KR101253224B1 - Analog digital converter - Google Patents

Abstract

The analog-to-digital converter may include a first voltage input unit configured to output a first voltage based on a first input voltage and a common voltage, and a second voltage based on a second input voltage and a common voltage differentially different from the first input voltage. A second sample input unit, a first sample hold unit performing a sample hold operation based on the first input voltage, the second input voltage, and the common voltage, based on the first input voltage, the second input voltage, and the common voltage. A second sample hold part for performing a sample hold operation, a first capacitor array selectively connected to an output terminal of the first sample hold part, and outputting a voltage charged to a plurality of capacitors connected in parallel; A second capacitor array selectively connected to an output terminal and outputting a voltage charged to a plurality of capacitors connected in parallel; the first voltage input unit, the second voltage input unit, According to a comparison result of a dual comparator and a sequential comparison algorithm comparing the output voltages of the first capacitor array and the second capacitor array and the comparison result of the double comparator, a digital code for an input voltage is generated, and the first sample hold part and the second sample part are generated. And a SAR control unit configured to transmit a feedback voltage to the sample hold unit and generate a control signal for controlling the operations of the first capacitor array and the second capacitor array.

Description

Analog-to-digital converter {ANALOG DIGITAL CONVERTER}

The present invention relates to an analog to digital converter with an improved structure.

Recently, as various portable devices are spread and various functions that the portable devices can perform, demand for low power consumption is increasing. To this end, a configuration of reducing driving voltages for driving various SoCs or processing devices included in portable devices is used. However, such a reduction in driving voltage inevitably degrades the analog circuit performance, thereby increasing the design difficulty. In particular, as the size of the turn-on resistance of a switching element such as a MOSFET is rapidly reduced, the gain of the operational amplifier is reduced, and the matching characteristics between the active element and the passive element are deteriorated, making it difficult to design an analog circuit. On the other hand, the operation speed of the digital circuit is faster, and at the same time, a design having a low power characteristic becomes possible. As a result, successive Approximation Register Analog to Digital Converters (SAR ADCs), which consist only of digital circuits, have been in the spotlight in comparison with pipeline analog-to-digital converters that include many analog circuits.

Analog-to-digital converters are indispensable for communication between humans and electronic devices and are used in almost all electronic devices. In particular, the sequential analog-to-digital converter is small in size and power consumption, making it suitable for portable electronic devices such as PMPs, mobile phones and laptops.

Meanwhile, in connection with the present invention, Korean Patent No. 193-0000486 (name of the invention: an analog / digital conversion device and a conversion method of a high-speed difference comparison method using pipelined parallel processing) has a number of low-bit digital / analog converters. A sequential comparison type analog / digital converting apparatus which performs pipelined parallel processing by employing a s.

In addition, Korean Laid-Open Patent Publication No. 2007-0030002 (name of the high-efficiency analog-to-digital converter) provides a SAR ADC which reduces the area occupied by a capacitor by remarkably reducing the number of capacitors by a charge redistribution method.

The present invention is to solve the above-mentioned problems of the prior art, and provides an analog-to-digital converter that can realize a small area and low power consumption by using the advantages of the configuration of the pipelined ADC and the ADC of the sequential comparison structure.

According to an aspect of the present invention, there is provided an analog-to-digital converter comprising: a first voltage input unit configured to output a first voltage based on a first input voltage and a common voltage; and a differential relationship with the first input voltage. A second voltage input unit configured to output a second voltage based on the second input voltage and the common voltage, a first sample hold unit performing a sample hold operation based on the first input voltage, the second input voltage, and the common voltage; A second sample hold part performing a sample hold operation based on the first input voltage, a second input voltage, and a common voltage, and selectively connected to an output terminal of the first sample hold part, and charged in a plurality of capacitors connected in parallel; A second capacitor array configured to output a voltage and a second capacitor selectively connected to an output terminal of the second sample-hold unit, and output a voltage charged to a plurality of capacitors connected in parallel According to the comparison result of the dual comparator and the sequential comparison algorithm and the dual comparator comparing the output voltage of the capacitor array, the first voltage input unit, the second voltage input unit, the first capacitor array and the second capacitor array, A SAR control unit for generating a digital code, transmitting a feedback voltage to the first sample holding unit and the second sample holding unit, and generating a control signal for controlling the operation of the first capacitor array and the second capacitor array. The dual comparator transfers a comparison result of the first voltage input unit and a second voltage input unit to the SAR controller, or transmits a comparison result of output voltages of the first capacitor array and the second capacitor array to the SAR controller. .

According to the above-described problem solving means of the present invention, by applying the algorithm of the pipeline analog-to-digital converter to the sequential analog-to-digital converter, the time to significantly reduce the size of the input capacitance, and at the same time to correct the offset voltage of the comparator Can be secured. Through this configuration, the influence of the offset error of the comparator on the entire analog-to-digital converter can be minimized. In addition, by taking a top-sampling scheme and applying a new low-power series charge redistribution digital-to-analog converter like the existing invention, the number of capacitors required at high resolution can be significantly reduced. In particular, one comparator is required in the pipeline structure and the sequential-comparative structure, whereas the structure of the present invention uses a dual-input comparator so that one comparator can be shared by two structures. The power required by the system can also be minimized.

1A and 1B are diagrams showing the configuration of a sequential analog-to-digital converter that is commonly used.
2A to 2C are diagrams illustrating the configuration and detailed operation of a SAR ADC device according to an embodiment of the present invention.
3 is a diagram illustrating a configuration of an amplifier included in a sample hold unit according to an embodiment of the present invention.
4 is a diagram illustrating a gain curve of a sample hold part according to an exemplary embodiment of the present invention.
5A is a diagram illustrating a detailed configuration of a DAC included in a capacitor array according to an embodiment of the present invention, and FIG. 5B is a diagram for describing an operation of the DAC.
6 is a diagram illustrating a configuration of a double comparison unit according to an embodiment of the present invention.
7 is a timing diagram for describing an operation of a dual comparator according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between . Also, when an element is referred to as "comprising ", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise.

1A and 1B are diagrams showing the configuration of a sequential analog-to-digital converter that is commonly used.

FIG. 1A shows a SAR ADC with 10-bit resolution, which has a differential structure and includes a capacitor array, a comparator 10, a SAR control circuit 12, and the like. The illustrated capacitor array functions as a sample hold circuit and a reference DAC capacitor.

For simplicity, the description is based on a positive capacitor array disposed on the upper side of the differential structure. In the sampling step, the first input voltage Vip is applied to the bottom plate of the capacitor, and the common voltage Vcm is applied to the top plate. Next, the reference voltage Vref is applied to the capacitor C1 having the largest capacitance, and the remaining capacitors are grounded. This operation is the same for the negative capacitor array. The comparator 10 compares the voltages of both capacitor arrays with the voltages of the negative capacitor arrays. If the first input voltage Vip is greater than the second input voltage Vin, the MSB is set to one. Otherwise, the MSB is set to zero and the capacitor with the largest capacitance is grounded. Next, the reference voltage Vref is applied to the second largest capacitor C2, and the remaining capacitors are grounded. Similarly, the value of the next bit is determined according to the comparison result of the comparator 10, and this operation is repeated to determine the bit value up to the LSB.

Unlike FIG. 1A, FIG. 1B applies a first input voltage Vip and a second input voltage Vin to a top plate of a capacitor, and reduces the number of capacitors included in the capacitor array. In this case, the input voltage is directly applied to the upper plate of the capacitor through the bootstrap switch 18. Meanwhile, the reference voltage Vref is applied to the lower plate of the capacitor. After turning off the bootstrap switch 18, a comparison operation is performed through the comparator 14, and the first capacitor C1 at the higher potential is grounded, but the first capacitor C1 at the other side is grounded. Vref) is maintained. This operation is repeated to determine bit values up to the LSB. As described above, in the case of the top sampling method in which an input voltage is directly input to the upper plate of the capacitor, the voltage connected to the lower plate of each capacitor is determined by the output of the comparator. This approach enables analog-to-digital converters of the same resolution with half the number of capacitors compared to conventional sequential-to-comparative analog-to-digital converters, but this also requires a large number of capacitors in high-resolution analog-to-digital converters.

2A to 2C are diagrams illustrating the configuration and detailed operation of a SAR ADC device according to an embodiment of the present invention.

The illustrated SAR ADC device 100 includes a first sample hold unit 110, a second sample hold unit 120, a first input selector 130, a second input selector 140, and a first capacitor array ( 150, a second capacitor array 160, a first voltage input unit 170, a second voltage input unit 180, a double comparator 190, and a SAR controller 200.

The first sample holding unit 110 is connected to a first input voltage Vinp, a second input voltage Vinn, or a common voltage Vcm input terminal to charge and discharge two capacitors Cs and a plurality of switching elements ( S111 ˜ S115) and an amplifier 112. The first sample hold unit 110 controls whether the switching elements S111 to S115 are turned on, samples an input voltage, and transmits a feedback voltage Vrefp or Vrefn transmitted from the SAR controller 200 according to a comparison result of the input voltages. Hold).

Referring to a specific operation, in the sampling step, the switching elements S111, S112, S113, and S114 are turned on, and the switching element S115 is turned off. Each input capacitor Cs is charged with a difference voltage between the first input voltage Vinp and the common voltage Vcm or a difference voltage between the second input voltage Vinn and the common voltage Vcm. Accordingly, there is an effect of minimizing the input capacitance to 2Cs.

Next, as shown in FIG. 2B, in the MSB comparison step, the switching device S115 is turned on, and the remaining switching devices S111, S112, S113, and S114 are turned off. At this time, as the switching element S115 is turned on, the input capacitance is converted from 2Cs to Cs.

Next, as shown in FIG. 2C, while the output of the dual comparator 190 is applied to the first sample hold unit 110, the output voltage of the first sample hold unit 110 is held.

 3 is a diagram illustrating a configuration of an amplifier included in a sample hold unit according to an embodiment of the present invention.

As shown, the switching element S300 selectively connects two NMOS transistors 310 and 312 and an NMOS transistor connected in series between a power supply voltage and a ground terminal. A bias voltage is applied to the upper NMOS transistor 310, and an input voltage Vin is applied to the lower NMOS transistor 312. At this time, the voltage applied to the connection node of the NMOS transistors 310 and 312 becomes the output voltage Vout. In the present invention, the amplifier 112 operates only in the holding step to minimize power consumption. That is, the turn-on time of the switching device S300 is adjusted to operate the amplifier 112 only in the holding step.

Referring back to FIG. 2, according to the configuration of the sample hold unit, an output voltage having a gain of 2 may be obtained as the input signal increases.

4 is a diagram illustrating a gain curve of a sample hold part according to an exemplary embodiment of the present invention.

As shown, an output voltage with a gain of 2 is obtained as the input signal is increased, thereby outputting a 1-bit MSB code.

Referring to FIG. 2 again, the configuration of the second sample holding part 120 is substantially the same as that of the first sample holding part 110. That is, the second sample hold unit 120 is connected to a first input voltage Vinp, a second input voltage Vinn, or a common voltage Vcm input terminal to charge and discharge two capacitors Cs and a plurality of switches. Elements S121 to S125 and an amplifier 12. The second sample hold unit 120 controls whether the switching elements S121 to S125 are turned on, samples the input voltage, and transmits the feedback voltage Vrefp or Vrefn transmitted from the SAR controller 200 according to the comparison result of the input voltages. Hold).

The first input selector 130 includes a switching element S132 connected to an output terminal of the first sample holding unit 110 and a switching element S134 connected to an output terminal of the common voltage Vcm. Accordingly, the output voltage or the common voltage Vcm of the first sample hold part 110 is transferred to the first capacitor array 150.

Similarly, the second input selector 140 includes switching elements S142 and S144. Accordingly, the output voltage or the common voltage Vcm of the second sample hold unit 120 is transferred to the second capacitor array 160.

The first voltage input unit 170 includes a capacitor Cc, a switching element S172 for selectively transferring an input voltage to the capacitor, and a switching element S174 for applying a common voltage to an output terminal of the capacitor Cc. At this time, one end of the capacitor Cc is connected to the switching element S172, and the other end is connected to the second both input terminals 2P of the dual comparator 190. The input voltage transferred through the switching element S172 may be a first input voltage Vin or a common voltage Vcm.

Similarly, the second voltage input unit 180 includes a capacitor Cc and switching elements S182 and S184. At this time, one end of the capacitor (Cc) is connected to the switching element (S182), the other end is connected to the second negative input terminal (2N) of the double comparator 190. The input voltage transmitted through the switching element S182 may be the second input voltage Vinn or the common voltage Vcm.

Meanwhile, the first input voltage Vinp and the second input voltage Vinn correspond to differential voltages, and the absolute value of the difference between the first input voltage Vinp and the common voltage and the second input voltage Vinn are common. The absolute value of the difference in voltages is the same.

The first capacitor array 150 is connected to the first input terminal 1P of the dual comparator 190 and the upper plate, and controls the plurality of capacitors C1 to C5 and the SAR controller 200 in parallel with each other. A plurality of switching elements (S151 ~ S155) for applying a reference voltage (Vrefp) to the lower plate of each capacitor according to the signal. In this case, the capacitances of the fourth capacitor C4 and the fifth capacitor C5 are the same, and the capacitance of the first capacitor C1 is eight times the capacitance of the fourth capacitor C4, and the second capacitor C2. The capacitance of is configured to be four times the capacity of the fourth capacitor (C4), the capacity of the third capacitor (C3) is configured to be twice the capacity of the fourth capacitor (C4).

Meanwhile, in the present invention, the DAC 152 is selectively connected to the fifth capacitor C5 to reduce the number of capacitors included in the capacitor array.

For example, in the case of configuring a 10-bit ADC, according to the embodiment of FIG. 1A, 2 ^ 10 (10 powers of 2) unit capacitors are used for the upper capacitor array, and according to the embodiment of FIG. 1B, the upper capacitor array Use 2 ^ 9 unit capacitors. However, according to the present invention, it is possible to include only 2 ^ 4 (fourth power of two) unit capacitors in the upper capacitor array by connecting 4-bit DACs, thereby significantly reducing the total number of capacitors.

Similarly, the second capacitor array 160 includes a plurality of capacitors C1 to C5 and a plurality of switching elements S161 to S165 connected to the first negative input terminal 1N of the dual comparator 190. In addition, the DAC 162 is selectively connected to the fifth capacitor C5, thereby reducing the number of capacitors included in the capacitor array.

A detailed configuration of the DACs 152 and 162 included in each capacitor array will be described.

5A is a diagram illustrating a detailed configuration of a DAC included in a capacitor array according to an embodiment of the present invention, and FIG. 5B is a diagram for describing an operation of the DAC.

The DAC 150 selectively applies the first and second capacitors C1 and C2, the first reference voltage REFP, the second reference voltage REFN or the common voltage Vcm to the respective capacitors C1 and C2. It includes a plurality of switching elements (S510 ~ S518) to be applied.

The first to third switching elements S510 to S516 charge the first capacitor C1 with the first reference voltage REFP, the second reference voltage REFN, or the common voltage Vcm. The fourth switching device S516 selectively connects the first capacitor C1 and the second capacitor C2 to redistribute the charges stored in each capacitor. The fifth switching element S518 charges the first reference voltage REFP to the second capacitor C2. That is, the process of distributing charge by repeating a process of applying a specific voltage to the first capacitor C1 and connecting the first capacitor C1 and the second capacitor C2 a predetermined number of times or more, after the first capacitor ( The voltage charged in C1) or the second capacitor C2 is used as the output voltage. In this case, various output voltages may be set according to the type of voltage connected to the first capacitor C1 and the number of times of repeating the above process.

Referring to FIG. 5B, it can be seen that a total of 16 output voltages are generated by performing the process of charging the first capacitor C1 four times and the process of redistributing the charge three times. At this time, there are five kinds of voltages connected to the first capacitor C1. That is, the first reference voltage (REFP), the second reference voltage (REFN), the common voltage (Vcm), the average of the first reference voltage (REFP) and the common voltage (Vcm), the second reference voltage (REFN) and the common voltage The voltage corresponding to the average of (Vcm) is connected. In this case, a separate voltage source may be added to provide a voltage corresponding to the average, but in the present invention, the first to third switching elements S510 to S514 may be configured as bootstrap switches to achieve the same effect. have. Bootstrap switch is a switch that always has a constant turn-on resistance regardless of the input voltage.If you want to apply the average voltage of two different voltages, the bootstrap switch is turned on at the same time by turning on two switching elements connected to each terminal of each voltage. The average voltage of the voltage can be output. That is, the first switching element S510 and the second switching element S512 are turned on simultaneously to apply a voltage corresponding to the average of the first reference voltage REFP and the common voltage Vcm to the first capacitor C1. . In addition, the second switching element S512 and the third switching element S514 are turned on at the same time to apply a voltage corresponding to the average of the second reference voltage REFN and the common voltage Vcm to the first capacitor C1. .

The dual comparator 190 may include a first bilateral input 1P, a second sample hold part 120, and a second capacitor array 160 output through the first sample hold part 110 and the first capacitor array 150. Receives the first negative input (1N), the second positive input (2P) output from the first voltage input unit 170 and the second negative input (2N) output from the second voltage input unit 180 output through To perform the comparison operation.

In particular, when each of the sample holding units 110 and 120 performs a sample holding operation, the input signals through the first bilateral input 1P and the first negative input 1N are compared, and the SAR controller 200 operates. In this case, the input signals through the second two-side input 2P and the second negative input 2N are compared. With this configuration, it is possible to minimize the time consumed by switching between the comparator and the capacitor array, and in particular, one comparator can be shared in the pipelined structure and the SAR structure.

The detailed configuration of the dual comparator 190 will be described.

6 is a diagram illustrating a configuration of a double comparison unit according to an embodiment of the present invention.

The dual comparator 190 receives a first bilateral input 1P, a first negative input 1N, a second bilateral input 2P, and a second negative input 2N to perform an amplification operation. 192, a comparator 194 that compares the magnitude of the output signal of the dual input amplifier 192.

The dual input amplifier 192 includes first to fifth switching elements P191, P193, N195, N197, and S199 connected between a power supply terminal VDD and a GND terminal. One terminal of the first switching device P191 is connected to the power supply terminal VDD, the first output terminal OUTP is connected to the other terminal, and the second both inputs 2P and the gate are connected to each other. The second switching element P193 has one terminal connected to the power supply terminal VDD, a second output terminal OUTN connected to the other terminal, and a gate connected to the second negative input 2N. The third switching element N195 has one terminal connected to the GND terminal, a first output terminal OUTP connected to the other terminal, and a gate connected to the first both inputs 1P. In the fourth switching device N197, one terminal is connected to the GND terminal, the second output terminal OUTN is connected to the other terminal, and the first negative input 1N is connected to the gate.

On the other hand, it includes a fifth switching element (S199) for selectively connecting the first output terminal (OUTP) and the second output terminal (OUTN).

According to such a configuration, if the first two-side input 1P and the first negative input 1N are the same, this functions only as a bias voltage and does not affect the output of the double comparator 190, and the second Only the two inputs 2P and the second negative input 2N are compared and output. Similarly, when the second two-sided input 2P and the second negative-side input 2N are the same, only the first two-sided input 1P and the first negative-side input 1N are compared and output.

On the other hand, when the fifth switching device S199 is turned on, the voltages of the first output terminal OUTP and the second output terminal OUTN become equal, and selectively reset the dual input amplifier 192 according to this operation. When performing the comparison operation for each bit, it is a considerable burden to reversely amplify the voltage which has already been amplified and the difference is reversed at the next input signal, and thus performs a reset operation to prevent this.

7 is a timing diagram for describing an operation of a dual comparator according to an embodiment of the present invention.

First, the input signal is amplified during the period in which the dual input amplifier 192 is active, and based on the result of comparing the amplified value through the comparator 194, the SAR controller 200 determines that MSB-n (n is 1 or more). Natural number) In this case, the second input amplifier 192 is reset by using the fifth switching device S199 to perform the comparison operation on the next bit. That is, the reset operation is performed once each time the amplification and comparison operations are completed.

Referring now to Figures 2a to 2c, the overall operation will be described.

In the sampling step, the switching elements S111, S112, S113, and S114 of the first sample hold part 110 are turned on, and the switching element S115 is turned off. Similarly, the switching elements S121, S122, S123, and S124 of the second sample hold part 120 are turned on, and the switching element S125 is turned off. Accordingly, each input capacitor Cs is charged with a difference voltage between the first input voltage Vinp and the common voltage Vcm or a difference voltage between the second input voltage Vinn and the common voltage Vcm.

In addition, a calibration operation is performed on the dual comparator 190. With the same voltage (Vcm) applied to all inputs of the double comparator 190, the output result of the double comparator 190 is viewed, and the dual comparator 190 is minimized so that the offset voltage is minimum. Perform a correction operation on the

To this end, the common voltage Vcm is applied to the second both input terminals 2P and the second negative input terminal 2N through the first input selector 130 and the second input selector 140. In addition, the common voltage Vcm is applied to the first bilateral input terminal 1P and the first negative input terminal 1N through the first voltage input unit 170 and the second voltage input unit 180.

Subsequently, as shown in FIG. 2B, in the MSB comparison step, the first voltage 2Vcm-Vinp and the second voltage 2Vcm-Vinn are respectively set by the first voltage input unit 170 and the second voltage input unit 180. 1 are applied to both input terminals 1P and the first negative input terminal 1N.

Meanwhile, the switching device S115 of the first sample hold unit 110 is turned on, and the remaining switching devices S111, S112, S113, and S114 are turned off to activate the operation of the amplifier 112. In addition, the switching element S125 of the second sample hold unit 120 is turned on, and the remaining switching elements S121, S122, S123, and S124 are turned off. Accordingly, the common voltage Vcm is equally applied to the second positive input terminal 2P and the second negative input terminal 1N. According to this operation, the dual input comparator 190 performs a comparison operation based only on the voltages input to the first two input terminals 1P and the first negative input terminal 1N.

The SAR controller 200 generates an MSB code according to a comparison result of the voltage signals inputted to the first two input terminals 1P and the first negative input terminal 1N of the dual comparator 190. In this case, when the first input voltage Vinp is greater than the second input voltage Vinn, MSB = 1 is set, the first feedback voltage Vrefp is transmitted to the first sample holding unit 110, and the second The second feedback voltage Vrefn is transferred to the sample hold unit 120. However, when the first input voltage Vinp is smaller than the second input voltage Vinn, MSB = 0 is set, the second feedback voltage Vrefn is transmitted to the first sample holding unit 110, and the second The first feedback voltage Vrefp is transferred to the sample hold unit 120.

Next, as shown in FIG. 2C, the MSB-1 code is generated according to the voltage held by each sample holding unit 110 or 120. First, the common voltage Vcm is applied to the first bilateral input terminal 1P and the first negative input terminal 1N through the first voltage input unit 170 and the second voltage input unit 180. Accordingly, the comparison operation is performed according to the voltage applied to the second positive input terminal 2P and the second negative input terminal 2N.

Meanwhile, the switching element S132 of the first input selector 130 is turned on and the switching element S134 is turned off, so that the output voltage of the first sample hold unit 110 is applied to the first both input terminals 1P. To be authorized. Similarly, the switching element S142 of the second input selection unit 140 is turned on and the switching element S144 is turned off, so that the output voltage of the second sample holding unit 120 is applied to the first negative input terminal 1N. To be authorized.

Accordingly, the first voltage 2Vi + Vrefp or 2Vi + Vrefn is input to the second both input terminals 2p, and the second voltage (-2Vi + Vrefn or -2Vi + Vrefp) is input to the second negative input terminal 2N. Can be entered. In this case, the voltage Vi is an absolute value of the difference between the first input voltage Vin and the common voltage or an absolute value of the difference between the second input voltage Vin and the common voltage.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is shown by the following claims rather than the above description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

110: first sample hold part 120: second sample hold part
130: first input selector 140: second input selector
150: first capacitor array 160: second capacitor array
170: first voltage input unit 180: second voltage input unit
190: dual input comparison unit 200: SAR control unit

Claims (8)

In the analog-to-digital converter,
A first voltage input unit configured to output a first voltage based on the first input voltage and the common voltage;
A second voltage input unit configured to output a second voltage based on a second input voltage and a common voltage that are differentially associated with the first input voltage;
A first sample hold part performing a sample hold operation based on the first input voltage, the second input voltage, and the common voltage;
A second sample hold unit performing a sample hold operation based on the first input voltage, the second input voltage, and the common voltage;
A first capacitor array selectively connected to an output terminal of the first sample holding unit and outputting a voltage charged in a plurality of capacitors connected in parallel;
A second capacitor array selectively connected to an output terminal of the second sample holding unit and outputting a voltage charged in a plurality of capacitors connected in parallel;
A dual comparator for comparing output voltages of the first voltage input part, the second voltage input part, the first capacitor array, and the second capacitor array;
According to a sequential comparison algorithm and a comparison result of the double comparator, a digital code for an input voltage is generated, a feedback voltage is transmitted to the first sample hold unit and the second sample hold unit, and the first capacitor array and the second Including a SAR control unit for generating a control signal for controlling the operation of the capacitor array,
The dual comparator transfers a comparison result of the first voltage input unit and a second voltage input unit to the SAR controller, or transmits a comparison result of output voltages of the first capacitor array and the second capacitor array to the SAR controller.
Analog to digital converter. The method of claim 1,
When the feedback voltage is transmitted, the first sample hold unit replaces the second input voltage with the feedback voltage to perform a sample hold operation.
When the feedback voltage is transmitted, the second sample hold part replaces the first input voltage with the feedback voltage to perform a sample hold operation.
Analog to digital converter. The method of claim 1,
The first sample hold unit,
A first capacitor charged and discharged according to the first input voltage and a common voltage
A second capacitor charged and discharged according to the second input voltage and the common voltage,
A first switching element for selectively connecting the first capacitor and the second capacitor;
A first amplifier connected to one end of the first capacitor,
The first amplifier amplifies and outputs the voltage charged in the first capacitor and the second capacitor according to the operation of the first switching element,
The second sample hold unit,
A first capacitor charged and discharged according to the second input voltage and the common voltage
A second capacitor charged and discharged according to the first input voltage and a common voltage,
A second switching element for selectively connecting the first capacitor and the second capacitor;
A second amplifier connected to one end of the first capacitor,
The second amplifier amplifies and outputs the voltage charged in the first capacitor and the second capacitor according to the operation of the second switching element.
Analog to digital converter. The method of claim 1,
A first input selector configured to selectively transfer an output voltage or a common voltage of the first sample hold unit to the first capacitor array;
And a second input selector for selectively transferring the output voltage or the common voltage of the second sample hold unit to the second capacitor array. The method of claim 1,
The first voltage input unit
First capacitor,
A first switching element connected to one end of the first capacitor and applying the first input voltage or a common voltage;
A second switching element connected to the other terminal of the first capacitor and applying a common voltage,
The second voltage input unit
Second capacitor,
A first switching element connected to one end of the second capacitor to apply the second input voltage or common voltage;
And a second switching element connected to the other terminal of the second capacitor and applying a common voltage. The method of claim 1,
The first capacitor array is
First to fifth capacitors connected to the first both side input terminals of the dual comparator and the upper plate and in parallel with each other;
Including the first to fifth switching element for applying a reference voltage to the lower plate of each capacitor in accordance with the control signal of the SAR control unit,
The capacity of the fourth capacitor and the fifth capacitor are configured the same,
The capacity of the first capacitor is configured to be eight times the capacity of the fourth capacitor,
The capacity of the second capacitor is configured to be four times the capacity of the fourth capacitor,
The capacity of the third capacitor is configured to be twice the capacity of the fourth capacitor,
A first digital-to-analog converter selectively connected to the fifth switching element to transfer a plurality of levels of reference voltages to the fifth capacitor,
The second capacitor array
The sixth to tenth capacitors connected to the first negative input terminal and the upper plate of the dual comparator and being in parallel with each other;
6 to 10 th switching elements for applying a reference voltage to the lower plate of each capacitor according to the control signal of the SAR control unit,
The capacitances of the ninth capacitor and the tenth capacitor are the same,
The capacity of the sixth capacitor is configured to be eight times the capacity of the ninth capacitor,
The capacity of the seventh capacitor is configured to be four times the capacity of the ninth capacitor,
The capacitance of the eighth capacitor is configured to be twice the capacitance of the ninth capacitor,
And a second digital analog converter selectively connected to the tenth switching element to transfer a plurality of levels of reference voltages to the tenth capacitor. The method according to claim 6,
The first and second digital to analog converter,
A first capacitor in which a first reference voltage, a common voltage and a second reference voltage are selectively applied to one terminal and a second reference voltage is applied to the other terminal,
A second capacitor to which a voltage of one terminal of the first capacitor and the first reference voltage are selectively applied to one terminal, and the other terminal and the other terminal of the first capacitor are connected;
First to third switching elements configured to apply a first reference voltage, a common voltage, and a second reference voltage to the first capacitor,
A fourth switching element for selectively coupling one end of the first capacitor and one end of the second capacitor;
A fifth switching element for selectively applying the first reference voltage to one terminal of the second capacitor,
Wherein said first to third switching elements comprise a bootstrap switch. The method of claim 1,
The double comparison unit,
A dual input amplifier configured to perform an amplification operation based on output voltages of the first voltage input unit, the second voltage input unit, the first capacitor array, and the second capacitor array;
Comparators for comparing the output voltage of the dual input amplifier,
When the outputs of the first voltage input unit and the second voltage input unit are the same, the output voltages of the first capacitor array and the second capacitor array are compared.
And comparing the output voltages of the first voltage input unit and the second voltage input unit when the output voltage of the first capacitor array and the output voltage of the second capacitor array are the same.

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