JPH0394521A - Multiplex a/d conversion circuit - Google Patents

Abstract

PURPOSE:To improve the effect of saving of the number of analog circuits proportional to multiplex rate by providing an A/D converter to a data signal, and a gain control signal being gain information of a logarithmic amplifier, respectively. CONSTITUTION:A dynamic range of a signal is corrected by variable gain logarithmic amplifiers 1-1, 1-2-1-n and corrected into a conversion range of an D/A converter of the post-stage. n-Set of output signals of the logarithmic amplifiers 1-1, 1-2-1-n are multiplexed by an analog multiplexer(MUX) 2, and a high frequency component is eliminated by a low pass filter(LPF) 3 for loopback distortion prevention, its output is sampled and held by a sample-and- hold circuit (S/H) 4 and converted and outputted into a digital data through an A/D converter. Then the gain of the logarithmic amplifiers 1-1, 1-2-1-n is required for reproducing the data signal, then the gain control signal for the logarithmic amplifiers 1-1, 1-2-1-n is A/D-converted similarly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multiplexed A-D converter circuit, and more particularly to a multiplexed A-D converter circuit that multiplexes a plurality of input signals. [Prior Art] Conventionally, when converting multiple pieces of physical data from analog to digital, an ellipse as shown in Figure 2 has been used because each signal has a different dynamic range and bit precision. That is, n amplifiers 11-1 to 1 that amplify n input signals
1-n, -n for its output, and A-D converters 14-1 to 14-1 for converting the sample and hold output into digital values.
14-n and a multiplexer 15 for multiplexing n output signals.

[Problem to be solved by the invention]

In the above-mentioned conventional multiplexed A-D converter circuit, since individual input signals have different dynamic ranges and bit precisions, dedicated A-D converters are required for each, resulting in a complicated circuit structure. There are some drawbacks. Another disadvantage of such A-D converter circuits is that the analog part occupies most of the circuit, and even as integration technology improves and semiconductor processes become smaller, the analog part does not shrink, which hinders cost reduction. be.

[Means to solve the problem]

The multiplexing A-D conversion circuit of the present invention includes: n logarithmic amplifiers that compress and correct the dynamic range of n input analog signals; a first analog multiplexer that multiplexes the outputs of the logarithmic amplifiers; a first low-pass filter that removes high-frequency signals from the output of the analog multiplexer No. 1; a first sample-and-hold circuit that samples and holds the output data of the low-pass filter; and a first sample-and-hold circuit that samples and holds the output data of the first analog multiplexer; a first analog-to-digital converter for converting into a signal; a second analog multiplexer for multiplexing n gain control signals representing gain values of the n logarithmic amplifiers; and an output of the second analog multiplexer. a second low-pass filter that removes high-frequency components from the second low-pass filter; a second sample-and-hold circuit that samples and holds the output data of the second low-pass filter; and a second sample-and-hold circuit that converts the output of the second sample-and-hold circuit into a digital signal. and a second AD converter.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1 is an elliptical diagram of an embodiment of the present invention. Input 1, input 2, etc., which are n input signals, have their dynamic ranges corrected by variable gain logarithmic amplifiers 1-1, 1-2 to 1-n, and are converted by the A-D converter in the subsequent stage. The signal is corrected to within the range. The n output signals of the logarithmic amplifiers 1-1 to 1-n are connected to an analog multiplexer (MtJX>
2, high frequency components are removed by a low pass filter (LPF) 3 to prevent aliasing distortion, and the output is sampled and held by a sample hold circuit (S/H) 4, and passed through an A-D converter. The data is converted into digital data and output. Here, since the gain values of the logarithmic amplifiers 1-1 to 1-n are necessary for reproducing the data signal, the gain control signals of the logarithmic amplifiers 1-1 to 1-n are also analog-to-digital converted.

That is, the gain control signals of the logarithmic amplifiers 1-1 to 1-n are multiplexed by the analog multiplexer 6, and the LPF 7
The high-frequency components of the output are removed, the data is held by the S/H 8, and the data is converted to digital data by the A-D converter 9 and output. Therefore, the output is the multiplexed data signal and
A gain control signal for data signal reproduction is multiplexed and output in two series.

〔Effect of the invention〕

As explained above, the present invention has only one A-D converter for both the data signal and the gain control signal which is the gain information of the logarithmic amplifier, and the effect of saving analog circuits is achieved in proportion to the multiplexing ratio. It has the effect of being able to give.

[Brief explanation of drawings]

FIG. 1 is an elliptical diagram of an embodiment of the multiplexed A-D converter circuit of the present invention, and FIG. 2 is an elliptic diagram of a conventional multiplexed A-D converter circuit. 1-1~. 1-n... Logarithmic amplifier, 2, 6... Analog multiplexer, 3.7.12... Low pass filter, 4, 8.13... Sample hold circuit, 5,
9.14...A-D converter, 1 1-1-11-
n...Amplifier, 15...Multiplexer.

Claims (1)

[Claims] n logarithmic amplifiers for compressing and correcting the dynamic range of n input analog signals; a first analog multiplexer for multiplexing the outputs of the logarithmic amplifiers;
a first low-pass filter that removes high-frequency components from the output of the analog multiplexer; a first sample-and-hold circuit that samples and holds output data of the low-pass filter; and converting the output of the first sample-and-hold circuit into a digital signal. a first A-D converter for converting, and the n
a second analog multiplexer for multiplexing n gain control signals representing the gain values of the logarithmic amplifiers; a second low-pass filter for removing high frequency components from the output of the second analog multiplexer; a second sample-and-hold circuit that samples and holds the output data of the second low-pass filter; and a second sample-and-hold circuit that converts the output of the second sample-and-hold circuit into a digital signal.
Multiplexing A characterized by comprising a D converter.
-D conversion circuit.