High-precision digital-to-analog converter and electronic equipment

Abstract

The invention provides a high-precision digital-to-analog converter and electronic equipment, and in the high-precision digital-to-analog converter, one end of a first terminating resistor is connected with a grounding end; the first end of the second terminating resistor is connected with the other end of the first terminating resistor, and the second end of the second terminating resistor is connected with the reference voltage source; the first end of the first control resistor is connected with the second end of the second terminating resistor through one inter-ladder resistor, the first end of each control resistor is connected with the first end of the other adjacent control resistor through one inter-ladder resistor, and the second end of each control resistor is connected with a grounding end or a reference voltage source through a switch; a first end of the voltage stabilizing capacitor is connected with a first end of the last control resistor, a second end of the voltage stabilizing capacitor is grounded, and the first end of the voltage stabilizing capacitor is a voltage output end of the high-precision digital-to-analog converter; wherein a voltage signal of the reference voltage source and a preset pulse modulation signal are synthesized into a modulation voltage.

Description

Technical Field

[0001] The present application relates to the technical field of integrated circuits, and in particular to a high-precision digital-to-analog converter and an electronic device. Background Art

[0002] At present, DAC (Digital to Analog Converter) is an indispensable bridge for communication between digital circuits and analog circuits, and has many applications in display technology and signal transmission. As the accuracy of DAC increases, the area grows exponentially. Too large an area will not only cause gradient errors inside the DAC, but also significantly increase the cost of the chip. Summary of the invention

[0003] The present application provides a high-precision digital-to-analog converter and an electronic device, which are used to reduce the area of ​​DAC while improving the DAC accuracy.

[0004] In a first aspect, an embodiment of the present application provides a high-precision digital-to-analog converter, the high-precision digital-to-analog converter comprising: A first terminating resistor, one end of which is connected to the ground terminal; a second termination resistor, wherein a first end of the second termination resistor is connected to the other end of the first termination resistor, and a second end of the second termination resistor is connected to a reference voltage source; Ladder resistance; Control resistors, wherein the first end of the first control resistor is connected to the second end of the second terminal resistor through one of the ladder resistors, the first end of each of the control resistors is connected to the first end of another adjacent control resistor through one of the ladder resistors, and the second ends of the control resistors are connected to the ground terminal or the reference voltage source through a switch; A voltage stabilizing capacitor, wherein a first end of the voltage stabilizing capacitor is connected to a first end of the last control resistor, a second end of the voltage stabilizing capacitor is grounded, and the first end of the voltage stabilizing capacitor is a voltage output end of the high-precision digital-to-analog converter; The reference voltage source is connected to a preset signal terminal, the preset signal terminal is used to transmit a pulse modulation signal, and the voltage signal of the reference voltage source and the pulse modulation signal are combined to form a modulation voltage.

[0005] In some embodiments, the high-precision digital-to-analog converter further includes: A control unit, the control unit is used to generate digital control data according to an input control instruction, and the digital control data is used to adjust the switch corresponding to the control resistor; the control unit is connected to the preset signal terminal and is also used to generate the pulse modulation signal according to a preset duty cycle.

[0006] In some embodiments, the preset signal terminal is connected to an external signal generating unit, and the signal generating unit is used to generate the pulse modulation signal according to a preset duty cycle.

[0007] In some embodiments, the duty cycle ranges from 0 to 1.

[0008] In a second aspect, an embodiment of the present application provides an electronic device, comprising a high-precision digital-to-analog converter as described in any one of the embodiments of the present application.

[0009] An embodiment of the present application provides a high-precision digital-to-analog converter, which includes: a first termination resistor, a second termination resistor, a ladder resistor, a control resistor and a voltage-stabilizing capacitor, wherein one end of the first termination resistor is connected to the ground terminal; the first end of the second termination resistor is connected to the other end of the first termination resistor, and the second end of the second termination resistor is connected to a reference voltage source; the first end of the first control resistor is connected to the second end of the second termination resistor through a ladder resistor, the first end of each control resistor is connected to the first end of another adjacent control resistor through a ladder resistor, and the second ends of the control resistors are connected to the ground terminal or to the reference voltage source through a switch; the first end of the voltage-stabilizing capacitor is connected to the first end of the last control resistor, the second end of the voltage-stabilizing capacitor is grounded, and the first end of the voltage-stabilizing capacitor is the voltage output end of the high-precision digital-to-analog converter; wherein the reference voltage source is connected to a preset signal end, the preset signal end is used to transmit a pulse modulation signal, and the voltage signal of the reference voltage source and the pulse modulation signal synthesize a modulation voltage. In the above-mentioned high-precision digital-to-analog converter, by adding a pulse modulation signal and a voltage-stabilizing capacitor at the voltage output end, the output signal of the high-precision digital-to-analog converter is adjusted between ±0.5 LSB (Least Significant Bit). If the pulse modulation signal is fine enough, the error of the output voltage of the high-precision converter can be infinitely small. Compared with the traditional full-speed adjustment digital-to-analog converter, not only the accuracy of the output voltage is improved, but also only a second termination resistor and a voltage-stabilizing capacitor are added, thereby reducing the increase in area. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0011] Figure 1 A circuit diagram of an original four-bit digital-to-analog converter provided in an embodiment of the present application; Figure 2A circuit diagram of a first type of four-digital-to-analog converter with gear adjustment provided in an embodiment of the present application; Figure 3 A schematic diagram of a first-order Thevenin equivalent circuit of a four-digit digital-to-analog converter with a first gear adjustment provided in an embodiment of the present application; Figure 4 A circuit diagram of a second four-digital-to-analog converter with gear adjustment provided in an embodiment of the present application; Figure 5 A truth table diagram of a second type of four-digital-to-analog converter for gear adjustment provided in an embodiment of the present application; Figure 6 A circuit diagram of a high-precision digital-to-analog converter provided in an embodiment of the present application; Figure 7 Schematic diagram of output voltage waveforms of various digital-to-analog converters provided in embodiments of the present application; Figure 8 Schematic diagram of partial waveforms of output voltages of two digital-to-analog converters provided in embodiments of the present application. DETAILED DESCRIPTION

[0012] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0013] The flowcharts shown in the accompanying drawings are only examples and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may also be decomposed, combined or partially merged, so the actual execution order may change according to actual conditions.

[0014] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0015] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0016] See also Figure 1 , Figure 1 This is a circuit diagram of an original four-bit digital-to-analog converter provided in an embodiment of the present application.

[0017] Since the potentials selected by all switches of the pure binary code-controlled DAC are completely opposite between 011...1 and 100...0, except for the terminating resistor fixed to GND, the rest are connected to V REF The control resistance of GND is opposite, and the error introduced by the control resistance is opposite and approximately equal in these two gears. At the same time, the variance of INL is the largest when the digital-to-analog converter is in the middle gear. The INL of 011...1 and 100...0 is the INL of the resistance ladder. Since these two gears are adjacent and opposite, the DNL here will also be larger.

[0018] In order to achieve higher precision in a smaller area, gear (control position) adjustment is often used.

[0019] See also Figure 2 , Figure 2 1 is a circuit diagram of a first type of four-bit digital-to-analog converter with gear adjustment provided in an embodiment of the present application. Figure 2 As shown, taking a four-bit D / A converter as an example, the single stage of the four-bit D / A converter is adjusted as shown in the figure, and the highest bit control resistor (2R) is changed to two branches of the first highest bit control resistor (3R) and the first highest bit control resistor (6R), and the original The split is and .

[0020] It should be noted that, in the embodiments of the present application, R can be regarded as a unit resistor, or as the resistance value of a unit resistor.

[0021] See also Figure 3 , Figure 3 1 is a schematic diagram of a first Thevenin equivalent circuit of a four-bit digital-to-analog converter with a first gear adjustment provided in an embodiment of the present application. Figure 3 As shown, the Thevenin equivalent of the low-order control resistor of the four-bit D / A converter with the first gear adjustment can be obtained: ; ; Among them, B is the decimal format of the current gear, that is, , where i is the gear position in the B zone equivalent to Thevenin, and N is the number of levels used for adjustment, with N = 4 at present. According to the above formula, if equivalent to b0, the value of B is the decimal number of b0; if equivalent to b1, the value of B is the decimal number of b1b0. At the same time, and The following conditions should be met: ; From this, the resistance value of the resistor after high-bit splitting can be derived and calculated.

[0022] assumed Grounded, the output of the Nth bit can be obtained as: After sorting, we get: ; definition , . Then the above formula is simplified to: ; Pick , .get: ; like and If the resistance values ​​are interchanged, then: ; From the formula, we can see that the above circuit can provide or Adjustment. Control 6*R items, Control 3*R items.

[0023] See also Figure 4 , Figure 4 1 is a circuit diagram of a second type of four-bit digital-to-analog converter with gear adjustment provided in an embodiment of the present application. Figure 4 As shown, the control resistance of each gear is adjusted.

[0024] See also Figure 5 , Figure 5 : is a truth table diagram of a second type of four-bit digital-to-analog converter with gear adjustment provided in an embodiment of the present application. Figure 5 As shown, the truth table of the second type of gear adjustment four-bit D / A converter is given below with N=4. When the definition code value is 1, the , grounded when 0.

[0025] See also Figure 6 , Figure 6 1 is a circuit diagram of a high-precision digital-to-analog converter provided in an embodiment of the present application. Figure 6 As shown, the high-precision digital-to-analog converter 100 provided in the embodiment of the present application includes: a first terminating resistor R J1 , the second terminal resistor R J2 , ladder resistance R T (R T1 , R T2 , R T3 and R T4 )、Control resistor R K (RK1 , R K2 , R K3 and R K4 ) and the voltage stabilizing capacitor C, the first terminal resistor R J1 One end is connected to the ground. The second terminal is connected to the resistor R J2 The first end is connected to the first terminal resistor R J1 The other end is connected to the second terminal resistor R J2 The second end is connected to the reference voltage source V ref Connect the first control resistor R K1 The first end is connected through a ladder resistor R T1 The second terminating resistor R J2 The second end of each control resistor R T The first end of each ladder resistor is connected to another adjacent control resistor R T The first end is connected to the control resistor R T The second end is connected to the ground terminal GND or to the reference voltage source V ref The first end of the voltage stabilizing capacitor C is connected to the last control resistor R K4 The first end of the voltage stabilizing capacitor C is connected to the ground, and the second end of the voltage stabilizing capacitor C is grounded. The first end of the voltage stabilizing capacitor C is the voltage output end of the high-precision digital-to-analog converter 100. ref The preset signal terminal is connected to the preset signal terminal, which is used to transmit a pulse modulation signal (PWM). The voltage signal of the reference voltage source and the pulse modulation signal are combined to form a modulation voltage.

[0026] Make as Figure 6 As shown in the adjustment, add a PWM signal and OUT The voltage stabilizing capacitors are added, and the figure shows the case where the resistor ladder error is within 1 LSB.

[0027] This adjustment raises the output by 1 LSB as a whole, that is, the output of the high-precision digital-to-analog converter 100 increases from [0, ] to [ , ], where N=4.

[0028] right Figure 6 The medium structure can adjust the duty cycle to achieve flexible adjustment between ±0.5LSB. Define the duty cycle of PWM as k, where, , mis is the nonlinear error of DAC. Then the output voltage after adjustment is: ; Ideally, , if the PWM duty cycle k is fine enough, then , then the error of DAC can be infinitely small.

[0029] It should be noted that the duty cycle of PWM is also controlled by the code value and its own performance. For example, the N-bit code value is equivalent to dividing the duty cycle into file, then it is equivalent to dividing the original 1 LSB range into The adjustment accuracy is 1 / LSB, the error can be controlled within 1 / LSB (positive error slightly exceeds 1 / LSB is reduced by one level), at this time the error is (-1 / LSB, 0) range, the negative error is slightly more than 1 / LSB is increased by one level, and the error is (0, 1 / LSB) range).

[0030] See also Figure 7 , Figure 7 Schematic diagram of waveforms of output voltages of various digital-to-analog converters provided in the embodiments of the present application. Figure 7 As shown, the digital control data of multiple digital-to-analog converters are all 0111, that is, the output Taking the example, the waveforms of the original version, the full-gear adjustment version and the version with PWM are given. Figure 8 The DAC referenced in assumes that the original position is 0111. The nonlinear error.

[0031] See also Figure 8 , Figure 8 It is a schematic diagram of partial waveforms of output voltages of two digital-to-analog converters provided in the embodiments of the present application.

[0032] The high-precision digital-to-analog converter 100 provided in the embodiment of the present application only adds a specific level of resistance R compared to a conventional digital-to-analog converter. J2 The composition and control strategy of the voltage stabilizing capacitor C do not require adjustment of the control resistor for each gear. Even as the number of bits of the binary code increases, the area increased by the adjustment in the present application is fixed, and the adjustment of the error is maximized, and the adjustment accuracy is not an integer, which can be adjusted more finely.

[0033] The high-precision digital-to-analog converter 100 provided in the embodiment of the present application has a control strategy that only increases the resistance R of a specific level. J2 Based on the voltage-stabilizing capacitor C, further trimming can be performed by adjusting the duty cycle, which can greatly reduce the area increased for trimming.

[0034] An embodiment of the present application provides a high-precision digital-to-analog converter, which includes: a first termination resistor, a second termination resistor, a ladder resistor, a control resistor and a voltage-stabilizing capacitor, wherein one end of the first termination resistor is connected to the ground terminal; the first end of the second termination resistor is connected to the other end of the first termination resistor, and the second end of the second termination resistor is connected to a reference voltage source; the first end of the first control resistor is connected to the second end of the second termination resistor through a ladder resistor, the first end of each control resistor is connected to the first end of another adjacent control resistor through a ladder resistor, and the second ends of the control resistors are connected to the ground terminal or to the reference voltage source through a switch; the first end of the voltage-stabilizing capacitor is connected to the first end of the last control resistor, the second end of the voltage-stabilizing capacitor is grounded, and the first end of the voltage-stabilizing capacitor is the voltage output end of the high-precision digital-to-analog converter; wherein the reference voltage source is connected to a preset signal end, the preset signal end is used to transmit a pulse modulation signal, and the voltage signal of the reference voltage source and the pulse modulation signal synthesize a modulation voltage. In the above-mentioned high-precision digital-to-analog converter, by adding a pulse modulation signal and a voltage-stabilizing capacitor at the voltage output end, the output signal of the high-precision digital-to-analog converter is adjusted between ±0.5 LSB (Least Significant Bit). If the pulse modulation signal is fine enough, the error of the output voltage of the high-precision converter can be infinitely small. Compared with the traditional full-speed adjustment digital-to-analog converter, not only the accuracy of the output voltage is improved, but also only a second termination resistor and a voltage-stabilizing capacitor are added, thereby reducing the increase in area.

[0035] In order to more clearly introduce the technical solution of the present application, the technical solution of the present application will be introduced through specific embodiments below. It should be noted that the specific embodiments are used to expand the technical solution of the present application, but are not intended to limit the present application.

[0036] In some embodiments, the high-precision digital-to-analog converter further includes: a control unit. The control unit is used to generate digital control data according to an input control instruction, and the digital control data is used to adjust a switch corresponding to the control resistor; the control unit is connected to a preset signal terminal, and is also used to generate a pulse modulation signal according to a preset duty cycle.

[0037] Exemplarily, the high-precision digital-to-analog converter provided in the embodiment of the present application includes a control unit, which is not only used to adjust the switch corresponding to the control resistor, but also used to generate a pulse modulation signal according to a preset duty cycle.

[0038] In some embodiments, the preset signal terminal is connected to an external signal generating unit, and the signal generating unit is used to generate a pulse modulation signal according to a preset duty cycle.

[0039] Exemplarily, the pulse modulation signal may also be generated by an external signal generating unit.

[0040] In some embodiments, the duty cycle ranges from 0 to 1.

[0041] It should be noted that the duty cycle of PWM is also controlled by the code value and its own performance. For example, the N-bit code value is equivalent to dividing the duty cycle into file, then it is equivalent to dividing the original 1 LSB range into The adjustment accuracy is 1 / LSB, the error can be controlled within 1 / LSB (positive error slightly exceeds 1 / LSB is reduced by one level), at this time the error is (-1 / LSB, 0) range, the negative error is slightly more than 1 / LSB is increased by one level, and the error is (0, 1 / LSB) range).

[0042] An embodiment of the present application also provides an electronic device, comprising a high-precision digital-to-analog converter as described in any one of the embodiments of the present application.

[0043] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A high-precision digital-to-analog converter, characterized in that: The high-precision digital-to-analog converter comprises: A first terminating resistor, one end of which is connected to the ground terminal; a second termination resistor, wherein a first end of the second termination resistor is connected to the other end of the first termination resistor, and a second end of the second termination resistor is connected to a reference voltage source; Ladder resistance; Control resistors, wherein the first end of the first control resistor is connected to the second end of the second terminal resistor through one of the ladder resistors, the first end of each of the control resistors is connected to the first end of another adjacent control resistor through one of the ladder resistors, and the second ends of the control resistors are connected to the ground terminal or the reference voltage source through a switch; A voltage stabilizing capacitor, wherein a first end of the voltage stabilizing capacitor is connected to a first end of the last control resistor, a second end of the voltage stabilizing capacitor is grounded, and the first end of the voltage stabilizing capacitor is a voltage output end of the high-precision digital-to-analog converter; The reference voltage source is connected to a preset signal terminal, the preset signal terminal is used to transmit a pulse modulation signal, and the voltage signal of the reference voltage source and the pulse modulation signal are combined to form a modulation voltage.

2. The high-precision digital-to-analog converter according to claim 1, characterized in that: The high-precision digital-to-analog converter also includes: A control unit, the control unit is used to generate digital control data according to an input control instruction, and the digital control data is used to adjust the switch corresponding to the control resistor; the control unit is connected to the preset signal terminal and is also used to generate the pulse modulation signal according to a preset duty cycle.

3. The high-precision digital-to-analog converter according to claim 1, characterized in that: The preset signal end is connected to an external signal generating unit, and the signal generating unit is used to generate the pulse modulation signal according to a preset duty cycle.

4. The high-precision digital-to-analog converter according to any one of claims 2 or 3, characterized in that: The duty cycle ranges from 0 to 1.

5. An electronic device, characterized in that: The invention comprises a high-precision digital-to-analog converter as claimed in any one of claims 1 to 4.

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