JPH03276931A - Analog signal transmission circuit - Google Patents

Abstract

PURPOSE:To improve S/N and the linearity with less inherent noise and to make a band broad by extracting and latching an analog signal to be sent at a frequency being a half of a reference pulse signal frequency of above. CONSTITUTION:Linear voltage generating circuits 12, 14 generate respectively linear voltage signals 1, 2 synchronously with a reference pulse generating circuit 13. A comparator 11 compares an analog signal to be sent with the linear voltage signal 1 and generates an output pulse when the amplitude of both signals is equal to each other. A sample-hold circuit 15 extracts and holds the amplitude of the linear voltage signal 2 at a time when an output pulse comes and a filter circuit 16 smoothes it. Thus, an analog signal to be sent delayed by one period for a reference pulse signal is obtained at the output of the filter circuit 16.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an analog signal transmission circuit.

(Prior art and its problems) In general, when transmitting an analog signal generated in a system with one potential to a system with another potential, the conventional analog method uses a chopper circuit etc. The analog signal was converted into alternating current, and the original analog signal was reproduced by demodulating it after transmission using an isolation transformer or the like.

However, in this method, the constant of the low-pass filter for suppressing the rip component in the output signal must be chosen to be significantly larger than the chopper period, which limits the signal band and makes it difficult to widen the band. Met.

(Problems to be Solved by the Invention) Generally, the performance of an analog transmission circuit can be evaluated from the transmission band, inherent noise, noise range, linearity thereof, and the like. In the conventional method, the transmission band is the chopper frequency 1/
100 to 1/10000, the inherent noise is determined by the ripple component, and the linearity is mainly dominated by the characteristics of the isolation transformer.

In particular, the relationship between these two is antinomic, as the transmission band becomes narrower when the inherent noise is reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wideband analog signal transmission circuit that has essentially little inherent noise, good signal-to-noise ratio and linearity.

(Means for solving the problem) The above-mentioned problem is to simultaneously generate linear voltage signals in two systems with different characteristic potentials, compare the negative linear voltage signal with the transmitted analog signal, and compare both signals. This is solved by extracting and holding the other linear voltage signal at the time when the amplitudes of the two lines become equal. Specifically, a reference pulse signal generation circuit that generates pulses with a predetermined period, two linear voltage generation circuits that generate linear voltage signals in synchronization with this reference pulse signal, and a comparison between one linear voltage signal and the transmitted signal. death,
An analog signal that includes a comparator circuit that generates an output pulse at the time when the amplitudes of both signals are the same, a sample hold circuit that extracts and holds the amplitude of the other linear voltage signal using this output pulse, and a filter circuit that smoothes the output of the sample hold circuit. Solved by transmission circuit.

(Operation and Effects of the Invention) In the present invention, the analog signal to be transmitted is extracted and held at a frequency of f * / 2 or more with respect to the reference pulse signal frequencies f and l, and according to the sampling theorem, f
, /4 or less is guaranteed, and the smoothing filter circuit in this case is mainly used to suppress high-frequency noise that exceeds the signal band, and its capacity is equal to the standard. It was approximately the same as the pulse period (=1/fR), and thus a wide band was achieved. Furthermore, since the transmitted signal does not pass through a nonlinear element such as a transformer, an analog transmission circuit with a rich dynamic range and linearity and a high signal-to-noise ratio could be developed.

(Embodiment) The block circuit of FIG. 1, which is an embodiment of the present invention, will be described in detail below with reference to the operating waveforms of the main parts of FIG. 2.

The two linear voltage generating circuits 12 and 14 generate linear voltage signals -1 (Fig. 2(b)) and linear voltage signals -2 (Fig. 2(d)), respectively, in synchronization with the reference pulse generating circuit 13. . The comparator circuit 11 compares the transmitted analog signal with the linear voltage -1 (Fig. 2 (b)) and outputs a pulse (Fig. 2 (C)) at the time when the amplitudes of both signals are equal.
occurs.

The sample-and-hold circuit 15 extracts and holds the amplitude of the linear voltage signal -2 at the time when the output pulse arrives, and the filter circuit 16 smoothes it (FIG. 2(d)) and calculates the output of the filter circuit from 0 or more. A transmitted analog signal appears delayed by approximately one cycle of the reference pulse signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of each circuit for implementing the present invention. FIG. 2 is an operational waveform diagram of each main part in FIG. 1, where (a) is a reference pulse signal, (b) is a comparator (C) shows the relationship between the input signals of the circuit, (C) shows the output pulse of the comparator circuit, and (D) shows the relationship between the output signals of the sample and hold circuit and the filter circuit, respectively. (Explanation of symbols) 11...Comparator circuit, 12.14...Linear voltage generation circuit, 13...
... Reference pulse generation circuit, 15 ... Sample hold circuit, 16 ... Filter circuit. zenzlD time leap

Claims (1)

[Claims] a reference pulse signal generation circuit that generates pulses with a predetermined period;
Two linear voltage signal generation circuits generate voltages that change linearly over time in synchronization with this reference pulse signal, and the transmitted signal is compared with one linear voltage signal, and the time when the amplitudes of both signals become the same. An analog signal transmission circuit comprising: a comparator circuit that generates an output pulse; a sample-and-hold circuit that uses this output pulse to extract and hold the amplitude of the other linear voltage signal; and a filter circuit that smoothes the output of the sample-and-hold circuit.