JPH0641393Y2 - Diglitch D / A converter - Google Patents

Description

[Detailed Description of the Invention] TECHNICAL FIELD The present invention relates to a D / A that converts a digital signal into an analog signal.
The present invention relates to an A (digital / analog) converter, and more particularly to a deglitched D / A converter that converts code data such as binary code data expressed in a floating point format into an analog signal while suppressing glitch noise.

BACKGROUND ART Conventionally, there has been a circuit shown in FIG. 1 as a circuit of this type. In the figure, a signal (A) corresponding to the mantissa part of a digital signal corresponding to, for example, binary code data displayed in a floating point format is supplied to the D / A conversion circuit 1. Further, a signal corresponding to the exponent part of the digital signal is supplied to the variable gain amplifier 2. D / A conversion circuit 1
The analog output signal (B) is supplied to the deglitching circuit 3. The deglitching circuit 3 has a digglitch signal (C).
A discrete signal (D) which is closed in accordance with the above is removed of glitch noise contained in the analog output signal (B) and is supplied to the variable gain amplifier 2. The variable gain amplifier 2 changes the amplification gain according to the value of the exponent, amplifies the output signal (D) of the deglitching circuit 3, and outputs it as an analog output. A time chart of main signals is shown in FIG.

Next, the operation will be described with reference to FIG. Third
The figure shows an example of a digital signal displayed in a floating point format with a mantissa part 4 bits and an exponent part 3 bits. For example, a case where the mantissa part of the signal is “0011” and the exponent part is “001” will be described. The D / A conversion circuit to which the mantissa “0011” is input outputs 3 [V]. This output is the deglitching circuit 3
Is supplied to the variable gain amplifier 2 via. At the same time, "001" in the exponent part is supplied to the variable gain amplifier 2 to set the gain of the amplifier to 2 and output 6 [V]. When a binary number whose mantissa part is displayed as “0011” and exponent part is displayed as “001” is displayed as a decimal number, (0 × 2 ³ + 0 × 2 ² +
1 × 2 ¹ + 1 × 2 ⁰ ) × 2 ¹ = 6, which corresponds to the output of the variable gain amplifier 2.

The conventional circuit configured in this way requires a variable gain amplifier or an analog multiplier that changes the gain according to the value of the exponent, but such a device has a complicated circuit configuration and a large number of parts, and therefore consumes less power. However, it has the disadvantage of being expensive and expensive.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a D / A converter that converts a digital signal expressed in a floating point format into an analog signal, which is relatively inexpensive and can operate with low power consumption. It is to be.

In order to achieve the above object, in the D / A converter of the present invention, the switching circuit is closed to intermittently pass the analog signal obtained by D / A converting the value of the mantissa part of the input code data signal. The period is controlled according to the value of the exponent, and the average value of the analog signals that have passed through this switching circuit is obtained.

Embodiment An embodiment of the present invention will be described with reference to FIG. In the figure, parts equivalent to those of the conventional circuit shown in FIG. The digital signal (A) corresponding to the mantissa part of the binary code data displayed in the floating point format is D /
It is supplied to the A conversion circuit 1 and converted into an analog output signal (B). This analog output signal (B) is supplied to the deglitching circuit 3. On the other hand, the digital signal corresponding to the exponent part is supplied to the control circuit 4. In addition, the control circuit 4
Is supplied with a deglitch signal (C). Control circuit 4
Generates a control pulse signal (E) which is generated at the rising edge of the pulse of the deglitching signal (C) and whose pulse width changes in proportion to the digital signal value of the exponent part, and which generates the control pulse signal (E). Supply to the control input terminal of. FIG. 5 shows an example in which the pulse width of the control pulse signal (E) is changed with respect to the pulse width of the reference deglitch signal (C). The digglitch circuit 3 relays the analog output signal (B) to the average value circuit 5 only when the control pulse signal (E) is supplied, and otherwise outputs a predetermined reference level, for example, a ground voltage.
The average value circuit 5 outputs the average level value of the supplied signal voltage level, for example, the average value of the level in the period corresponding to the maximum pulse width of the control pulse signal (E).

Further, the operation of the circuit will be described with reference to FIG. FIG. 6 shows an output waveform of the deglitching circuit 3 when the binary data displayed in the floating point format shown in FIG. 3 is sequentially supplied to the circuit of the embodiment. In the figure, when the mantissa part of the supplied binary value is "0011" and the exponent part is "001", for example, the output of the D / A conversion circuit 1 is 3, and the control pulse signal (E) is Since the pulse width is 2 ¹ = 2, the output of the deglitching circuit 3 is the pulse signal (a). Similarly, when the mantissa part is “0101” and the exponent part is “000”, the pulse signal (b) has an amplitude of 5 and a pulse width of 1. Also, the mantissa part is “1011” and the exponent part is “01”.
When it is 0 ", the pulse signal (c) has an amplitude of 11 and a pulse width of 4. These pulse signals (a), (b)
The average values of (c) and (c) are 1.5, 1.25 and 11, respectively, when the maximum pulse width is 4, and are output from the average value circuit 5 as 1/4 of each analog output shown in FIG. Each of the above average values is shown by a dotted line in FIG. In this way it is possible to obtain an analog value proportional to the value of the digital signal displayed in floating point format.

The supplied floating-point code data is not limited to the binary code, and any analog output value corresponding to the supplied code may be set in advance.

Effect of the Invention As described above, the deglitched D / A according to the present invention
In the converter, the analog signal obtained by D / A converting the value of the mantissa part of the digital signal corresponding to the supplied code data displayed in floating point format has a length corresponding to the value of the exponent part. Since it is configured to output only the period of time and output the average value of this output, the circuit configuration is simpler and less expensive than the conventional D / A converter that converts a binary number in the floating point format into an analog signal. In addition, the power consumption is low, which is preferable.

[Brief description of drawings]

FIG. 1 is a block diagram of a conventional circuit, FIG. 2 is a time chart of main signals, FIG. 3 is a diagram for explaining the operation of the conventional circuit, and FIG. 4 is an embodiment of the present invention. FIG. 5 is a waveform diagram showing the deglitching pulse signal (C) and control pulse signal (E) of the control circuit, and FIG. 6 is a waveform diagram of the deglitching circuit output. Explanation of symbols of main parts 1 …… D / A conversion circuit 2 …… Variable gain amplifier 3 …… Diglitch circuit 4 …… Control circuit 5 …… Average value circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-58-151106 (JP, A) JP-A-56-10738 (JP, A) JP-A-57-23321 (JP, A) JP-A-60- 100831 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A deglitched D / A converter which outputs an analog value corresponding to code data consisting of a mantissa part and an exponent part which are supplied while preventing glitch noise from being generated in response to a deglitch pulse. A D / A conversion circuit that outputs an analog signal according to the digital value of the mantissa part of the A switching circuit that intermittently passes the analog signal according to the control pulse signal, and an average value circuit that outputs an average value of the signal that has passed through the switching circuit. A converter.