Analog-to-digital conversion device

Details Analog-to-digital conversion device Analog-to-digital conversion device

1998-05-01

2001-02-13

Tokar, Michael (Department: 2819)

Coded data generation or conversion

Analog to or from digital conversion

Analog to digital conversion

C341S155000

Reexamination Certificate

active

06188346

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an analog-to-digital conversion device for converting an analog signal into a digital signal, a binary code.
As a conventional ultra-high-speed analog-to-digital converter (analog-to-digital conversion device), for example, a parallel comparison type (flash type) analog-to-digital converter, like the one shown in
FIG. 20
, has been used (reference: Kazuo Kurokawa, Comp., “Analog IC Application Handbook”, Industrial Investigation Committee, 1976, p. 333”). This analog-to-digital converter is constituted by voltage comparison circuits for comparing the magnitude of an analog input signal with a plurality of reference voltages prepared in advance and outputting each result in the form of a binary signal representing “0” or “1”, and conversion circuits for encoding the respective binary outputs into a common binary code.
More specifically, the converter shown in
FIG. 20
has been proposed as a 4-bit parallel comparison type analog-to-digital converter designed to convert an analog signal V
in
into a 4-bit binary code. This converter includes 16 (=4
2
) voltage comparison circuits C
1
to C
16
having input terminals. The analog signal V
in
from an input terminal T
1
is supplied to one input terminal of each voltage comparison circuit.
This converter also has 16 voltage-dividing resistors R
1
to R
16
connected in series between power supply terminals E
1
and E
2
. Each of reference voltages obtained at the nodes of the resistors R
1
and R
2
, R
2
and R
3
. . . , R
15
and R
16
is applied to the other input terminal of a corresponding voltage comparison circuit (C
1
to C
15
). In addition, a reference voltage obtained on the opposite side of the resistor R
16
to the resistor R
15
is applied to the other input terminal of the voltage comparison circuit C
16
.
This converter also includes 15 (4
2
−1) NOR circuits NOR
1
to NOR
15
each having two input terminals. These NOR circuits are connected as follows.
First of all, the negative output from the voltage comparison circuit C
1
and the positive output from the voltage comparison circuit C
2
are supplied to the two input terminals of the NOR circuit NOR
1
.
The negative output from the voltage comparison circuit C
2
and the positive output from the voltage comparison circuit C
4
are supplied to the two input terminals of the NOR circuit NOR
2
.
The negative output from the voltage comparison circuit C
3
and the positive output from the voltage comparison circuit C
4
are supplied to the two input terminals of the NOR circuit NOR
3
.
The negative output from the voltage comparison circuit C
4
and the positive output from the voltage comparison circuit C
8
are supplied to the two input terminals of the NOR circuit NOR
4
.
The negative output from the voltage comparison circuit C
5
and the positive output from the voltage comparison circuit C
6
are supplied to the two input terminals of the NOR circuit NOR
5
.
The negative output from the voltage comparison circuit C
6
and the positive output from the voltage comparison circuit C
8
are supplied to the two input terminals of the NOR circuit NOR
6
.
The negative output from the voltage comparison circuit C
7
and the positive output from the voltage comparison circuit C
8
are supplied to the two input terminals of the NOR circuit NOR
7
.
The negative output from the voltage comparison circuit C
8
and the positive output from the voltage comparison circuit C
16
are supplied to the two input terminals of the NOR circuit NOR
8
.
The negative output from the voltage comparison circuit C
9
and the positive output from the voltage comparison circuit C
10
are supplied to the two input terminals of the NOR circuit NOR
9
.
The negative output from the voltage comparison circuit C
10
and the positive output from the voltage comparison circuit C
12
are supplied to the two input terminals of the NOR circuit NOR
10
.
The negative output from the voltage comparison circuit C
11
and the positive output from the voltage comparison circuit C
12
are supplied to the two input terminals of the NOR circuit NOR
11
.
The negative output from the voltage comparison circuit C
12
and the positive output from the voltage comparison circuit C
16
are supplied to the two input terminals of the NOR circuit NOR
12
.
The negative output from the voltage comparison circuit C
13
and the positive output from the voltage comparison circuit C
14
are supplied to the two input terminals of the NOR circuit NOR
13
.
The negative output from the voltage comparison circuit C
14
and the positive output from the voltage comparison circuit C
16
are supplied to the two input terminals of the NOR circuit NOR
14
.
The negative output from the voltage comparison circuit C
15
and the positive output from the voltage comparison circuit C
16
are supplied to the two input terminals of the NOR circuit NOR
15
.
This analog-to-digital converter includes an OR circuit OR
1
having eight input terminals, an OR circuit OR
2
having four input terminals, and an OR circuit OR
3
having two input terminals. The outputs from the NOR circuits NOR
1
, NOR
3
, NOR
5
, NOR
7
, NOR
9
, NOR
11
, NOR
13
, and NOR
15
are supplied to the eight input terminals of the OR circuit OR
1
. The outputs from the NOR circuits NOR
2
, NOR
6
, NOR
10
, and NOR
14
are supplied to the four input terminals of the OR circuit OR
2
. The outputs from the NOR circuits NOR
4
and NOR
12
are supplied to the two input terminals of the OR circuit OR
3
.
In this analog-to-digital converter, the output from the OR circuit OR
1
is output as the first (least significant) bit of a 4-bit binary code B to a bit terminal b
4
. Similarly, the output from the OR circuit OR
2
is obtained as the second bit of the binary code B at a bit terminal b
3
. The output from the OR circuit OR
3
is obtained as the third bit of the binary code B at a bit terminal b
2
. The output from the NOR circuit NOR
8
is obtained as the fourth (most significant) bit of the binary code B at a bit terminal b
1
.
According to the above analog-to-digital converter, the analog signal V
in
can be converted into the binary code B consisting of the four bits at the bit terminals b
4
to b
1
.
In the above conventional analog-to-digital converter, however, to convert the analog signal V
in
into the 4-bit binary code B, the following many elements are required: the 16 voltage comparison circuits C
1
to C
16
, the 16 resistors R
1
to R
16
, the 15 NOR circuits NOR
1
to NOR
15
, and the three OR circuits OR
1
to OR
3
.
When, therefore, the conventional analog-to-digital converter and other circuit devices are to be integrated into a monolithic unit on one substrate, the analog-to-digital converter occupies a large area, interfering with an increase in integration degree. In addition, since many elements are required, the power consumption becomes large. This inhibits an increase in operation speed.
SUMMARY OF THE INVENTION
It is, therefore, a principal object of the present invention to provide an analog-to-digital conversion device which is constituted by a small number of elements and can operate at high speed with low power consumption.
In order to achieve the above object, according to an aspect of the present invention, there is provided an analog-to-digital conversion device comprising quantization means for sampling an input analog signal at a predetermined period to obtain a sample, quantizing the sample into a (n+1)-valued signal with n (n is a natural number not less than two) thresholds, and outputting the quantized value, and binarization means for converting the (n+1)-valued quantized value output from the quantization means into a binary code.
With this arrangement, an input analog signal is temporarily quantized into a (n+1)-valued signal, which is then converted into a binary code. As a result, the input analog signal is converted into a digital signal.
According to another aspect of the present invention, there is provided an analog-to-digital conversion device compris

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