TWI410052B - Analog to digital converter having amplified functions - Google Patents

Abstract

An Analog to Digital Converter having Amplified Functions is disclosed. The converter includes an instrumentation amplifier, a sampling & holding circcuit, an analog signal comparator, a successive approximation type digital signal controller, a switch array, a capacitance digital rectifying circuit, and a capacitance-electric-charge type dig ital analog signal converter. The signal converter system has the analog signal being amplified by the instrumentation amplifier and being sampled and filtered through the sampling & holding circuit, then, being sent to the comparator circuit for performing signal comparison to generate a digital control code. Thereafter, the digital control code is sent to the successive approximation type digital signal controller to generate the required digital signals. Finally, the digital signals are sent back to the digital analog converter circuit to acquire the corresponding analog signals. These analog signals, together with the original amplified signals are compared through the analog comparator to obtain the control code required by the control circuit. Accordingly, to reason by analogy, the last required 10 bits digital code will be generated after going through 11 clock signals.

Description

Analog digital converter with amplification function

The present invention relates to an analog digital signal converter, and more particularly to an analog digital signal converter having a signal amplification function.

Since the human physiological signal is an analog signal, the signal cannot be analyzed by the processor, so the analog signal needs to be converted into a digital signal accepted by the processor, so that the human physiological signal can be analyzed by the processor.

The traditional method of signal conversion is to convert the analog signal into a digital signal through a type of digital signal converter, but the human physiological signal is very weak, and the general converter design does not have the function of amplification (such as the Republic of China patent number) :200726094 and I231098), therefore, an external amplifier circuit is required to first amplify the signal and then convert it. In addition, the accuracy of analog digital signal converters is also the design focus. Most designs do not consider the accuracy problems caused by component numerical errors, which may cause accuracy deviations (such as the Republic of China patent number: I247487 and 200707915). ).

Therefore, it is necessary to provide an innovative and more advanced invention in combination with the above, if the amplifier circuit and the signal conversion circuit can be integrated without an external amplifier circuit, and the capacitor circuit is designed to correct the numerical error. Higher precision. This is the focus of design innovation in the present invention.

One of the objects of the present invention is to provide an analog digital converter having an amplification function, comprising an instrumentation amplifier and a signal conversion circuit. By integrating the amplifier and the signal conversion circuit, the input analog signal can be analogized via an internal amplifier. The signal is amplified, and then the amplified signal is sent to the signal conversion circuit for conversion.

Another object of the present invention is to provide a numerical correction design for a type-to-digital signal conversion circuit of an analog-to-digital converter having an amplification function. Since such a digital signal conversion circuit uses a capacitor charge charging and discharging structure, the capacitance causes a numerical error and causes a decrease in accuracy. Therefore, in this design, the calculation of the algorithm is performed, and then the result of the calculation of the algorithm is implemented by a hardware circuit, so that the error caused by the capacitance value can be corrected.

In order to achieve the above object, the signal conversion system architecture in the digital converter with the amplification function provided by the present invention further comprises: an instrument amplification circuit, a sample holding circuit, a analog signal comparison circuit, a digital signal control circuit, a switch array, a capacitor-charged digital analog converter, and a capacitance value correction circuit, wherein the meter amplifier circuit puts an analog signal Large, then input the signal to the signal conversion circuit.

Referring to FIG. 1, a preferred embodiment of the analog digital signal conversion system having the amplification function of the present invention comprises: an instrumentation amplifier (IA) 10 and a signal converter 11. The instrumentation amplifier 10 is composed of an operational amplifier, which is a simple amplifier whose amplification factor can be adjusted by an external resistor to determine the magnitude of the value. Therefore, the instrumentation amplifier (IA) 10 can amplify the small signal. . Moreover, the analog digital signal converter 11 is used to convert the analog signal after amplification into a digital signal that the processor can process.

2 is a preferred embodiment of the analog digital signal conversion system 11 of the present invention. As shown in FIG. 2, the signal converter 11 further includes: a sample and hold circuit 111, an analog signal comparator 112, a digital signal controller 113, a switch array 110, a capacitance-charged digital analog converter 114, and a Capacitance value correction circuit 115. The sample and hold circuit 111 can filter the input signal to obtain a more correct signal. The analog signal comparator 112 can compare the amplified input signal with the feedback signal to obtain a control signal of the digital signal controller. The digital signal controller 113 can obtain the converter ten The output of the bit digit code. The switch array 110 prevents signal attenuation. The capacitive-charged digital analog converter 114 converts the feedback digital signal into an analog signal and compares it with the input signal. The capacitance value correction circuit 115 can self-correct the capacitance value to obtain a more accurate value. The capacitance-charged digital analog converter further comprises eleven sets of capacitors, which can convert digital signals into analog signals by the characteristics of capacitance charging and discharging.

Referring to FIG. 3, the sample and hold circuit 111 further includes a first signal sampling capacitor 116, a first operational amplifier 117, a second signal holding capacitor 118, and a second operational amplifier 119. The first signal sampling capacitor 116 and the second signal holding capacitor 118 can perform sampling and holding operations; and the first operational amplifier 117 and the second operational amplifier 119 have a function of signal buffering. And the two sets of sampling capacitors 116, 118 and the two sets of operational amplifiers 117, 119 can be exchanged for sampling and holding.

As shown in FIG. 3, the sampling and holding circuit 111 is configured to receive the clock signal 401. When the positive half cycle comes, the first signal sampling capacitor 116 and the first operational amplifier 117 perform sampling operations. The second signal sampling capacitor 118 and the second operational amplifier 119 perform a holding operation; conversely, when the negative half cycle of the pulse signal 401 comes, the first signal sampling capacitor 116 and the first operational amplifier 117 perform a holding operation, and The second signal sampling capacitor 118 and the second operational amplifier 119 perform a sampling operation, so that the double sampling function can be achieved by repeating the operation.

Referring to FIG. 4, the analog signal comparator 112 can compare the amplified analog signal with the feedback signal to obtain the control signal of the digital signal controller 113. The analog signal comparator 112 further includes a bias circuit 301 and a differential pair comparator main circuit 302. The differential pair comparator main circuit 302 is supplied with a stable bias value via the bias circuit 301. If the bias value is unstable, the differential operation of the comparator main circuit 302 is caused. The differential pair comparator main circuit 302 can receive the voltage of the bias circuit 301 and compare the two analog input signals to generate a digital control signal. If the analog signal value output by the sample and hold circuit 111 is greater than the value of the feedback signal 402, the analog signal comparator 112 outputs the digital signal 0. If the analog signal value output by the sample and hold circuit 111 is less than the value of the feedback signal 402, the analog signal comparator 112 outputs the digital signal 1. Accordingly, the signal obtained by the analog signal comparator can control the action of the digital signal controller 113.

Referring to FIG. 5, the digital signal controller 113 is capable of generating a desired digital signal which is used to control the switch array 110 to generate the desired signal. The digital signal controller 113 further includes an upper sequence logic circuit 120 and a lower layer sequence logic circuit 121. The upper sequence logic circuit 120 A control signal can be generated to control the lower sequence logic circuit; and the lower sequence logic circuit 121 can generate a feedback signal and a tens digit code after receiving the control signal. The digital signal controller 113 is mainly controlled by the upper level shift register 120 to control the lower layer register 121. The controller operates on the principle that the initial value is first set to the logic circuit 120 via the upper sequence, the highest bit (MSB, Most Significant Bit) is set to 1, and the other bits are set to 0, that is, the value is set to two bits. The value is 10000000000. If the output signal of the analog signal comparator 112 is 1, the highest bit (MSB) will be reset to 0 and will remain until the end of the entire comparison period; conversely, if the output signal of the analog signal comparator 112 is 1, then The highest bit (MSB) will remain at 1. The rest of the bits are deduced by analogy. After the first bit comparison is completed, the second bit is compared. The time of one clock determines the value of one bit. The highest bit (MSB) at the beginning is Set to 1 first, then decide to keep 1 or 0 depending on the output of the analog signal comparator 112.

Referring to FIG. 6, the capacitance value correction circuit 115 further includes a correction capacitor 201 and a correction DAC circuit (Digital/Analog Converter) 202. Through the algorithm, the capacitance correction value can be calculated, that is, each capacitance error value of the capacitance-charged digital analog converter is calculated, and then added to the output portion to be charged and discharged, so that The capacitance error value of the capacitance-charged digital analog converter is corrected to correct the charge and discharge levels caused by the error value, and the accuracy is ensured. The correction DAC circuit 202 can convert the correction code into an analog voltage and then input it to the correction capacitor, so that an accurate signal can be obtained.

After the signal is amplified by the instrumentation amplifier 10, the signal is input to the sample and hold circuit 111, and the sample and hold circuit 111 filters the analog signal to obtain a more accurate signal, and then sends the signal to the analog signal. 112. The digital signals of 1 and 0 are obtained after comparing the voltage values, and the digital signals are used to control the operation of the digital signal controller 113. The output of the digital signal controller 113 is sent to the switch array 110, which is used to prevent the erroneous action of the capacitive-charged digital analog converter 114 due to signal attenuation. After the switch array 110 is added, the signal can be maintained at the level of 1.8V, and then the signal is sent back to the capacitance-charged digital analog converter 114, and after being converted, the output of the sample-and-hold circuit 111 is compared. Then, the comparison result is input to the digital signal controller 113, and the circuit operates in a loop, and after the eleven clock frequencies, the required tens digit code can be obtained.

The invention has the advantages of low complexity, low power consumption, self-correcting circuit and signal amplification. The converter system is very suitable for application in people's livelihood and medical workers. Industry use.

The preferred embodiments are merely illustrative of the technical contents of the present invention, and are not intended to limit the invention to the embodiments, and various changes are made in accordance with the spirit of the present invention and the circumstances listed in the following claims. All are within the scope of the invention.

10‧‧‧Instrument Amplifier

11‧‧‧ Analog Digital Signal Converter

110‧‧‧Switch array

111‧‧‧Sampling and holding circuit

112‧‧‧ analog signal comparator

113‧‧‧Digital Signal Controller

114‧‧‧Capacitive-charged digital analog converter

115‧‧‧Capacitance value correction circuit

116‧‧‧First sample hold capacitor

117‧‧‧First sample-and-hold op amp

118‧‧‧Second sample holding capacitor

119‧‧‧Second sample-and-hold op amp

120‧‧‧Upper sequence logic

121‧‧‧lower sequence logic

201‧‧‧correcting capacitor

202‧‧‧Correct DAC circuit

301‧‧‧bias circuit

302‧‧‧Differential pair comparator main circuit

401‧‧‧ clock signal

402‧‧‧Response signal

1 is a schematic diagram of an analog digital converter having an amplification function; FIG. 2 is a schematic diagram of an analog digital converter of the present invention; FIG. 3 is a schematic diagram of a sample and hold circuit of the present invention; FIG. 5 is a schematic structural diagram of a digital signal controller according to the present invention; FIG. 6 is a schematic diagram of a capacitor numerical value correcting circuit according to the present invention;

10‧‧‧Amplifier amplifier circuit

11‧‧‧ analog digital conversion circuit

Claims (5)

An analog digital converter with amplification function includes: an instrumentation amplifier for amplifying small signals; and an analog digital signal converter for converting the analog signal after amplification into a digital position that the processor can process The signal, the analog digital signal converter, further includes: a sample and hold circuit for filtering the input signal to obtain a relatively correct signal, the sample and hold circuit further comprising: two sets of sample and hold capacitors for sampling the signal The action of maintaining; and two sets of operational amplifiers for signal buffering; wherein the two sets of sampling capacitors are interchangeable with the two sets of operational amplifiers for sampling and holding. a type of analog comparator for comparing the amplified input signal with the feedback signal to obtain a control signal of the digital signal controller; and a digital signal controller for obtaining the output of the converter tens digit code; a switch array for preventing signal attenuation; a capacitance-charged digital analog converter for converting a feedback digital signal into an analog signal and comparing it with an input signal; and a capacitance value correction circuit for capacitor The values are self-corrected to obtain more accurate values. An analog digital converter having an amplification function as described in claim 2, wherein the analog signal comparator further comprises: a bias circuit for generating a stable voltage value; and a differential pair comparison The main circuit is configured to receive the voltage of the bias circuit and compare the two types of input signals to generate a digital control signal. For example, the analog digital converter with the amplification function described in claim 2, wherein the digital signal controller further comprises: a lower sequence logic circuit for receiving the control signal and generating the feedback signal and the tens digit. And an upper sequence logic circuit for generating a control signal to control the lower sequence logic circuit. Analog digital signal with amplification function as described in item 2 of the patent application scope The converter, wherein the capacitance-charged digital analog converter further comprises eleven sets of capacitors for converting digital signals into analog signals by the characteristics of capacitance charging and discharging. An analog digital signal converter having an amplification function as described in claim 2, wherein the capacitance value correction circuit further comprises: a correction capacitor, which accumulates capacitance error values in the capacitance-charge digital analog converter, and then adds Charge and discharge can be corrected to correct the charge and discharge levels caused by the error value; and a correction DAC circuit is used to convert the correction code into an analog voltage and then input to the correction capacitor, so that an accurate signal can be obtained.