JPH0713040U - Isolation amplifier - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize an isolation amplifier in which the frequency of an observable input signal is widened and measurement accuracy is improved. A parallel type AD converter, an input amplifier circuit including an electric / optical converting means, an optical transmitting means, an optical / electrical signal converting means, and a digital signal for obtaining the plurality of optical / electrical signal converting means. And a parallel DA converter for converting the time base signal into an analog signal, and an output circuit portion including a time base signal generation circuit for controlling the parallel AD converter and the parallel DA converter, and the time base signal is an optical transmission signal. An isolation amplifier which is designed to be sent to the input amplifier circuit side via the.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an isolation amplification device in which input and output are insulated.

[0002]

[Prior art]

 Conventionally, in this type of isolation amplifier, when transmitting from the input side to the output side while insulating it, the input signal is converted into serial digital data, which is isolated by an optical coupler and demodulated, or , The input signal was converted into an optical signal having a light intensity proportional to the analog voltage value, and the optical signal was transmitted by a photocoupler.

[0003]

[Problems to be solved by the device]

 However, when transmitting serial digital data, it takes time to transmit the signal, or when transmitting an optical signal whose intensity is proportional to the analog voltage value, it corresponds to the input signal at the main unit. There was a problem that the linearity of the signal value was poor. The purpose of the present invention is to solve such a problem and to realize an isolation amplifier in which the frequency of an observable input signal is widened and the measurement accuracy is improved.

[0004]

[Means for Solving the Problems]

 The present invention provides a parallel AD converter for converting an input signal into a digital signal of a plurality of bits, and a plurality of electric / optical devices provided corresponding to each bit of the digital signal converted by the parallel AD converter. An input amplifier circuit including a conversion unit, an optical transmission unit that transmits the output of the input amplification circuit for each bit, and a plurality of units that convert the optical signal for each bit transmitted by the optical transmission unit into an electric signal. A plurality of optical / electrical signal converting means, a parallel type DA converter for converting a digital signal obtained by the plurality of optical / electrical signal converting means into an analog signal, the parallel type AD converter and the parallel type DA converter Is an insulating amplifying device which has an output part consisting of a time base signal generating circuit for controlling the time base signal and sends the time base signal to the input amplifying circuit side via an optical transmission signal.

[0005]

[Action]

 Since the signal input by the input amplifier circuit is digitally converted by the parallel AD converter and then converted to electrical / optical and transmitted to the output part, an isolation amplifier device that can handle high-frequency input signals can be provided. realizable.

[0006]

【Example】

 Hereinafter, the isolation amplifier of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the isolation amplifier of the present invention. In the figure, reference numerals 1 and 13 denote band limiting filters, the band limiting filter 1 limits the band of an input signal, and the band limiting filter 13 cuts off unnecessary high frequency components of the output of the following digital / analog converter 10. Output.

Reference numeral 2 denotes a variable gain amplifier, which amplifies an input signal under a set condition. Reference numeral 3 denotes a parallel type analog / digital converter (hereinafter referred to as a parallel type AD converter) which converts the output of the variable gain amplifier 2 into a digital signal of a plurality of bits.

Reference numeral 6a denotes an electric / optical conversion means composed of a light emitting diode or the like, which converts a digital electric signal output from the parallel AD converter 3 into an optical signal.

Reference numeral 7b denotes an optical / electrical converting means, which inputs the optical signal from the electric / optical converting means 6a through an optical transmitting means 8 described later and converts it again into an electrical signal. A latch 9 temporarily holds the electric signal output from the optical / electrical converting means 7b. The digital / analog converter 10 (hereinafter referred to as a DA converter) 10 converts the output from the latch 9 into an analog signal.

Reference numeral 11 denotes a time base circuit, which outputs a time base signal for controlling the operations of the parallel AD converter 3, the DA converter 10 and the latch 9. A gain control circuit 12 outputs a signal for setting the amplification factor of the variable gain amplifier 2.

Of the signals output from the time base circuit 11, the time base signal sent to the parallel AD converter 3 and the signal output from the gain control circuit 12 are output from the electrical / optical conversion means 6b. The signal is output to the phase synchronization circuit 5 and the gain control circuit 4 via the transmission means 8 and the optical / electrical conversion means 7a. The optical transmission means 8 is specifically realized by an optical cable or an optical fiber.

A power transformer 14 supplies power from the output portion to the input amplifier circuit. The transformer 14 converts the DC voltage supplied to the output portion into an AC voltage, and supplies the AC voltage to the input amplifier circuit via the coil transformer. Further, the AC voltage supplied to this input amplifier circuit is converted into a DC voltage again and used as a power source in the input amplifier circuit. Although the power transformer 14 is used in the embodiment, the input amplifier circuit and the output section may have different DC power sources. With such a configuration, it becomes possible to widen the band of the input signal.

The operation in such a configuration will be described. The electric signal input from the input terminal passes through the band limiting filter 1 and is adjusted to a predetermined level by the variable gain amplifier 2.

The level-adjusted signal is converted by the AD converter 3 into a digital signal of a plurality of bits (hereinafter, referred to as “parallel data”). The digital conversion speed of the parallel AD converter 3 is determined by the clock signal output from the phase synchronization circuit 5.

The digital-converted parallel data is converted into an optical signal by the electrical / optical conversion means 6a bit by bit. Specifically, it is converted into a light on / off signal. This optical signal is insulated and transmitted to the output portion by the optical transmission means 8. Even if the output section and the input amplifier circuit are separated from each other, the optical transmission means 8 can efficiently transmit an optical signal to the output section.

At the output portion, this optical signal is input by the optical / electrical converting means 7b and converted into an electrical signal. This electrical signal is latched by the latch 9 for each bit in accordance with the latching time base signal output from the time base circuit 11. The latched digital data is input to the parallel DA converter 10, and is sequentially converted into an analog signal according to the DA conversion time base signal output from the time base circuit 11 by the clock signal having the same frequency as the time base signal. Is converted.

The band limiting filter 13 removes unnecessary high frequency noise from the electric signal returned to the analog signal. The output from the band limiting filter 13 is then input to the measurement system and the waveform is observed.

Although the band limiting filter 13 is connected to the output side of the parallel DA converter 10 in the embodiment, it may be connected to the input side of the DA converter 10 as a digital filter. Good. With such a configuration, the degree of freedom in the characteristics of the cutoff frequency of the output signal is increased. Alternatively, the data may be directly output as a plurality of bits of digital data without DA conversion, and the waveform may be observed based on the digital data.

It is also possible to change the AD conversion speed in the AD converter 3 by changing the frequency of the time base signal output from the time base circuit 11, and accompanying this, the band on the input side can be changed. An application example in which the filter frequency is variable is also conceivable.

In the input amplifier circuit, the input signal is AD-converted by the parallel AD converter 3 at the timing of the frequency f _i , and at the output portion, the transmitted multi-bit signal is converted into the frequency f ₀ ( A configuration is also possible in which DA conversion is performed by the parallel DA converter 10 and output at the timing of f _i ≠ f ₀ ). That is, the AD conversion frequency and the DA conversion frequency may be different. With such a configuration, for example, by making the conversion speed of the DA converter slower than the conversion speed of the AD converter, it is possible to reduce the power consumption of the entire isolation amplifier device.

A rate duser for converting a serial signal into a parallel signal is connected to the output of the parallel AD converter 3, whereby an integer multiple of the parallel data output from the parallel AD converter 3 is connected. An application example of a configuration for optically transmitting data converted into a bit width can also be considered.

With this configuration, the electrical signal may be converted into an optical signal at a rate that is a fraction of the conversion speed of the AD converter 3, and the optical signal may be transmitted at the same speed. It can handle high-speed input signals. For this reason, the electric / optical conversion means 6a and the like have a slower operating speed than the AD converter 3 in a normal insulation amplifier, and even if a high-speed AD converter is used, the frequency band of the measurable input signal is electric / optical. Although it was limited by the converting means 6a and the like, such limitation is eliminated, and it becomes possible to use an inexpensive electric / optical converting means.

In the embodiment, the optical signal is used for the transmission from the input amplifier circuit to the output portion, but the electric signal may be converted into an electromagnetic wave such as a microwave having a low frequency for transmission.

[0024]

[Effect of device]

 As described in detail above, the following effects can be obtained by the isolation amplifier of the present invention. First, since the parallel AD converter is used, the transmission rate of the input signal from the input amplifier circuit to the output portion can be increased.

For example, by using the present invention, in a measuring instrument or the like having an insulation amplification device in which an input amplification circuit and an output portion are insulated, an input signal can be sampled at 100 MHz, and data transmission can be performed. The amount is 100 Mbyte / sec. At this time, if the reproducible frequency of the DA converter 10 or the like in the output portion is set to 1 / 2.5, it becomes a band of 40 MHz.

Further, since the characteristics of the AD converter and the DA converter, their resolutions, and the conversion characteristics of the input signal are determined only by the reference voltage, the DC characteristics are higher than those of the analog method that directly converts the input signal into an optical signal. Can be greatly improved.

Furthermore, since an optical fiber or the like is used as a signal transmitting means between the input amplifier circuit and the output portion, even if the number of input coupling portions increases, the coupling capacitance does not increase, and thus CMRR ( It is possible to improve the in-phase signal rejection ratio).

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of an embodiment of the present invention.

[Explanation of symbols]

 1, 13 Band limiting filter 2 Gain variable amplifier 3 Parallel type AD converter 4, 12 Gain control circuit 5 Phase locking circuit 6a, 6b Electric / optical conversion means 7a, 7b Optical / electrical conversion means 8 Optical transmission means 9 Latch 10 Parallel Type DA converter 11 Time base circuit 14 Power transformer

Claims (1)

[Scope of utility model registration request] 1. A parallel AD converter for converting an input signal into a digital signal of a plurality of bits, and a plurality of electric / electrical converters provided corresponding to respective bits of the digital signal converted by the parallel AD converter. An input amplifier circuit including an optical conversion unit, an optical transmission unit that transmits the output of the input amplification circuit for each bit, and a plurality of units that convert the optical signal for each bit transmitted by the optical transmission unit into an electric signal. A plurality of optical / electrical signal converting means, a parallel type DA converter for converting a digital signal obtained by the plurality of optical / electrical signal converting means into an analog signal, the parallel type AD converter and the parallel type DA converter And an output circuit section including a time base signal generation circuit for controlling the time base signal, and the time base signal is sent to the input amplification circuit side via an optical transmission signal.