Analog to digital conversion device

Details Analog to digital conversion device Analog to digital conversion device

2002-04-11

2003-04-29

Young, Brian (Department: 2819)

Coded data generation or conversion

Analog to or from digital conversion

Analog to digital conversion

C341S139000

Reexamination Certificate

active

06556163

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Taiwan application Ser. No. 90205852, filed Apr. 13, 2001.
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention generally relates to an analog to digital conversion device, and more particularly, to an analog to digital conversion device integrated in a microcontroller that is accomplished on a single chip.
2. Description of Related Art
The analog to digital converter is widely used in current digital circuits. Most microcontrollers have an analog to digital converter to perform the analog to digital conversion operation.
FIG. 1
schematically shows a functional block sketch map of a conventional microcontroller
10
that is accomplished on a single chip and comprises an analog to digital converter
101
. The specification of the general analog to digital converter comprises a reference voltage and a bit number of the output digital signal. In order to describe clearly, the analog to digital converter
101
is exemplified hereinafter as the 8-bit analog to digital converter having the reference voltage 5 V, that means the acceptable range of the input analog signal is 5 V, and the output digital signal is 8 bits, so the resolution of the analog to digital converter is 5 V/255 (i.e. 2
8
−1)=19.6 mV. Therefore, under normal circumstances, the 8-bit analog to digital converter is suitable for converting the analog signal having the voltage intensity from 0 V to 5 V into a digital signal of 0 to 255 and outputs it. However, because of the variance of the application fields, there exists a big variance in the voltage intensity of the input analog signal. For example, if the input analog signal is 75+75 sin(wt) mV, that is, a sine analog signal having a peak value of only 150 mV, the maximum value of the digital signal output from the analog to digital converter mentioned above is 8(150/19.6=7.653), further resulting in the defect of poor total utilization (9/256) and resolution caused by the signal intensity being too small.
In consideration of the cost, it is not feasible to increase the bit number of the analog to digital converter. Moreover, the conversion time needed for the analog to digital converter having a larger bit number is also increased, and it also demands a larger amount of the operation current for its work. Based on the factors mentioned above, how to solve the defects in the prior art mentioned above without having to increase the physical bit number is the major objective of the present invention.
SUMMARY OF THE INVENTION
The present invention provides an analog to digital conversion device integrated in a microcontroller that is accomplished on a single chip, the device comprising: an adjustable gain amplifier, used to obtain a corresponding analog voltage signal V
1
−V
2
after corresponding an input analog voltage V
1
to a reference voltage V
2
, and based on a corresponding relationship of a gain function A, performing an amplification operation to a corresponding analog voltage signal, and further outputting an amplified analog voltage signal A(V
1
−V
2
); and a n-bit analog to digital converter, having a reference voltage Vr, electrically coupling to an output of the adjustable gain amplifier, used to convert the amplified analog voltage signal into a digital voltage signal, and outputting the digital voltage signal, wherein the gain function of the adjustable gain amplifier can be provided to the microcontroller to perform an adjustment according to the reference voltage Vr and a relationship of a peak value of the corresponding input analog voltage signal, further obtaining a better digital signal resolution.
According to the concepts mentioned above, the adjustable gain amplifier in the analog to digital conversion device comprises an operational amplifier, a fixed resistor R
1
, and a variable resistor R
2
, wherein the operational amplifier has an inverse phase input terminal, a non-inverse phase input terminal, and an output terminal. The analog voltage signal V
1
inputs into the non-inverse phase input terminal, and the output terminal couples to the n-bit analog to digital converter. The fixed resistor R
1
electrically couples in between the ground where the reference voltage V
2
equals 0 and the inverse phase input terminal. The variable resistor R
2
that is electrically coupled in between the inverse phase input terminal and the output terminal is used to create the adjustable gain amplifier having a gain function A as (R
1
+R
2
)/R
1
.
According to the concepts mentioned above, the adjustable gain amplifier in the analog to digital conversion device comprises an operational amplifier, a fixed resistor R
1
, and a variable resistor R
2
, wherein the operational amplifier has an inverse phase input terminal, a non-inverse phase input terminal, and an output terminal. The analog voltage signal V
1
inputs into the non-inverse phase input terminal, and the output terminal couples to the n-bit analog to digital converter. The fixed resistor R
1
electrically couples in between the reference voltage V
2
and the inverse phase input terminal. The variable resistor R
2
that is electrically coupled in between the inverse phase input terminal and the output terminal is used to create the adjustable gain amplifier having a gain function A as (R
1
+R
2
)/R
1
that corresponds to the reference voltage V
2
.
According to the concepts mentioned above, the adjustable gain amplifier in the analog to digital conversion device comprises an operational amplifier, a load resistor RL, a npn transistor, a fixed resistor R
1
, and a variable resistor R
2
. Wherein the operational amplifier has an inverse phase input terminal, a non-inverse phase input terminal, and an output terminal. The analog voltage signal V
1
inputs into the inverse phase input terminal, the reference voltage V
2
inputs into the non-inverse phase input terminal. The load resistor RL electrically couples in between the analog voltage signal V
1
and the inverse phase input terminal. The npn transistor has a collector, an emitter, and a base. The collector of the npn transistor couples to the inverse phase input terminal, the emitter of the npn transistor couples to the output terminal, and the base of the npn transistor couples to the non-inverse phase input terminal. The fixed resistor R
1
electrically couples to the non-inverse phase input terminal. The variable resistor R
2
that is electrically coupled in between the output terminal and the fixed resistor R
1
is used to create the adjustable gain amplifier having a logarithmic gain function A as (R
1
+R
2
)/R
1
that corresponds to the reference voltage V
2
.
The other aspect of the present invention is an analog to digital conversion device that is integrated in a microcontroller, the device comprising: an adjustable gain amplifier, used to obtain a corresponding analog voltage signal V
1
−V
2
after corresponding an input analog voltage V
1
to a reference voltage V
2
, and based on a corresponding relationship of a gain function A, performing an amplification operation to a corresponding analog voltage signal, and further outputting an amplified analog voltage signal A(V
1
−V
2
); and a n-bit analog to digital converter, having a reference voltage Vr, electrically coupling to an output of the adjustable gain amplifier, used to convert the amplified analog voltage signal into a digital voltage signal, and outputting the digital voltage signal, wherein the gain function of the adjustable gain amplifier can be provided to the microcontroller to perform an adjustment according to the reference voltage Vr and a relationship of a peak value of the corresponding input analog voltage signal, further obtaining a better digital signal resolution.
According to the concepts mentioned above, all elements of the microcontroller in the analog to digital device are accomplished on a single chip.
According to the concepts mentioned above, the adjustable gain amplifier in the anal

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