KR101062724B1 - Analog / Digital Converter - Google Patents

Abstract

The present invention relates to an analog-to-digital converter for converting an analog signal into a digital signal, and more particularly, to an analog-to-digital converter that generates N-bit digitized output signals with only N comparators.

An N-bit analog-to-digital converter composed of N converters according to an embodiment of the present invention, wherein each converter comprises: a comparator for receiving and comparing one voltage and a second voltage; And a second voltage generator configured to generate the second voltage. The second voltage generator is a constant current source having a constant current amount; And a resistor unit for receiving the constant current source, wherein the first voltage is a constant voltage and the second voltage is determined by a resistance of the resistor unit. The resistor unit provided in the arbitrary i-th (i is an integer of 1,2,3 .... i) conversion unit is 2 ^Ni R, 2 ^{N- (i-1)} R, connected in series between a constant current source and ground, 2 ^{N- (i-2)} R, ..., resistance of 2 ^{N- {i- (i-1)} R; I-1 switches connected in parallel with each resistor from the resistor adjacent to the ground, and the output signal of the comparator provided in the arbitrary i-th converter is i + 1, i + 2, ... N-th converter. It is commonly received from the constant current source provided in the i-th switch in the adjacent order. The positive terminal of each comparator receives the first voltage and the negative terminal of each comparator receives the second voltage. The second voltage generator is configured to adjust the resistance ratio by turning on / off the switch according to a signal received by each switch, and generates a second voltage through a resistance value and a constant current source controlled by the operation of the switch, and the constant current The circles all analogue digital converter characterized in that the same current value.

Description

Analog to Digital Converters {Analog to Digital Converter}

1 illustrates a basic N-bit parallel analog-to-digital converter circuit constructed in the prior art method.

2 shows a 3-bit analog-to-digital converter circuit in accordance with the present invention.

3 illustrates an N-bit analog-to-digital converter circuit in accordance with the present invention.

4 is a diagram illustrating an output according to a first voltage level of FIG. 2;

  -Explanation of symbols for the main parts of the drawing-

Diff1 ~ DiffN: Comparator

I1 ~ In: Constant current source

201, 211, 221, 320: second voltage generator

       The present invention relates to an analog-to-digital converter for converting an analog signal into a digital signal, and more particularly, to an analog-to-digital converter that generates N-bit digitized output signal with only N comparators.

       Hereinafter, an example of a conventional digital-to-analog converter will be described with reference to the drawings.

As shown in FIG. 1, the analog-to-digital converter includes a comparator unit 110 composed of 2 ^N comparators for receiving and comparing a first voltage ViN and a second voltage, which are constant voltages, and a reference voltage and a ground for generating a second voltage. One encoder (2 ^N to N ENcorder) 121 which receives the output signals of the second voltage generator 100 and the comparator unit 110 including 2 ^N +1 resistors arranged in series and outputs a digital output signal. It includes an encoding unit 120 including a).

        In the operation of the conventional analog-to-digital converter shown in FIG. 1, the second voltage generator generates a divided voltage by an angular resistor configured in series between the reference voltage Vref and ground, and generates a node between the resistor and the resistor. Pass through each comparator.

The generated divided voltages (V1, V2 ... V2 ⁿ : second voltage) are received at the negative input terminal of each comparator, and compare the potential difference with the first voltage received at the positive input terminal to generate an output signal.

        The encoder receives the output signal of each comparator and generates an N-bit digitized output signal through an encryption process.

As can be seen above, conventional analog-to-digital converters use 2 ^N comparators to output N-bit digital output signals.

Therefore, in the related art, as the number of bits increases, the number of comparators also increases by 2 ^N at the same time, which has a problem that is contrary to the trend of higher directing semiconductor devices.

SUMMARY OF THE INVENTION The present invention has been proposed to solve the above problems, and proposes an analog-to-digital converter that generates N-bit digital output signals using N comparators, thereby enabling fast operation of analog-to-digital conversion with a small layout. to digital converting).

An N-bit analog-to-digital converter composed of N converters according to an embodiment of the present invention, wherein each converter comprises: a comparator for receiving and comparing one voltage and a second voltage; And a second voltage generator configured to generate the second voltage. The second voltage generator is a constant current source having a constant current amount; And a resistor unit for receiving the constant current source, wherein the first voltage is a constant voltage and the second voltage is determined by a resistance of the resistor unit. The resistor unit provided in the arbitrary i-th (i is an integer of 1, 2, 3, ... i) conversion unit 2 ^Ni R, 2 ^{N- (i-1)} R, connected in series between the constant current source and ground, 2 ^{N- (i-2)} R, ..., resistance of 2 ^{N- {i- (i-1)} R; I-1 switches connected in parallel with each resistor from the resistor adjacent to the ground, and the output signal of the comparator provided in the arbitrary i-th converter is i + 1, i + 2, ... N-th converter. It is commonly received from the constant current source provided in the i-th switch in the adjacent order. The positive terminal of each comparator receives the first voltage, and the negative terminal of each comparator receives the second voltage. The second voltage generator is configured to adjust the resistance ratio by turning on / off the switch according to a signal received by each switch, and generates a second voltage through a resistance value and a constant current source controlled by the operation of the switch, and the constant current The circles all analogue digital converter characterized in that the same current value.

(Example)

     Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

     3 illustrates an N-bit analog-to-digital converter circuit in accordance with the present invention.

     The analog-to-digital converter of the present invention is composed of N converters for outputting N-bit digital output signals.

     Each converter includes a comparator Diffn for receiving and comparing the first voltage Vin and the second voltage Vn as a positive terminal and a negative terminal, respectively, and a second voltage generator 301 for generating the second voltage.

     The second voltage generator 301 includes a resistor 302 for receiving a constant current source In and a constant current source In having the same amount of current, and the resistor unit 302 includes a constant current source In and a ground ( VSS) consists of a plurality of switches that can adjust the resistance ratio and a plurality of resistors connected in series.

     The junction terminal of the constant current source In and the resistor unit 302 is connected to the negative terminal of the comparator Diffn to transfer the generated second voltage Vn to the comparator.                     

      As shown, the constant voltage Vin of the memory device is represented by the first voltage, and the reference voltages V1, V2, ... Vn received by the comparator are represented by the second voltage.

In Fig. 3, any i-th (i is an integer of 1,2,3 ... i) converter 310 is connected to a constant current source Ii and ground in series with 2 ^Ni , 2 ^{N- (i- 1)} , 2 ^{N- (i-2)} , .... 2 includes a resistor portion 311 comprising an resistor having an integer multiple of ^{N- {i- (i-1)}} and i-1 switches connected in parallel with each resistor from a resistor adjacent to ground.

      The output signal outi of any i-th converter through the comparator Diffi is common to the i-th switch in the adjacent order from the constant current source provided in the i + 1, i + 2, ..., N-th converter. Is received.

     2 illustrates an analog-to-digital converter circuit for generating a 3-bit digitized output signal.

     Hereinafter, an embodiment of a 3-bit analog-to-digital converter will be described with reference to FIG. 2.

     As shown in FIG. 2, the analog-to-digital converter receives and compares the first voltage Vin and the second voltages V1, V2, and V3 to output the 3-bit output signals out1, out2, and out3, respectively. Three converters 200, 210, and 220 including comparators Diff1, Diff2, and Diff3 and second voltage generators 201, 211, and 221 are provided.

      In operation, the first voltage Vin is commonly received to each of the comparators Diff1, Diff2, and Diff3, and each of the comparators Diff1, Diff2, and Diff3 is received from the first voltage Vin and the second voltage. When the levels of the second voltages V1, V2, and V3 are high by comparing the voltage levels of V1, V2, and V3, the high level output signals out1, out2, and out3 are output. When the level of Vin is high, the low level output signals out1, out2, and out3 are output.

      The same current value is applied to the constant current sources I1, I2, and I3 of each conversion section, and a voltage level of greater than 6 times and less than 7 times the second voltage I * R is applied to the first voltage Vin. In this case, since the voltage level 6R * I to 7R * I of the first voltage Vin received by the comparator Diff1 is higher than the second voltage 4R * I: V1, the output of the comparator Diff1 is output. Make (out1) high level. The output signal is received by the switch SW1 of the converter 210 and the switch SW2 of the converter 220.

      The received output signal out1 turns off the switches SW1 and SW2 to make the resistance of the converter 210 6R. Accordingly, the level of the second voltage V2 generated by the second voltage generator 211 becomes 6R * I and is received by the negative input terminal of the comparator Diff2.

      The comparator Diff2 outputs the high level output signal out2 at a first voltage Vin level higher than the received second voltage level V2, and the output signal out2 is provided in the converter 220. The switch SW3 is turned off to set the resistance of the converter 220 to 7R. Accordingly, the level of the second voltage V3 becomes 7R * I, and the comparator outputs the low level output signal out3 because the level of the second voltage V3 is higher than that of the received first voltage Vin level.

      In this series of operations, the 3-bit analog-to-digital converter generates digital output signals out1 = 1, out2 = 1, out3 = 0.

      4 is a table illustrating an operation of a circuit according to a first voltage Vin level in the 3-bit analog-to-digital converter of FIG. 2.

      As can be seen in Figure 4, Figure 2 is a circuit that can obtain a digital output of the appropriate three bits according to the first voltage (Vin) level, the three comparators (Diff1, Diff2, Diff3) used is enough digitization It can be seen that.

      Next, after examining the difference between the conventional circuit and the circuit of the present invention, the superiority of the circuit of the present invention will be described.

First, the conventional circuit shown in FIG. 1 uses 2 ^N comparators to output N-bit digital output signals, whereas the circuit of the present invention shown in FIGS. 2 and 3 uses only N comparators. It became.

      In addition, in Fig. 1, the output of each comparator is used to implement a digital signal, whereas in the present invention, a digital signal can be implemented by changing a resistance ratio according to a separate constant current source and a switch operation without using an encoder. Do.

      Due to this difference, the circuit of the present invention has an advantage that the circuit can be configured with a sufficiently small size in design.

As can be seen from the above, in the case of using the analog-to-digital converter according to the present invention, it is possible to implement a circuit in a small size when designing. The analog-to-digital converter of the present invention can be applied to a semiconductor memory that requires high serialization.

Claims (5)

      In the N-bit analog-to-digital converter composed of N conversion units,       Each conversion unit       A comparator for receiving and comparing the first voltage and the second voltage;       A second voltage generator configured to generate the second voltage;       The second voltage generator       Constant current sources having the same amount of current;       It includes a resistor for receiving the constant current source,       The first voltage is a constant voltage, the second voltage is determined by the resistance of the resistor unit,       At least one of the N converters changes the resistance of the resistor according to an output of the comparator provided by the other converter.        Claim 2 has been abandoned due to the setting registration fee.        The method of claim 1,        The resistor unit provided in the arbitrary i-th conversion unit (i is an integer of 1,2,3 ... i) 2 ^Ni R, 2 ^{N- (i-1)} R, 2 ^{N- (i-2)} R, connected in series between a constant current source and ground, ..., resistance of 2 ^{N- {i- (i-1)} R;        And an i-1 switch connected in parallel with each resistor from a resistor adjacent to the ground.        Claim 3 was abandoned when the setup registration fee was paid.        3. The method of claim 2,        The output signal of the comparator provided in the arbitrary i-th converter is commonly received from the constant current source provided in i + 1, i + 2, ... N-th converter by the i-th switch in the adjacent order. Analog / digital converter.        Claim 4 was abandoned when the registration fee was paid.        3. The method of claim 2,        A positive terminal of the comparator receives the first voltage,        And the negative terminal of the comparator receives the second voltage.        Claim 5 was abandoned upon payment of a set-up fee.        The method of claim 2 or 3,        The second voltage generator        In accordance with the signal received by each switch to turn on / off the switch to adjust the resistance ratio,        The second voltage is generated through the resistance value and the constant current source adjusted by the operation of the switch,        And said constant current sources all have the same current value.

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