JP2015177514A - transmission margin determination system and transmission margin determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission margin determination system capable of checking a transmission margin in a short time.SOLUTION: In the transmission margin determination system, a driver and a receiver are connected by differential interconnections and a margin of signals transmitted between the driver and the receiver is determined. The transmission margin determination system includes: a first DC bias control part and a second DC bias control part for applying DC bias voltages to sides of the differential interconnections; a control part which performs control, such that the first DC bias control part and the second DC bias control part apply the DC bias voltages, respectively; and a received waveform propriety determination part which is connected to the control part and the receiver and determines a received waveform.

Description

  The present invention relates to a transmission margin determination system and a transmission margin determination method.

  One method for determining the quality of a digital transmission system is to measure BER (Bit Error Ratio). The BER can be obtained by counting the number of received bits and errors. The ratio of the number of error bits to the total number of bits received is BER.

  For example, in a data transfer method for connecting a computer and a peripheral device called Fiber Channel, the transmission margin is set to BER <1E− at a data transfer rate of 8.5 Gbps compared to BER <1E-12 which is the standard of Fiber Channel. In the case of securing at 13, it takes 20 minutes or more, and when the transmission margin is secured at BER <1E-14, a data transfer time of 3.3 hours or more is necessary.

  Therefore, in order to improve the quality, the length of the inspection time has been a problem.

  As a technique related to the above, Patent Document 1 discloses that when testing input / output characteristics of a differential input circuit, the difference in signal level between an inverting input signal and a non-inverting input signal is made smaller than that during normal operation. A technique for detecting a differential input circuit whose operation is unstable is disclosed.

JP 2010-187047 A

  However, Patent Document 1 has a problem that it can detect a differential input circuit whose operation is unstable, but cannot inspect a transmission margin.

  An object of the present invention is to provide a transmission margin determination system capable of performing a transmission margin inspection in a short time.

  In the present invention, in order to solve the above-described problem, a driver and a receiver are connected with a differential wiring, and a transmission margin determination system for determining a margin of a signal transmitted between the driver and the receiver is provided on each side of the differential wiring. The first DC bias control unit and the second DC bias control unit that apply a DC bias voltage to the first DC bias control unit, and the control unit that controls the DC bias voltage to be applied to the first DC bias control unit and the second DC bias control unit, respectively. And a reception waveform quality determination unit that is connected to the control unit and the receiver and determines the reception waveform.

  Further, in the present invention, in order to solve the above problem, in the transmission margin determination method of the transmission margin determination system for connecting the driver and the receiver with a differential wiring and determining the margin of the signal transmitted between the driver and the receiver, The method includes a step of applying a DC bias voltage to each side of the differential wiring section, a step of controlling to apply the DC bias voltage, and a step of determining a received waveform connected to the receiver.

  ADVANTAGE OF THE INVENTION According to this invention, the transmission margin determination system which can perform a transmission margin test | inspection in a short time can be provided.

It is a block diagram which shows the structure of the transmission margin determination system in embodiment of this invention. It is a figure which shows the transmission waveform when the DC bias control part 1 and DC bias control part 2 in embodiment of this invention give the DC bias value 101 of the same electric potential to the + side and-side of the differential wiring 9. FIG. The figure which shows the transmission waveform when the DC bias value 102 and the DC bias value 202 are given to the + side and the − side of the differential wiring 9 respectively to the DC bias control unit 1 and the DC bias control unit 2 in the embodiment of the present invention. It is. It is a flowchart which shows operation | movement of the transmission margin determination system in embodiment of this invention. It is a figure which shows the determination state of the transmission margin in embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Embodiment)
The configuration of the transmission margin determination system in this embodiment will be described with reference to FIG.

  FIG. 1 is a block diagram illustrating a configuration of a transmission margin determination system according to the present embodiment.

  In FIG. 1, the driver unit 10 includes a driver 11, while the receiver unit 20 includes a receiver 21 and a received waveform quality determination unit 22. The driver unit 10 and the receiver unit 20 are connected by a differential wiring 9 via an AC coupling capacitor 5, an AC coupling capacitor 6, an AC coupling capacitor 7, and an AC coupling capacitor 8. The signal transmitted from the driver 11 is received by the receiver 21, and the received waveform quality determination unit 22 determines the quality of the received waveform. Actually, since a plurality of pairs of differential wirings 9 are bundled to form a transmission path, the driver unit 10 and the receiver unit 20 include drivers, receivers, and received waveform pass / fail judgment units corresponding to the number of transmission paths. Is provided.

  Here, the DC bias control unit 1 is connected to the True side (+ side) of the differential wiring 9 via the inductor 4 so as not to affect the high-speed signal, and similarly, the Complement side (− DC bias control unit 2 is connected to inductor side 3 via inductor 3 so as not to affect the high-speed signal. The DC bias control unit 1 and the DC bias control unit 2 can individually apply a DC potential to the + side and the − side of the differential wiring 9.

  The control unit 30 is connected to the DC bias control unit 1, the DC bias control unit 2, and the reception waveform quality determination unit 22 and controls the entire transmission margin determination system in the present embodiment.

  The operation of this embodiment will be described with reference to FIGS.

  2 shows the transmission when the DC bias control unit 1 and the DC bias control unit 2 apply the DC bias value 101 having the same potential to the + side and the − side of the differential wiring 9 using the transmission margin judgment system of FIG. It is a figure which shows a waveform.

  In this case, since the DC bias control unit 1 and the DC bias control unit 2 give the DC bias value 101 of the same potential to the receiver 21, the reception waveform at the receiver 21 is not affected by the DC bias, and the DC bias is It is possible to obtain a reception waveform equivalent to the case where no signal is given. Note that the operation limit 300 of the receiver is illustrated as an eye mask, and it is assumed that a potential difference 301 corresponding to the transmission margin is secured.

  3 applies the DC bias value 102 and the DC bias value 202 to the + side and − side of the differential wiring 9 respectively to the DC bias control unit 1 and the DC bias control unit 2 using the transmission margin determination system of FIG. It is a figure which shows the transmission waveform in a case.

  In this case, since the DC bias control unit 1 and the DC bias control unit 2 give the DC bias value 102 and the DC bias value 202 to the + side and the − side of the differential wiring 9, respectively, the reception waveform at the receiver 21 is The potential difference between the DC bias value 102 and the DC bias value 202 is shifted. Here, when the reception waveform interrupts the operation limit 300 of the receiver, the potential difference 302 corresponding to the transmission margin disappears, and the reception waveform quality determination unit 22 determines a transmission error. The control unit 30 controls the DC bias control unit 1 and the DC bias control unit 2 so as to narrow the eye opening of the differential signal of the differential wiring 9, and grasps the correlation between the transmission margin and the potential difference.

  FIG. 4 is a flowchart showing a transmission margin inspection method controlled by the control unit 30 of FIG. Prior to the inspection, the potential difference 400 when a transmission error occurs in the received waveform quality determination unit 22 is confirmed in advance, the correlation between the transmission margin and the potential difference is ascertained (S500), and the storage unit in the control unit 30 (Not shown).

  That is, when different DC bias values 102 and 202 are applied to the DC bias control units 1 and 2 to give a potential difference and the potential difference is enlarged during transmission, a transmission error starts to occur at a certain point. The potential difference until the transmission error starts corresponds to the transmission margin. As shown in FIG. 2, the potential difference 301 corresponding to the transmission margin is determined by the difference between the amplitude of the signal voltage received by the receiver 21 and the receiver operation limit 300. In addition, a potential difference corresponding to a transmission margin to be secured is determined as a potential difference determination value (S501), and is also stored in the storage unit in the control unit 30.

  The maximum value of the potential difference until the transmission error starts is determined within a range where the transmission margin to be secured can be obtained. This potential difference is determined as a potential difference determination value.

  After the start of inspection (S502), first, a potential difference of zero is set in the DC bias controller 1 and the DC bias controller 2 (S503), and data transmission is started (S504). This state is shown in FIG. Thereafter, the potential difference determination value determined in (S501) is set in the DC bias control unit 1 and the DC bias control unit 2 (S505), and it is confirmed whether or not a transmission error occurs (S506). In other words, the DC bias values 102 and 202 are applied so that the eye opening is narrowed. When the eye opening narrows and coincides with the receiver reception limit 300, a transmission error starts to occur. This state is shown in FIG. When a transmission error is detected (NG in S506), since a plurality of pairs of differential wirings 9 are bundled to form a transmission path, it is possible to identify which path has an error among a plurality of transmission paths. This is performed (S507). In this case, it is only necessary to specify the reception waveform quality determination unit in which the error has occurred. The case of (OK in S506) is a case where no transmission error has occurred, indicating that a transmission margin is secured.

  Then, zero potential difference is set in the DC bias control unit 1 and the DC bias control unit 2 (S508), and the data transmission is terminated (S509). Then, the inspection ends (S510).

  FIG. 5 is a diagram showing the pass / fail judgment result in FIG. When a potential difference determination value 511 is set in the DC bias control unit 1 and the DC bias control unit 2 and a transmission error occurs, the transmission margin is lower than the potential difference determination value 511 and conversely a transmission error occurs. If not, the potential difference is higher than the determination value, indicating that a transmission margin is secured.

  As described above, the transmission margin determination system and the transmission margin determination method of this embodiment give a potential difference between the + side and the − side of a differential signal using a DC bias circuit, not a method of measuring an error rate. Because of this method, transmission errors can be detected quickly, and transmission margin determination time can be greatly reduced.

  The present invention is not limited to the above-described embodiment, and can be implemented with various changes and modifications without departing from the gist of the present invention.

  The present invention can be used for inspection of a printed wiring board equipped with a high-speed serial transmission circuit, inspection of a cable interface connecting apparatuses, and transmission margin evaluation of high-speed serial transmission.

DESCRIPTION OF SYMBOLS 1 DC bias control part 2 DC bias control part 3 Inductor 4 Inductor 5 AC coupling capacitor 6 AC coupling capacitor 7 AC coupling capacitor 8 AC coupling capacitor 9 Differential wiring 10 Driver part 11 Driver 20 Receiver part 21 Receiver 22 Reception Waveform pass / fail judgment unit 30 Control unit

Claims (6)

In the transmission margin determination system for determining a margin of a signal transmitted between the driver and the receiver by connecting the driver and the receiver with a differential wiring,
A first DC bias controller and a second DC bias controller that apply a DC bias voltage to each side of the differential wiring;
A control unit that controls to apply a DC bias voltage to each of the first DC bias control unit and the second DC bias control unit;
A transmission margin determination system comprising: a reception waveform quality determination unit that is connected to the control unit and the receiver and determines a reception waveform.   The control unit controls the first DC bias control unit and the second DC bias control unit to apply a DC bias voltage so that an eye opening of a differential signal of the differential wiring is narrowed. The transmission margin determination system according to claim 1, wherein:   The transmission margin determination system according to claim 1, wherein the reception waveform quality determination unit determines a transmission margin of a signal received from the receiver and transmits a determination result to the control unit. The first DC bias control unit and the second DC bias control unit are:
4. The transmission margin determination system according to claim 1, wherein a DC bias is applied to the differential wiring using an inductor. In the transmission margin judgment method of the transmission margin judgment system for connecting a driver and a receiver with a differential wiring and judging a margin of a signal transmitted between the driver and the receiver,
Applying a DC bias voltage to each side of the differential wiring portion;
Each controlling to apply a DC bias voltage;
Connected to the receiver and determining a received waveform;
A transmission margin determination method comprising:   6. The step of controlling to apply the DC bias voltage is a step of controlling to apply a DC bias voltage so that an eye opening of a differential signal of the differential wiring is narrowed. The transmission margin judgment method described.

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