JPH0244937A - Circuit for adjusting identified phase - Google Patents

Abstract

PURPOSE:To prevent the increase in a code error rate by providing a phase control section varying the phase adjustment state of a timing signal in the optimum direction according to the detection output of the code error rate so as to keep the phase adjustment state in the optimum state at all times in response to the phase characteristic change of each section. CONSTITUTION:The phase control section 7 is provided between a code error rate count section 6 and a phase adjustment section 4. Then the count output of the count section 6 is used as a detection output of the code error rate, the control section 7 varies the phase shift of the adjustment section 4 accordingly so as to control the phase adjustment state of the timing signal by the section 4 in the optimum direction. Thus, even if the phase characteristic of each section is fluctuated due to the change with the lapse of time or the like, the phase adjustment state of the timing signal is always maintained as the optimum state automatically. Thus, the code error rate is kept lowest.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a circuit that automatically adjusts the identification phase of an optical reception signal in an optical signal reception circuit.

[Conventional technology]

FIG. 2 shows a block diagram of a conventional example. After the optical reception signal applied to the input IN is equalized and amplified by the equalization amplification section 1, the identification and regeneration section 2 performs sampling etc. At the same time, the timing extractor 3 extracts a timing signal from the optical reception signal via the equalization amplifier 1, and the phase adjuster 4 performs fixed phase adjustment. Based on this phase-adjusted timing signal, the identification time point in the identification reproducing section 2 is determined.

Further, the code error detection unit 5 detects a code error in the output of the identification/reproduction unit 2, and this detection output is counted by the code error rate counting unit 6, so that the code error rate is a constant value. If the situation exceeds the above, an alarm will be displayed.

Note that the phase shift amount of the phase adjustment section 4 is determined at the time of manufacturing.
The value is adjusted and fixed to the value that minimizes the code error rate.

[Problem to be solved by the invention]

However, even if the phase adjustment status of the timing signal is initially optimal, it changes from optimal to unsuitable as each part changes over time, especially when the transmission speed is IGb/m.
In the case of high-speed optical receiving circuits exceeding υ, the phase adjustment situation becomes significantly inappropriate, resulting in the drawback that the code error rate of the received output increases.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention is constructed by the following means.

That is, in the above-mentioned circuit, a circuit for detecting the code error rate from the identification output of the optical reception signal and a phase control section for varying the phase adjustment status of the timing signal in the optimum direction according to the detection output of this circuit are provided. It is something that

[Effect]

Therefore, the phase adjustment status of the timing signal is always optimal, and the code error rate can be maintained at the lowest level regardless of changes in each part over time.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to the block diagram of FIG. 1 showing an embodiment.

This figure has almost the same configuration as that in FIG. is used as the code error rate detection output, and the control unit 7 uses ! ili!
The amount of phasing shift of the adjustment section 4 is varied, and the phase adjustment status of the timing signal by the adjustment section 4 is always controlled in the optimum direction.

That is, in the phase adjustment section 4, the amount of phase shift of the phase shift circuit is varied using, for example, a varicap, and the phase control section 7 controls the bias voltage of the varicap, thereby controlling the timing signal. In addition to determining the amount of phase shift, the control unit 7 converts the count output of the code error rate counting unit 6 into a DC bias voltage, and adjusts the adjustment unit 4 in a direction in which the bias voltage is balanced when the code error rate is minimized. is controlled.

Therefore, even if a feedback loop is formed through the control section 7 and the phase characteristics of each section change due to changes over time, etc., the phase adjustment status of the timing signal is always automatically maintained in an optimal state. .

〔Effect of the invention〕

As is clear from the above description, according to the present invention, by providing a phase control section that varies the phase adjustment status of the timing signal in the optimum direction according to the detection output of the code error rate, The phase adjustment status is always maintained as optimal according to changes in the phase characteristics of each part, and an increase in the bit error rate is prevented, which is particularly effective in receiving circuits for high-speed optical communications.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional example. 2... φ identification reproduction section, 3. Conflict... timing extraction section,
4... Phase adjustment section, 5... Code vA detection section,
6... code error rate counting section, 7... phase control section.

Claims (1)

[Claims] A circuit that adjusts the phase of a timing signal extracted from an optically received signal and identifies the optically received signal based on the adjusted timing signal, a circuit that detects a code error rate from the identification output of the optically received signal; An identification phase adjustment circuit comprising: a phase control section that varies the phase adjustment state in an optimal direction according to a detection output of the circuit.