CN109309498B - A Current Steering Digital-to-Analog Converter Based on Thermometer Code - Google Patents

The invention relates to the technical field of integrated circuits, and discloses a current steering type digital-to-analog converter based on thermometer codes. The digital-to-analog converter converts the traditional current source array with the current value in binary multiple relation into the current source with the current value being a single value, so that the current mismatch is relatively small, and the conversion precision of the digital-to-analog converter is effectively improved.

一种基于温度计码的电流舵型数模转换器A Current Steering Digital-to-Analog Converter Based on Thermometer Code

技术领域technical field

本发明属于集成电路技术领域，特别涉及一种基于温度计码的电流舵型数模转换器。The invention belongs to the technical field of integrated circuits, and in particular relates to a current steering digital-to-analog converter based on a thermometer code.

背景技术Background technique

数模转换器(Digital to Analog Converter，简称DAC)是能够将数字信号转换为模拟信号的一种信号转换器，广泛应用于需要进行信号处理的各个领域。数模转换器有多种类型，其中电流舵型数模转换器(Current Steering Digital to Analog Converter)是一种常用的数模转换器结构，具有匹配精度高、响应速度快的优势，在高速且对匹配性要求较高的电路中有着广泛的应用，并且电流舵型数模转换器的能量利用率较高，当对输出信号进行差分利用时几乎能将所有的能量输出。A digital-to-analog converter (DAC) is a signal converter capable of converting a digital signal into an analog signal, and is widely used in various fields that require signal processing. There are many types of digital-to-analog converters. Among them, the current steering digital-to-analog converter (Current Steering Digital to Analog Converter) is a commonly used digital-to-analog converter structure, which has the advantages of high matching accuracy and fast response speed. It is widely used in circuits with high matching requirements, and the energy utilization rate of the current steered digital-to-analog converter is relatively high. When the output signal is differentially utilized, almost all the energy can be output.

然而，常规的电流舵型数模转换器使用电流值成二进制倍数关系的电流源阵列，由于电流源受限于电阻值的匹配精度，由于工艺、光刻等原因导致电阻值并不完全相同的时候，进而不可避免的存在着失配，直接影响到数模转换的精度。数模转换器所能达到的精度，一定程度上取决于电流源的失配误差。因此，如何降低电流源阵列的电流失配，进而提高数模转换器的转换精度是急需解决的技术问题。However, the conventional current steering type digital-to-analog converter uses a current source array whose current value is a binary multiple. Since the current source is limited by the matching accuracy of the resistance value, the resistance values are not exactly the same due to reasons such as process and lithography. time, and then inevitably there is a mismatch, which directly affects the accuracy of the digital-to-analog conversion. The accuracy that a digital-to-analog converter can achieve depends in part on the mismatch error of the current source. Therefore, how to reduce the current mismatch of the current source array and further improve the conversion accuracy of the digital-to-analog converter is a technical problem that needs to be solved urgently.

发明内容SUMMARY OF THE INVENTION

针对现有技术存在的问题，本发明提出一种基于温度计码的电流舵型数模转换器，通过引入译码电路将二进制数字输入信号转换为温度计码数字控制信号输出，将传统的电流值成二进制倍数关系的电流源阵列转换为电流值为单一值的电流源，并用温度计码数字信号进行控制，由于新的电流源阵列中电流值为单一值，使得电流源阵列的电流失配相对比较小，进而有效提高的数模转换器的转换精度。In view of the problems existing in the prior art, the present invention proposes a current rudder type digital-to-analog converter based on thermometer code. By introducing a decoding circuit, the binary digital input signal is converted into a thermometer code digital control signal output, and the traditional current value is converted into a digital control signal output. The current source array with binary multiple relationship is converted into a current source with a single value of current, and is controlled by a digital signal of thermometer code. Since the current value in the new current source array is a single value, the current mismatch of the current source array is relatively small. , thereby effectively improving the conversion accuracy of the digital-to-analog converter.

为了实现上述技术目的，本发明实施例采用如下技术方案：In order to achieve the above technical purpose, the embodiment of the present invention adopts the following technical solutions:

一种基于温度计码的电流舵型数模转换器，该数模转换器包括译码电路、电流源模块、比较器模块、负载电阻模块与反馈电阻模块，译码电路的一端接入数字输入信号，译码电路的另一端与电流源模块的一端相连，电流源模块的另一端与比较器模块的反向输入端相连，比较器模块的输出端与反馈电阻模块的一端相连，反馈电阻模块的另一端分别与比较器模块的反向输入端和负载电阻模块的一端相连，译码电路将二进制码的数字输入信号转换为温度计码的数字控制信号。A current rudder type digital-to-analog converter based on thermometer code, the digital-to-analog converter includes a decoding circuit, a current source module, a comparator module, a load resistance module and a feedback resistance module, and one end of the decoding circuit is connected to a digital input signal , the other end of the decoding circuit is connected to one end of the current source module, the other end of the current source module is connected to the reverse input end of the comparator module, the output end of the comparator module is connected to one end of the feedback resistance module, and the The other end is respectively connected with the reverse input end of the comparator module and one end of the load resistance module, and the decoding circuit converts the digital input signal of binary code into digital control signal of thermometer code.

进一步的，二进制码的数字输入信号为n位，n为大于等于1的自然数。Further, the digital input signal of the binary code is n bits, and n is a natural number greater than or equal to 1.

进一步的，译码电路将n位二进制码的数字输入信号D_n转换为2ⁿ-1位温度计码的数字控制信号。Further, the decoding circuit converts the digital input signal Dn of _n -bit binary code into a digital control signal of ²ⁿ -1-bit thermometer code.

进一步的，电流源模块包括电流源阵列，电流源阵列包括i个电流值相同的电流源I_i，每个电流源I_i的一端接入相应数字控制信号，每个电流源I_i的另一端与相应开关K_i的一端相接，i为1到2ⁿ-1的自然数。Further, the current source module includes a current source array, the current source array includes i current sources I _i with the same current value, one end of each current source I _i is connected to a corresponding digital control signal, and the other end of each current source I _i is connected. Connected to one end of the corresponding switch K _i , where i is a natural number from 1 to 2 ⁿ -1.

进一步的，开关K_i的另一端依次相连并接入比较器模块的反向输入端。Further, the other ends of the switches K _i are connected in sequence and connected to the inverting input end of the comparator module.

进一步的，比较器模块包括基于运算放大器的比较器，比较器的正向输入端接入参考电压V_ref。Further, the comparator module includes a comparator based on an operational amplifier, and the non-inverting input terminal of the comparator is connected to the reference voltage V _ref .

进一步的，负载电阻模块包括负载电阻R₀，负载电阻R₀的另一端接地。Further, the load resistance module includes a load resistance R ₀ , and the other end of the load resistance R ₀ is grounded.

进一步的，反馈电阻模块包括反馈电阻R₁，反馈电阻R₁的一端与比较器的输入端相连，反馈电阻R₁的另一端与比较器的反向输入端相连。Further, the feedback resistor module includes a feedback resistor R ₁ , one end of the feedback resistor R ₁ is connected to the input end of the comparator, and the other end of the feedback resistor R ₁ is connected to the inverting input end of the comparator.

进一步的，数模转换器的输出电压V_out为：Further, the output voltage V _out of the digital-to-analog converter is:

相较于现有技术，本发明具有如下技术效果：Compared with the prior art, the present invention has the following technical effects:

本发明提出了一种基于温度计码的电流舵型数模转换器，该数模转换器包括译码电路、电流源模块、比较器模块、负载电阻模块与反馈电阻模块，译码电路的一端接入数字输入信号，译码电路的另一端与电流源模块的一端相连，电流源模块的另一端与比较器模块的反向输入端相连，比较器模块的输出端与反馈电阻模块的一端相连，反馈电阻模块的另一端分别与比较器模块的反向输入端和负载电阻模块的一端相连，译码电路将二进制码的数字输入信号转换为温度计码的数字控制信号。上述数模转换器通过引入译码电路将二进制数字输入信号转换为温度计码数字控制信号输出，将传统的电流值成二进制倍数关系的电流源阵列转换为电流值为单一值的电流源，并用温度计码数字信号进行控制，由于新的电流源阵列中电流值为单一值，使得电流源阵列的电流失配相对比较小，进而有效提高的数模转换器的转换精度。The invention provides a current rudder type digital-to-analog converter based on thermometer code. The digital-to-analog converter includes a decoding circuit, a current source module, a comparator module, a load resistance module and a feedback resistance module. One end of the decoding circuit is connected to The other end of the decoding circuit is connected to one end of the current source module, the other end of the current source module is connected to the reverse input end of the comparator module, the output end of the comparator module is connected to one end of the feedback resistance module, The other end of the feedback resistance module is respectively connected with the reverse input end of the comparator module and one end of the load resistance module, and the decoding circuit converts the digital input signal of binary code into digital control signal of thermometer code. The above-mentioned digital-to-analog converter converts the binary digital input signal into a thermometer code digital control signal output by introducing a decoding circuit, and converts the traditional current source array whose current value is a binary multiple into a current source whose current value is a single value. Since the current value in the new current source array is a single value, the current mismatch of the current source array is relatively small, thereby effectively improving the conversion accuracy of the digital-to-analog converter.

附图说明Description of drawings

图1为本发明实施例提出的一种基于温度计码的电流舵型数模转换器的电路结构图；1 is a circuit structure diagram of a thermometer code-based current steering digital-to-analog converter proposed in an embodiment of the present invention;

图2为本发明实施例提出的一种基于温度计码的电流舵型数模转换器的电路原理图。FIG. 2 is a circuit schematic diagram of a current steered digital-to-analog converter based on a thermometer code according to an embodiment of the present invention.

其中：1、译码电路；2、电流源模块；3、比较器模块；4、负载电阻模块；5、反馈电阻模块。Among them: 1. Decoding circuit; 2. Current source module; 3. Comparator module; 4. Load resistance module; 5. Feedback resistance module.

具体实施方式Detailed ways

下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

另外，本文中术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。In addition, the term "and/or" in this article is only an association relationship to describe the associated objects, indicating that there can be three kinds of relationships, for example, A and/or B, it can mean that A exists alone, A and B exist at the same time, There are three cases of B alone. In addition, the character "/" in this document generally indicates that the related objects are an "or" relationship.

如图1所示，本发明实施例提出了一种基于温度计码的电流舵型数模转换器，该数模转换器包括译码电路1、电流源模块2、比较器模块3、负载电阻模块4与反馈电阻模块5，译码电路1的一端接入数字输入信号，译码电路1的另一端与电流源模块2的一端相连，电流源模块2的另一端与比较器模块3的反向输入端相连，比较器模块3的输出端与反馈电阻模块5的一端相连，反馈电阻模块5的另一端分别与比较器模块3的反向输入端和负载电阻模块4的一端相连，译码电路1将二进制码的数字输入信号转换为温度计码的数字控制信号。As shown in FIG. 1 , an embodiment of the present invention proposes a current steering digital-to-analog converter based on a thermometer code. The digital-to-analog converter includes a decoding circuit 1 , a current source module 2 , a comparator module 3 , and a load resistance module 4 and the feedback resistor module 5, one end of the decoding circuit 1 is connected to the digital input signal, the other end of the decoding circuit 1 is connected to one end of the current source module 2, and the other end of the current source module 2 is connected to the inverse of the comparator module 3 The input end is connected, the output end of the comparator module 3 is connected with one end of the feedback resistance module 5, the other end of the feedback resistance module 5 is respectively connected with the reverse input end of the comparator module 3 and one end of the load resistance module 4, the decoding circuit 1 Convert the digital input signal of binary code to the digital control signal of thermometer code.

其中，数模转换器的二进制码的数字输入信号为n位，n为大于等于1的自然数，数字输入信号相应的译码电路1的输入端。The digital input signal of the binary code of the digital-to-analog converter is n bits, n is a natural number greater than or equal to 1, and the digital input signal corresponds to the input end of the decoding circuit 1 .

如图2所示，译码电路1将n位二进制码的数字输入信号D_n转换为2ⁿ-1位温度计码的数字控制信号，从而将传统的电流值成二进制倍数关系的电流源阵列转换为电流值为单一值的电流源，并用温度计码数字信号进行控制，由于新的电流源阵列中电流值为单一值，传统的电流值成二进制倍数关系的电流值，电流源阵列的电流失配相对比较小。As shown in Figure 2, the decoding circuit 1 converts the digital input signal Dn of _n -bit binary code into a digital control signal of ²ⁿ -1-bit thermometer code, thereby converting the traditional current value into a current source array with a binary multiple relationship It is a current source whose current value is a single value, and is controlled by a digital signal of thermometer code. Since the current value in the new current source array is a single value, the traditional current value is a binary multiple of the current value, and the current of the current source array is mismatched. relatively small.

示例的，译码电路1将二进制码的数字输入信号D₀、D₁、D₂、D₃、。。。D_n-1，相应的转换为2ⁿ-1位温度计码的数字控制信号。Exemplarily, the decoding circuit 1 inputs the digital input signals D ₀ , D ₁ , D ₂ , D ₃ , of binary codes. . . D _n-1 , correspondingly converted into a digital control signal of a 2 ⁿ -1 bit thermometer code.

电流源模块2包括电流源阵列，电流源阵列包括i个电流值相同的电流源I_i，每个电流源I_i的一端分别接入相应数字控制信号，每个电流源I_i的另一端与相应开关K_i的一端相接，i为1到2ⁿ-1的自然数。每个开关Ki由温度计码数字控制信号进行控制，且每个电流源I_i分别接入电源值相同的数字控制信号。The current source module 2 includes a current source array, the current source array includes i current sources I _i with the same current value, one end of each current source I _i is respectively connected to a corresponding digital control signal, and the other end of each current source I _i is connected to One ends of the corresponding switches K _i are connected, and i is a natural number from 1 to 2 ⁿ -1. Each switch Ki is controlled by a thermometer code digital control signal, and each current source I _i is respectively connected to a digital control signal with the same power value.

优选的，每个开关K_i的另一端依次相连并接入比较器模块3的反向输入端。Preferably, the other end of each switch K _i is connected in sequence and connected to the inverting input end of the comparator module 3 .

示例的，开关相应的包括K₁、K₂、。。。、K₂ ⁿ _-2、K₂ ⁿ _-1 By way of example, the switches correspondingly include K ₁ , K ₂ , . . . , K ₂ ⁿ _-2 , K ₂ ⁿ _-1

比较器模块3包括基于运算放大器的比较器，包括正相输入端、反相输入端与输出端，其中正向输入端接入参考电压V_ref，反相输入端分别与电流源模块2、反馈电阻模块5的一端、负载电阻模块4的一端相连，输出端输出相应电压。The comparator module 3 includes a comparator based on an operational amplifier, including a non-inverting input terminal, an inverting input terminal and an output terminal, wherein the non-inverting input terminal is connected to the reference voltage V _ref , and the inverting input terminal is respectively connected with the current source module 2 and the feedback terminal. One end of the resistance module 5 and one end of the load resistance module 4 are connected, and the output end outputs a corresponding voltage.

负载电阻模块4包括负载电阻R₀，负载电阻R₀的一端与比较器模块的反向输入端相接，负载电阻R₀的另一端接地。具体的，负载电阻R₀的电阻值为R，R的具体数值需要根据实际情况而具体设定，在此仅作为一个标识。The load resistor module 4 includes a load resistor R ₀ , one end of the load resistor R ₀ is connected to the reverse input end of the comparator module, and the other end of the load resistor R ₀ is grounded. Specifically, the resistance value of the load resistor R ₀ is R, and the specific value of R needs to be specifically set according to the actual situation, which is only used as an indicator here.

反馈电阻模块5包括反馈电阻R₁，反馈电阻R₁的一端与比较器模块3的反相输入端相连，另一端与比较器模块3的输出端相连。具体的，反馈电阻R₁的电阻值为R，R的具体数值需要根据实际情况而具体设定，在此仅作为一个标识。The feedback resistor module 5 includes a feedback resistor R ₁ , one end of the feedback resistor R ₁ is connected to the inverting input end of the comparator module 3 , and the other end is connected to the output end of the comparator module 3 . Specifically, the resistance value of the feedback resistor R ₁ is R, and the specific value of R needs to be specifically set according to the actual situation, which is only used as an indicator here.

上述基于温度计码的电流舵型数模转换器，引入译码电路将二进制数字输入信号转换为温度计码数字控制信号输出，将传统的电流值成二进制倍数关系的电流源阵列转换为电流值为单一值的电流源，并用温度计码数字信号进行控制，由于新的电流源阵列中电流值为单一值，使得电流源阵列的电流失配相对比较小，进而有效提高的数模转换器的转换精度。The above-mentioned thermometer code-based current rudder digital-to-analog converter introduces a decoding circuit to convert the binary digital input signal into a thermometer code digital control signal output, and converts the traditional current source array whose current value is a binary multiple into a single current value. Since the current value in the new current source array is a single value, the current mismatch of the current source array is relatively small, thereby effectively improving the conversion accuracy of the digital-to-analog converter.

优选的，如图2所示，数模转换器的输出电压V_out为：Preferably, as shown in FIG. 2 , the output voltage V _out of the digital-to-analog converter is:

其中，合理的选取V_ref、I、R₀、R₁的值，就可以让数模转换器的模拟输出电压处于所需要的范围。Among them, reasonable selection of the values of V _ref , I, R ₀ , and R ₁ can make the analog output voltage of the digital-to-analog converter be in the required range.

综上，本发明提出了一种基于温度计码的电流舵型数模转换器，该数模转换器包括译码电路、电流源模块、比较器模块、负载电阻模块与反馈电阻模块，译码电路的一端接入数字输入信号，译码电路的另一端与电流源模块的一端相连，电流源模块的另一端与比较器模块的反向输入端相连，比较器模块的输出端与反馈电阻模块的一端相连，反馈电阻模块的另一端分别与比较器模块的反向输入端和负载电阻模块的一端相连，译码电路将二进制码的数字输入信号转换为温度计码的数字控制信号。上述数模转换器通过引入译码电路将二进制数字输入信号转换为温度计码数字控制信号输出，将传统的电流值成二进制倍数关系的电流源阵列转换为电流值为单一值的电流源，并用温度计码数字信号进行控制，由于新的电流源阵列中电流值为单一值，使得电流源阵列的电流失配相对比较小，进而有效提高的数模转换器的转换精度。To sum up, the present invention proposes a current steered digital-to-analog converter based on thermometer code. The digital-to-analog converter includes a decoding circuit, a current source module, a comparator module, a load resistance module, a feedback resistance module, and a decoding circuit. One end is connected to the digital input signal, the other end of the decoding circuit is connected to one end of the current source module, the other end of the current source module is connected to the reverse input end of the comparator module, and the output end of the comparator module is connected to the feedback resistance module. One end is connected, and the other end of the feedback resistance module is connected to the inverting input end of the comparator module and one end of the load resistance module respectively, and the decoding circuit converts the digital input signal of binary code into digital control signal of thermometer code. The above-mentioned digital-to-analog converter converts the binary digital input signal into a thermometer code digital control signal output by introducing a decoding circuit, and converts the traditional current source array whose current value is a binary multiple into a current source whose current value is a single value. Since the current value in the new current source array is a single value, the current mismatch of the current source array is relatively small, thereby effectively improving the conversion accuracy of the digital-to-analog converter.

通过以上的实施方式的描述，所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，仅以上述各功能单元的划分进行举例说明，实际应用中，可以根据需要而将上述功能分配由不同的功能单元完成，即将装置的内部结构划分成不同的功能单元，以完成以上描述的全部或者部分功能。上述描述的系统，装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。From the description of the above embodiments, those skilled in the art can clearly understand that for the convenience and brevity of the description, only the division of the above functional units is used as an example for illustration. In practical applications, the above functions can be allocated as required. It is completed by different functional units, that is, the internal structure of the device is divided into different functional units, so as to complete all or part of the functions described above. For the specific working process of the system, apparatus and unit described above, reference may be made to the corresponding process in the foregoing method embodiments, and details are not described herein again.

以上所述，仅为本发明的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以所述权利要求的保护范围为准。The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention. should be included within the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.