JP2001326575A - A/d converter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To A/D-convert an analog signal to an optimal digital signal in accordance with its specification. SOLUTION: This device is provided with an A/D converter circuit 12 to be supplied with an analog signal SANLG. This device is provided with a detection circuit 21 for detecting the feature of the signal SANLG and a generation circuit 22 for generating set data S12 on the A/D conversion characteristic of the circuit 12 from the detected output S21 of the circuit 21. The data S12 is supplied to the circuit 12 and its A/D conversion characteristic is set to be characteristic corresponding to the feature of the signal SANLG.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an A / D converter.

[0002]

2. Description of the Related Art An A / D converter circuit is used to convert an analog signal such as an audio signal or a video signal into a digital signal. In addition, there are various types of A / D conversion methods of the A / D converter circuit. In some cases, the A / D converter circuit is integrated into an IC.
In some cases, an IC is formed integrally with another circuit.

[0003]

The analog signal has a difference in the dynamic range in the amplitude direction and the dynamic range in the frequency direction depending on the purpose of use. Further, the digital signal also has a different number of quantization bits and a different sampling frequency according to the purpose of use. Therefore, when an analog signal is A / D converted into a digital signal, the number of quantization bits and the sampling frequency differ depending on the purpose of use.

For example, even when A / D conversion is performed on an analog audio signal into a digital audio signal, the number of quantization bits is 16 bits or 20 bits, and the sampling frequency is 44.1 kHz or 48 kHz. . FIG. 5 shows the required number of quantization bits and signal bandwidth for a video signal, for example.

In general, when an analog signal is A / D-converted, an A / D converter circuit whose specifications such as the number of quantization bits and the sampling frequency are somewhat higher than those of the input analog signal is prepared. And
A / D conversion according to the purpose is performed within the specification.

Therefore, when the specifications of analog signals are changed according to the purpose of use, or when a plurality of analog signals having different specifications are selectively supplied, A / D converter circuits corresponding to the respective analog signals are required. ,
As a result, an increase in cost and a decrease in space factor are caused.

It is also conceivable to use a single A / D converter circuit and to increase the specifications such as the number of quantization bits and the sampling frequency so that any A / D conversion can be performed. In that case, the operation speed becomes higher than necessary, and wasteful power consumption increases,
Unnecessary radiation noise increases.

The present invention is to solve such a problem.

[0009]

According to the present invention, for example, an A / D converter circuit to which an analog signal is supplied, a detection circuit for detecting characteristics of the analog signal, and the A / D converter based on a detection output of the detection circuit. And a generation circuit for generating setting data of A / D conversion characteristics of the A / D converter circuit, wherein the setting data is supplied to the A / D converter circuit, and the A / D conversion characteristics are converted into characteristics of the analog signal. The A / D converter device is set to have the corresponding characteristics. Therefore, the A / D conversion characteristics are optimized according to the input analog signal.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG.
/ D indicates an analog signal to be converted. Then, the analog signal SANLG is supplied from an input terminal 11 to an A / D converter circuit 12 and A / D converted into a predetermined digital signal SDGTL. The signal SDGTL is taken out to an output terminal 14 through a digital filter 13. in this case,
The A / D conversion characteristics of the A / D converter circuit 12 and the filter characteristics of the digital filter 13 are optimized by the control circuit 22 according to the characteristics of the input analog signal SANLG.

That is, the analog signal S from the terminal 11
ANLG is supplied to the detection circuit 21, and characteristics of the analog signal SANLG, for example, information on the amplitude and frequency component of the signal SANLG are extracted as a detection signal S21. In this case, the amplitude of the analog signal SANLG is the A / D
The frequency component corresponds to the number of quantization bits at the time of conversion, and the frequency component corresponds to the sampling frequency.

The detection signal S21 is supplied to the DSP 22, and when the analog signal SANLG is A / D-converted to the digital signal SDGTL, setting data S12 for optimally performing the A / D conversion is calculated. Further, in the DSP 22, data S13 for setting the characteristics of the digital filter 13 is calculated based on the detection signal S21.

In this case, for example, as shown in FIG. 2A, when the occurrence probability is high when the amplitude of the analog signal SANLG is medium, and as shown in FIG. Setting data S1 so that
2. S13 can be generated. Also, for example, FIG.
As shown in FIG. 3B, when the occurrence probabilities of the low band and the high band of the analog signal SANLG are high, and as shown in FIG. Can be generated.

Then, the data S12 is supplied to the A / D converter circuit 12, and its A / D conversion characteristics, for example, A
The number of quantization bits and the sampling frequency at the time of the / D conversion are set to the optimum values, and the data S13 is supplied to the digital filter 13, and the filter characteristics, for example, the cutoff frequency are set to the optimum values.

Thus, according to the above-described device, the A / D conversion characteristics of the A / D converter circuit 12 and the filter characteristics of the digital filter 13 are converted into the analog signal S
Since the digital signal SDGTL is changed to the optimum value according to the characteristics of ANLG, the output digital signal SDGTL can have necessary and sufficient specifications.

Further, even if the input analog signal SANLG has a difference in the dynamic range in the amplitude direction and the dynamic range in the frequency direction depending on the purpose of use, an appropriate digital signal SDGTL can be obtained.

Further, even when the specification of the analog signal SANLG is changed, or when a plurality of analog signals having different specifications are selectively supplied, there is no need to prepare an A / D converter circuit corresponding to each. In addition, it is possible to suppress an increase in cost and a decrease in space factor. Even if the number of the A / D converter circuits 12 is one, the operation speed is not required more than necessary, so that there is no increase in wasteful power consumption and unnecessary radiation noise.

FIG. 4 shows a memory 23 instead of the DSP 22.
Is provided. That is, in the memory 23,
A conversion table indicating the correspondence between the detection signal S21 and the setting data S12, S13 is prepared, and the detection signal S21 is converted into the setting data S12, S13 and output by referring to the conversion table.

Therefore, also in this case, the optimum A / D conversion can be performed similarly to the apparatus of FIG.
Since no DSP is used, the cost can be reduced.

In the above description, the setting data S12, S
13 may be data to be set so that when they indicate a change in the number of quantization bits or the sampling frequency, the number of quantization bits or the sampling frequency is not changed evenly, for example, at a logarithmic interval. . In the above description, the input analog signal S
The detection signal S21 indicating the characteristic is formed from ANLG, but the digital signal SDGTL output from the digital filter 13 is generated.
From the detection signal S21 indicating the characteristics of the input analog signal SANLG
Can also be formed.

[List of abbreviations used in this specification] A / D: Analog to Digital DSP: Digital Signal Processor IC: Integrated Circuit kHz: kiloHertz Bit: binary digit

[0022]

According to the present invention, A / D conversion can be performed to an optimal digital signal corresponding to an input analog signal. At this time, an appropriate digital signal can be obtained even if the input analog signal has a difference in the dynamic range in the amplitude direction or the dynamic range in the frequency direction depending on the purpose of use.

Further, it is possible to suppress an increase in cost and a decrease in space factor. Further, unnecessary power consumption does not increase, and unnecessary radiation noise does not increase.

[Brief description of the drawings]

FIG. 1 is a system diagram illustrating one embodiment of the present invention.

FIG. 2 is a characteristic diagram for explaining the present invention.

FIG. 3 is a characteristic diagram for explaining the present invention.

FIG. 4 is a system diagram showing another embodiment of the present invention.

FIG. 5 is a characteristic diagram for explaining the present invention.

[Explanation of symbols]

11 input terminal, 12 A / D converter circuit, 13
Digital filter, 14 output terminal, 20 control circuit,
21: detection circuit, 22: DSP, 23: memory

Claims (4)

[Claims] 1. An A / D converter circuit to which an analog signal is supplied, a detection circuit for detecting a characteristic of the analog signal, and an A / D conversion characteristic of the A / D converter circuit based on a detection output of the detection circuit. A generation circuit for generating setting data, wherein the setting data is supplied to the A / D converter circuit, and the A / D conversion characteristic is set to a characteristic corresponding to the characteristic of the analog signal. D converter device. 2. The A / D converter according to claim 1, further comprising a digital filter, wherein said generation circuit sets a filter characteristic of said digital filter from a detection output of said detection circuit. Data is generated, an output signal of the A / D converter circuit is taken out through the digital filter, and the another setting data is supplied to the digital filter, and the filter characteristic is changed to a characteristic corresponding to the characteristic of the analog signal. A / D converter device to be set. 3. The A / D according to claim 1 or claim 2.
In the converter device, the characteristic of the analog signal is at least one of an amplitude and a frequency component of the analog signal, and the A / D conversion characteristic is at least one of a quantization bit number and a sampling frequency. D converter device. 4. The A / D according to claim 2 or 3.
An A / D converter device, wherein the filter characteristics are set to characteristics corresponding to the number of quantization bits and the sampling frequency of the A / D converter circuit.