JPH05159595A - Electrooptical sample hold device - Google Patents

Abstract

(57) [Summary] [Structure] A light source 22 for generating an optical pulse train, an optical modulator 23 for changing the light intensity in accordance with an input electric signal to be subjected to sample and hold processing, and emitting the light intensity, and an optical intensity for the electric signal. N having a function of converting and integrating the electric signal and a reset function of resetting the integrated amount to zero at a constant cycle
And (n ≧ 2) light receivers, and k + (i− of the optical pulse train of the k-th (where 1 ≦ k ≦ N) light receiver.
1) Immediately after the arrival of the Nth pulse, (k + 1) + (i
-1) Starting in the period immediately before the arrival of the Nth pulse, (k-1) + i + k immediately after the arrival of the Nth pulse
It is characterized in that the reset timing of each of the N photodetectors is set so that the time zone ending in the period immediately before the arrival of the iN-th pulse is in the reset state. [Effect] The input waveform can be sampled in a wide band at a high speed, and N sample-and-hold output waveforms can be obtained by thinning out every Nth waveform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electro-optical sample for use in the first stage of a data capturing device for capturing an analog electrical signal waveform as data, which is in great demand in the field of digital information processing equipment including measurement equipment.
The present invention relates to a hold device.

[0002]

2. Description of the Related Art Conventionally, in an apparatus for converting an analog signal waveform into a digital amount and performing digital information processing,
A data capturing device for performing analog / digital conversion (A / D conversion) is attached to the conversion unit. In consideration of widening the band of this data acquisition device, in order to prevent the accuracy deterioration due to the change of the analog signal itself while the A / D converter performs conversion, a sample and hold is provided in the preceding stage of the A / D converter. A configuration in which the devices are arranged is adopted. This sample-and-hold device is for holding the value of the analog signal at a certain moment during the fixed time for conversion by the A / D converter. The band and accuracy of this sample and hold device will be the rule. This sample-hold device has been realized by an electronic circuit in the related art, and a capacitor (hold capacitor) is used to hold an analog amount of input. In this device, an electrical switch is used to realize a state in which this capacitance is connected to the input to capture the instantaneous value of the analog signal in the capacitance (sample mode) and a state in which this value is separated and held (hold mode). Is required. As this electrical switch, depending on the required operation speed, MOSFET switch, MES
Although FET switches, diode bridge switches, etc. are used, it is customary to use a diode bridge switch composed of a Schottky barrier diode (SBD) for applications requiring high-speed and wide-band performance.

The performance required for these switches is as follows. (1) The response speed of the switch itself is fast, and (2) The ON resistance when the switch is on is low. In the sample mode, the terminal voltage of the hold capacitor quickly follows the input analog signal. It is necessary that the time constant determined by the product of the ON resistance and the hold capacitance is sufficiently small. (3) High OFF resistance when the switch is cut off In the hold mode, the time constant determined by the product of the OFF resistance of the switch and the hold capacitance must be sufficiently large in order to reduce the leakage of charges from the hold capacitance. (4) The parasitic capacitance value between the switch terminals is sufficiently small and its nonlinearity is small. This parasitic capacitance increases the resistance of the switch at the moment when the circuit shifts from the sample mode to the hold mode, and is in series with the hold capacitance. It becomes apparent in the form of being connected, gives an error to the hold voltage, leaks the input signal in the hold mode, and its nonlinearity causes higher-order distortion, which is a factor of accuracy deterioration. (5) The parasitic capacitance value between the switch control terminal and the switch terminal is sufficiently small. This causes a clock signal applied to switch the switch control terminal to switch the switch to leak into the output terminal, which causes deterioration in accuracy.

These matters are requirements that conflict with each other when an actual switch is manufactured, and it is difficult to satisfy all of them at the same time. This situation will be described by taking a diode bridge switch as an example. The ON resistance when the switch is turned on described in the second section is mainly given by the sum of the junction resistance when the diode is forward biased and the lead electrode resistance including the contact resistance. .. In order to reduce the junction resistance at the time of forward bias, it is necessary to flow a sufficient forward bias current, and since the current density of the junction has an upper limit, a certain junction area is required. Further, it is desirable that the bonding area be large in order to reduce the resistance of the lead electrode. On the other hand, the parasitic capacitances described in the fourth and fifth terms are dominated by the junction capacitance when the diode is reverse biased and the parasitic capacitance between the lead electrodes, and in order to reduce these, the junction area is small. Is desirable. That is, the second term and the fourth and fifth terms have a trade-off relationship. At present, the fastest sample and hold device is GaAs.
1G sampling per second using a diode bridge switch of Schottky barrier diode, bandwidth 500MH
An accuracy of about 6 bits has been realized in z (Reference 1: K. Poulton, JJ Corcoran and T. Hornak, 'A1-GHz
6-bit ADC System, 'IEEE J. Solid-State Circuits, vol.
SC-22, No.6, pp.962-970, Dec.1987), although the higher speed and higher accuracy of this circuit has great demand in the field of digital information processing equipment including measurement equipment. No
Due to the above-mentioned essential problems, it is difficult to find out.

Therefore, as a solution to the above-mentioned drawbacks of the sample-hold device, an electro-optical sample-hold device as shown in FIG. 4 has been considered. As shown in FIG. 4 (A), this electro-optical sample and hold device 1 is intended to enable the sample and hold device to operate at a higher speed and in a wider band, and generates an optical pulse train. The light source 2, an optical modulator 3 that changes the light intensity emitted from the light source 2 according to an input electric signal and emits the light, and converts the incident light intensity into an electric signal and integrates the electric signal, and at the same time, integrates the electric signal. It is roughly configured from a light receiver 4 that returns the amount to zero. In addition, the light receiver 4 is
As shown in FIG. 1B, it is roughly composed of a photodiode (PD) (or avalanche photodiode (APD)) 5, a capacitor 6 and an analog switch 7.

The operating principle of the electro-optical sample and hold device 1 is as follows. First, the light source 2 generates an optical pulse train at a cycle corresponding to the sampling cycle. The optical modulator 3 intensity-modulates this optical pulse train in accordance with an electric signal which is an input to the sample and hold. The electrical signal that is input here is sampled by the optical pulse train, and its value is extracted as the intensity of the modulated optical pulse and is incident on the light receiver 4. The intensity of the light pulse incident on the light receiver 4 is converted into a current intensity by the photodiode (PD) (or avalanche photodiode (APD)) 5, and then integrated by the capacitance. After the integration of one light pulse, a fixed reset period is provided immediately before the arrival of the next light pulse, and the operation of resetting the integrated value stored by the analog switch 7 connected in parallel to the capacitor 6 to zero is repeated. As a result, the output waveform as shown in FIG. 7C is obtained, and the sample and hold processing is achieved.

A feature of the electro-optical sample and hold device 1 is that, as can be understood from the explanation of the operating principle, the portion having the sample function and the portion having the hold function are electrically separated by interposing light. It is in. The analog switch 7 used in the light receiver 4 is related only to the hold function and does not participate in the sample function. Therefore, the analog switch 7 has one sample function and one hold function.
It is performed only by an electric circuit by opening and closing, and the strict conditions required for the switch of the conventional sample and hold device in which the switch has both functions are alleviated. The sampling rate of this electro-optical sample and hold device 1,
Roughly calculating the band, for example, if the light source 2 is a semiconductor laser that is industrially prevailing as a light source for 10 Gbit / sec class optical communication, the pulse width is 20 to 3 by performing gain switching operation.
It is possible to generate an optical pulse train of about 0 ps and a repetition frequency of about several GHz. Also, regarding the optical modulator 3,
Similar to the semiconductor laser, the development is being promoted for optical communication, and one having a band exceeding 10 GHz is industrially prevailing. Considering such a situation, it is considered that the electro-optical sample and hold device can have a speed performance of several Gbits per second and a band of 10 GHz.

FIG. 5 shows the configuration (FIG. 5A) and its operation (FIG. 5A) when the photoreceiver 4 in the electro-optical sample and hold device 1 is replaced with another photoreceiver 8 having a holding function. It is a figure explaining B)). Here, first, the input optical pulse waveform is directly converted into an electric signal. After that, this electric signal is divided into two, and a delay D is given to one of the signals by a delay unit 9 for a time equal to the period (sampling period) of the optical pulse, and the signal has the opposite sign to the other signal waveform without delay. Addition is performed and the result is integrated. As a result, an output waveform as shown in FIG. 7B is obtained, and the sample and hold function is realized.

[0009]

However, in the electro-optical sample and hold device 1 described above, it is expected that the following two problems will become apparent when the speed performance and band performance are improved. The first problem is Fig. 4 (C).
As shown in FIG.
This is because every time the integrated amount stored in the capacitor 6 is reset to zero by the light receiving circuit, the output waveform returns to the reset level every time. This means that the output waveform contains a frequency component corresponding to the sampling frequency even if the input waveform to which the sample and hold process is applied has a low frequency. The operation of resetting the integrated quantity stored in the capacitor 6 to zero is indispensable for the function of this light receiving circuit. Not only is the time in the level wasted in the subsequent data processing, but it is also unsuitable as an interface for the device. That is, it is desirable that the output waveform of the sample-hold device is such that after one sample value is held for a certain period of time, the sample value immediately shifts to the next sample value without passing through the reset level. Also,
In the light receiver 8 having the hold function, since the delay device 9 is used, if the sampling frequency is changed, the delay amount of the delay device 9 must be changed accordingly. There is also a problem that the size of the delay device 9 is large.

The second problem is that the above electro-optical sample
Applying the hold device 1 as a part of the entire system,
It occurs in connection with the construction of larger systems. That is, even if only the electro-optical sample and hold device 1 can be speeded up, the system as a whole cannot function at high speed unless the operation of the device connected thereafter is speeded up. As an example, an analog-digital conversion system (A / D conversion system) used for a data input unit of a measuring instrument will be taken up and considered as an example. For example, in a data input section of a digitizing oscilloscope which is a general measuring instrument for observing and processing an analog signal waveform, an analog signal is converted into a digital quantity by an A / D conversion device, and the converted digital quantity is converted into a digital quantity. The storage is temporarily stored in the storage device. The electro-optical sample and hold device 1
Furthermore, the conversion accuracy deterioration at the high frequency input of the A / D conversion device, which is arranged in the preceding stage of the A / D conversion device, is prevented by holding the sample value at a certain moment constant during A / D conversion. There is. That is, the band of the entire A / D conversion system is widened by the electro-optical sample and hold device 1 and plays an important role of being regulated by the band of the device 1.

However, if the speed of the sample and hold device is increased, the speed of the subsequent A / D converter and the storage device cannot catch up with the situation. Currently, the fastest A / D converter has a flash type configuration and is used as an LSI by a silicon integrated circuit. The conversion speed limit at present is 1 to 2 G _sps (Reference 2: T. Wakimoto, Y. Akazawa and S. Konak).
a, 'Si Bipolar 2-GHz 6-bit Frash A / D Conversion LS
I, 'IEEE J. Solid-State Circuits, vol.SC-23, No.6, pp.1
345-1350, Dec. 1988). In addition, for storage devices, CM
Since the OS integrated circuit is used, the operation speed is further slowed down, which becomes a bottleneck in increasing the speed of the entire system. As a countermeasure against this, the output of the sample and hold device is thinned out every N samplings to be divided into N outputs.
By connecting the D converter and the storage device, the processing speed of the latter stage is reduced to 1 / N (interleaved format)
The method is adopted.

FIG. 6 shows A / A using the interleaved format.
It is a figure which shows the structure of the D conversion system 11. This A / D
In the conversion system 11, the first-stage sample and hold device 15 is operated at 1 G _sps , and this output is 250 M
Four sample and hold devices 17, which operate with _sps , ...
By inputting into, thinning division is performed, and the subsequent processing speed is reduced to 250 MHz (reference document 3: K. Poulto).
n, JJCorcoran and T.Hornak, 'A 1-GHz 6-bit ADC Sys
tem, 'IEEE J. Solid-State Circuits, vol.SC-22, No.6, p
p.962-970, Dec.1987.). However, this A / D conversion system 11 has N (four in this case) sample and hold devices in addition to the drawback that it is necessary to mount the device between the inputs of the N sample and hold devices. There is also a drawback in that it is necessary to further provide another sample and hold device in the preceding stage in order to suppress the influence of timing variation.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an electro-optical sample and hold device which can effectively solve the above problems and drawbacks.

[0014]

In order to solve the above problems, the present invention employs the following electro-optical sample and hold device. That is, the electro-optical sample and hold device according to claim 1 has a light source that generates an optical pulse train having a constant period and a constant intensity, a light input / output terminal, and an electric input terminal, and is emitted from the light source. An optical modulator that changes the intensity of a light beam according to an input electrical signal to be subjected to sample-hold processing and emits the light, and a light modulator that is emitted from the light modulator and is divided into N light beams, respectively. It is provided with N (where N ≧ 2) photodetectors having a function of converting the light intensity of a light beam into an electric signal and integrating the electric signal and a reset function of returning the integrated amount to zero at a constant cycle. , These N light receivers are k-th (however, 1
≤k≤N) k + (i-1) of the optical pulse train of the optical receiver
Immediately after the arrival of the Nth pulse, (k + 1) + (i-
1) Start in the period immediately before the arrival of the Nth pulse, and then (k-1) + i immediately after the arrival of the Nth pulse, k + i
The reset timing of each of the N optical receivers is set so that the time zone that ends immediately before the arrival of the Nth pulse is in the reset state.

The electro-optical sample according to claim 2
The electro-optical sample and hold device according to claim 1, wherein the holding device has N input terminals and one output terminal for inputting output electric signals of the optical receivers to the output side of the optical receivers. It is characterized in that an analog adder including is provided.

[0016]

In the electro-optical sample and hold device according to the first aspect of the present invention, the number of the light modulator and the light source having the sampling function is one, and only N (N ≧ 2) light receivers having the holding function are used. , The part responsible for the sample function and the part responsible for the hold function are clearly separated, and the input waveform is wideband,
Moreover, high-speed sampling is performed, and N sample-and-hold output waveforms are obtained by thinning out every Nth sample. Further, since there is only one input, it is not necessary to adjust the timing variation between analog inputs, and the sample and hold device for suppressing the influence of the timing variation is unnecessary.

The electro-optical sample according to claim 2
In the hold device, the electro-optical sample according to claim 1,
In the hold device, on the output side of the N optical receivers,
By providing an analog adder having N input terminals for inputting the output electric signals of these light receivers and one output terminal, unnecessary high frequency components included in the output waveform are eliminated, and this output waveform It is possible to obtain a waveform in which, after holding one sample value of the above for a certain period of time, the waveform immediately transitions to the next sample value without going through the reset level one by one. Therefore, unlike the conventional case, an unnecessary adjustment part such as a delay amount is not required, and an interface with another device connected to the subsequent stage of this device is facilitated. Further, the period of the reset signal for each light receiver is 1 / N of the entire sampling period, and the operation speed is improved.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1A is a schematic diagram of an electro-optical sample and hold apparatus 21 which is an embodiment of the electro-optical sample and hold apparatus according to the first aspect. This electro-optical sample and hold device 21 has a light source 22 for generating a light pulse train of a constant intensity at a constant cycle, an optical input / output terminal and an electric input terminal, and changes the intensity of an incident light beam according to an input electric signal to emit it. The optical modulator 23, and two light receivers 24 and 25 having a function of converting incident light intensity into an electric signal and integrating the electric signal and a reset function of returning the integration amount to zero at a constant cycle Has been done.

This electro-optical sample and hold device 21
Then, the light emitted from the light source 22 is incident on the optical input terminal of the optical modulator 23, and the electrical signal for applying the sample and hold processing is applied to the electrical input terminal of the optical modulator 23, and emitted from the optical modulator 23. The output light is split into two light beams, which are incident on the photodetectors 24 and 25, respectively.

As shown in FIG. 1B, the reset timing of these photodetectors 24 and 25 is 1+ (i-1) Nth (where i is an integer) of the optical pulse train in the first photodetector. Time immediately after the arrival of the second pulse immediately before the arrival of the 2+ (i-1) N-th pulse and ends immediately after the arrival of the iN-th pulse and immediately before the arrival of the 1 + iN-th pulse. The band is reset,
In the second photodetector, the 1 + iNth pulse starts in the period immediately after the arrival of the 2+ (i-1) Nth pulse and immediately before the arrival of the 3+ (i-1) Nth pulse. The time zone ending in the period immediately after the arrival of the pulse and immediately before the arrival of the 2 + iNth pulse is in the reset state.

Next, the operation principle of the electro-optical sample and hold device 21 will be described with reference to FIG.
The light receivers 24 and 25 convert the intensity of the incident light into an electric signal, and when the reset pulse opens the switch (not in the reset state), the light pulse intensity is integrated by the capacitance. However, when an optical pulse arrives while the switch is closed and in the reset state, the electric signal is not integrated and the output remains unchanged at the reset level because the capacitance is short-circuited by the switch.

In the photodetector 24, the switch is opened at the arrival of the first optical pulse, the value is integrated and held for a certain period of time, and then the switch is closed immediately before the arrival of the second optical pulse to enter the reset state. If the reset state is continued until immediately after the arrival of the second light pulse, the second light pulse does not affect the output of the light receiver 24. If the switch is opened by the time immediately before the arrival of the third light pulse, the value can be integrated and held for a certain period. If this operation is continued with the fourth light pulse and the fifth light pulse, it is possible to obtain an output waveform in which only the odd light pulses are extracted and held for a certain period.

Similarly, the photodetector 25 performs an operation in which the odd-numbered and even-numbered optical pulses in the case of the photodetector 24 are exchanged to extract only the even-numbered optical pulses and hold them for a certain period to obtain an output waveform. Obtainable.
In this way, it is possible to obtain two sample and hold outputs in which sampled values are alternately thinned. The above is the operating principle of the electro-optical sample and hold device 21.

If the above operating principle is applied to the case of N light receivers, the output light of the optical modulator 23 is divided into N light beams, and these N light beams are respectively received by N light receivers 24, 25,
It is possible to obtain N outputs decimated to 1 / N by being incident on.

This electro-optical sample and hold device 21
In the above, although the number of outputs is thinned and divided into N, the hold time for holding one sample value of each output constant cannot exceed one cycle of the entire sampling period. However, considering this in the A / D conversion system 11, the operating speed bottleneck of this system is the low-speed operation of the storage device, and the data conversion time of the A / D conversion device is the hold time of the sample hold device. If it is inside, there will be no problem.

As described above, according to the electro-optical sample and hold device 21, the part having the sampling function and the part having the holding function are clearly separated, and the input waveform is sampled in a wide band and at high speed. As a sample-and-hold device incorporated in a system that can obtain N sample-and-hold output waveforms by thinning out every N, sample analog signals at high speed and in a wide band, and process at low speed in the subsequent stage. Extremely useful.

Further, since there is only one input, it is not necessary to adjust the timing variation between analog inputs, and the sample and hold device for suppressing the influence of the timing variation is not required. Therefore, the A / D conversion system It is possible to promote economic efficiency and miniaturization in.

(Second Embodiment) FIG. 2 is a schematic block diagram of an electro-optical sample and hold apparatus 31 which is an embodiment of the electro-optical sample and hold apparatus according to the present invention. This electro-optical sample and hold device 31 is the same as the two optical receivers 2 of the electro-optical sample and hold device 21 of the first embodiment.
A two-input analog adder 32 having two input terminals for inputting the output electric signals of the photodetectors 24 and 25 and one output terminal is provided on the output sides of the input terminals 4 and 25.

This two-input analog adder 32 holds one sample value for a certain period of time, and then obtains one output so as to quickly shift to the next sample value without passing through the reset level. It is a thing.

Next, the operation principle of the electro-optical sample and hold device 31 will be described. Light receiver 24, 25
The two output waveforms output from each are input to the 2-input analog adder 32 and added. These two output waveforms will hold the sampled value of the other when one output is at the reset level, so the addition result will give the sampled value of either of the two outputs at any time. Strictly speaking, when the two output waveforms are added together, a spike-like whiskers that returns to the reset level for a moment at the moment when the sample value of one output shifts to the sample value of the other output appears, but the frequency band of the 2-input analog adder 32 By appropriately limiting the value, one output can be obtained in such a manner that one sample value is actually held for a certain period of time, and then the value immediately shifts to the next sample value without passing through the reset level.

For example, in the case of the electro-optical sample and hold device 1, a sampling frequency of 1 GHz is 1 G
Although a reset signal of Hz is required, in the electro-optical sample and hold device 31, the reset signal period of each of the photodetectors 24 and 25 is 1 of the entire sampling period.
/ 2 is enough, so that two photodetectors 24 and 25 have 5
A reverse phase reset signal of 00 MHz is added.

FIG. 3A is a schematic configuration diagram of an electro-optical sample and hold device 41 applied to an actual A / D conversion system, and FIG. 3B is a diagram showing a differential output waveform by computer circuit simulation. .. This electro-optical sample
The hold device 41 is provided with a level shift circuit 42 and an output buffer amplifier 43 in series on the output side of the 2-input analog adder 32 of the electro-optical sample and hold device 31, and the light source 22 and the optical modulator 23 are connected to each other. Omitted.

Here, it is assumed that the output light of the optical modulator 23 is split into two rays and then is incident on this circuit.
The circuit shown here can also be realized as an integrated circuit using FETs.
ET is used as a switch, and a drain and a source are switched by applying a reset signal to the gate of the FET. The 2-input analog adder 32 is configured to add the output signals of the light receiver 24 and the light receiver 25 and output the result in a differential manner.

Further, the DC component of the differential output is adjusted by the potential of the terminal A, and the adjustment can be made when there is an imbalance between the output amplitudes of the photodetectors 24 and 25 by the potentials of the terminals B and C. Functions are added. A level shift circuit 42 and an output buffer amplifier 43 are added in the subsequent stage for convenience so that the output of the 2-input analog adder 32 can be directly taken out with low resistance.

In the computer circuit simulation shown in FIG. 1B, an optical pulse train with a period of 1 GHz is intensity-modulated by the optical modulator 23 by a sine wave signal, and the output light is split into two light receivers 24 and 25. It was supposed to be incident. In addition, the reset signal opens the switch to the light receiver 24 immediately before the arrival of one optical pulse, closes the switch immediately before the arrival of the next optical pulse, and switches the switch immediately before the arrival of the next optical pulse. It is assumed that the operation such as opening is repeated, and that the light receiver 25 is operated in a phase opposite to that of the light receiver 24. Two reset signal inputs are 500MHz cycle, duty cycle 5
It is a 0% square wave differential input.

According to the result of the output waveform obtained by the computer circuit simulation, the electro-optical sample and hold device 41 holds one sample value for a certain period of time and then does not go through the reset level one by one.
It was proved that one output was obtained such that the sample value immediately moved to the next sample value.

As described above, according to the electro-optical sample and hold device 31 (41), there is no unnecessary high frequency component contained in the output waveform, and one sample value is held as the output waveform for a certain period of time. After that, it is possible to quickly obtain an output waveform that shifts to the next sample value without passing through the reset level. Therefore, it is possible to facilitate the interface with another device connected to the latter stage of this device. Furthermore, in the case of one sample and hold output, it becomes possible to obtain a hold time approximately equal to the maximum sampling period.

Further, the period of each reset signal of each of the light receivers 24 and 25 is half of the entire sampling period, which is effective for improving the operation speed. This effect is N
= 2 is particularly remarkable. In addition, the light receivers 24 and 25
The size can be reduced, and various effects such as an unnecessary adjustment portion such as a delay amount can be achieved.

[0039]

As described above in detail, according to the electro-optical sample and hold device of the first aspect of the present invention, a light source for generating a light pulse train having a constant period and a constant intensity, and an optical input. An optical modulator having an output terminal and an electric input terminal, which changes the intensity of a light beam emitted from the light source in accordance with an input electrical signal to be subjected to sample and hold processing, and emits the light, and an N modulator emitted from the optical modulator. It is provided corresponding to each light beam divided into books, and has a function of converting the light intensity of the light beam into an electric signal and integrating the electric signal, and a reset function of returning the integration amount to zero at a constant cycle. N (where N ≧ 2) optical receivers, and these N optical receivers are k + (i−1) of the optical pulse train of the k-th (where 1 ≦ k ≦ N) optical receiver. ) Immediately after the arrival of the Nth pulse ( +1) + (i-1) time that starts immediately before the arrival of the Nth pulse and ends in the period immediately after the arrival of the (k-1) + iNth pulse and immediately before the arrival of the k + iNth pulse Since the reset timing of each of the N optical receivers is set so that the band is in the reset state, the portion responsible for the sampling function and the portion responsible for the hold function are clearly separated, and the input waveform is It is possible to obtain N sample-and-hold output waveforms obtained by sampling in a wide band and at high speed and thinning out every Nth sample. Further, since there is only one input, it is not necessary to adjust the timing variation between analog inputs, and the sample and hold device for suppressing the influence of the timing variation is unnecessary.

The electro-optical sample according to claim 2
According to the holding device, in the electro-optical sample and hold device according to claim 1, N input terminals for inputting output electric signals of the N photo detectors and one output to the output side of the N photo detectors. Since we decided to provide an analog adder equipped with a terminal, there is no unnecessary high frequency component contained in the output waveform, and after holding one sample value of this output waveform for a certain period of time, reset the level one by one. It is possible to obtain a waveform that promptly shifts to the next sample value without passing through. Therefore, there is no need for extra adjustment points such as the delay amount as in the past.
It is possible to facilitate the interface with other devices connected to the latter stage of this device. Also, the cycle of the reset signal of each light receiver is 1 / of the total sampling cycle.
N is sufficient, and the operation speed can be improved.

As described above, the electro-optical sample and hold device of the present invention can realize high speed, low cost, miniaturization and simplification of design of a system in the field of digital information processing equipment including measurement equipment. It is possible to exert a great effect of being able to.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of an electro-optical sample and hold device according to claim 1 of the present invention and an operation waveform of a photodetector.

FIG. 2 is a schematic configuration diagram showing an embodiment of the electro-optical sample and hold device according to claim 2 of the present invention.

FIG. 3 is a schematic configuration diagram in which the electro-optical sample and hold device according to claim 2 of the present invention is applied to an actual A / D conversion system, and a diagram showing a differential output waveform by computer circuit simulation.

FIG. 4 is a diagram showing a schematic configuration of a conventional electro-optical sample and hold device and an operation waveform of a light receiver.

FIG. 5 is a diagram showing a configuration and an operation thereof when a light receiver of a conventional electro-optical sample and hold device is replaced with another light receiver having a hold function.

FIG. 6 is a configuration diagram of an A / D conversion system using a conventional interleave format.

[Explanation of symbols]

 21, 31, 41 Electro-optical sample and hold device 22 Light source 23 Optical modulator 24, 25 Light receiver 32 2-input analog adder 42 Level shift circuit 43 Output buffer amplifier

Claims (2)

[Claims] 1. A light source for generating an optical pulse train having a constant period and a constant intensity, an optical input / output terminal, and an electric input terminal, and sample and hold processing is performed on the intensity of a light beam emitted from the light source. An optical modulator that changes and emits light according to an input electric signal, and is provided corresponding to each light beam emitted from the optical modulator and divided into N pieces, and converts the light intensity of the light ray into an electric signal. , N having a function of integrating the electric signal and a reset function of returning the integration amount to zero at a constant cycle (where N ≧
2) optical receiver, and these N optical receivers are: k + (i-1) Nth pulse of the optical pulse train of the kth optical receiver (where 1 ≦ k ≦ N) From immediately after (k
+1) + (i-1) time that starts immediately before the arrival of the Nth pulse and ends in the period immediately after the arrival of the (k-1) + iNth pulse and immediately before the arrival of the k + iNth pulse An electro-optical sample and hold device, characterized in that the reset timing of each of the N optical receivers is set so that the band is in a reset state. 2. The electro-optical sample and hold device according to claim 1, wherein N input terminals and one output terminal for inputting output electric signals of the photodetectors to the output sides of the N photodetectors. An electro-optical sample and hold device comprising: an analog adder comprising: