that, when used as a control signal in a phase or frequency locked loop, keeps the gain of the control loop substantially invariant to the transition density of the phase detector input signals. According to the invention, these aspects are fulfilled by provision of a phase detector for detection of a phase difference between a first signal and a second signal. The phase detector comprises a first logic circuit for detection of a data transition of the first signal and a second logic circuit that generates a logic output signal of a first logic value upon detection of a data transition of the first signal if a transition of the second signal occurs before the transition of the first signal and of a second logic value if the transition of the second signal occurs after the transition of the first signal.

Description

technical field [0001] The present invention relates to phase detectors and the use of phase detectors for the synchronization of digital data signals and clock signals, for example in clock and data recovery circuits. Background technique [0002] When digital data is transmitted at high data rates, such as over optical transmission lines, it is typically necessary to synchronize the transmitted data bits with a clock signal. Typically, the clock signal is generated from the data signal received in the clock and data recovery circuit. Noise immunity is a key characteristic of clock and data recovery circuits. [0003] ITU-T has specific fluctuation parameters determined in the frequency domain. The fluctuation tolerance of a receiving device is defined as a sinusoidal peak-to-peak phase modulation that produces an optical loss of 1 dB. [0004] For example, white noise is added to the input signal when representing clock and data recovery components. By varying the sign...

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Problems solved by technology

Such processing requires prior knowledge of the bit frequency and produces an expensive and complex product

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