CN110855294B

CN110855294B - Circuit module and digital-to-analog converter

Info

Publication number: CN110855294B
Application number: CN201810947833.7A
Authority: CN
Inventors: 刘菁
Original assignee: SG Micro Beijing Co Ltd
Current assignee: SG Micro Beijing Co Ltd
Priority date: 2018-08-20
Filing date: 2018-08-20
Publication date: 2023-08-25
Anticipated expiration: 2038-08-20
Also published as: CN110855294A

Abstract

The application discloses a circuit module, comprising: the switching network comprises a plurality of stages of switching tubes, each stage of switching tube provides voltage to be transmitted in a conduction stage, and the voltage generation module is used for providing a plurality of first voltages according to reference voltages, wherein substrates of the plurality of switching tubes are separated from each other, and the first voltages are used for providing substrate voltages for the switching tubes. The normal conduction of all the switches is ensured, the threshold voltage of the switches is not too large, and the on-resistance of the switches is increased; meanwhile, the area and parasitic capacitance of the switch are not increased, and large spike voltage is not generated in the switching process of the switch. The application also discloses a digital-to-analog converter.

Description

Circuit module and digital-to-analog converter

Technical Field

The present application relates to the field of integrated circuit fabrication, and more particularly to a circuit module and a digital-to-analog converter.

Background

A Metal-Oxide-semiconductor field effect transistor (MOSFET) is the basis of an integrated circuit. The MOSFET is fabricated on a substrate, and two heavily doped regions, source and Drain, are formed on the substrate. Then, silicon dioxide is used as an insulating layer on the substrate, which is a gate oxide layer or a gate insulating layer, and a gate (Grid) is arranged on the gate oxide layer.

The potential of the substrate in the circuit has a great influence on the performance of the device, and if the potential of the substrate is not equal to the source potential, a body effect is caused inside the device, resulting in the shift of the threshold voltage. Fig. 1a to 1c show several connection methods of substrate potentials according to the prior art. As shown in fig. 1a, the substrate of the MOS transistor is connected to a fixed potential, for example, the substrate of the PMOS transistor is connected to a high potential Vdd, and the substrate of the NMOS transistor is connected to a low potential GND. In this structure, since the voltage drop between the source and the substrate is large, the threshold voltage of the MOS transistor is correspondingly large, so in the low supply voltage circuit, when the switching transistor needs to transmit an intermediate potential (such as VDD/2), the on-resistance is very large, so that a large switching area is required, and even the MOS transistor may not be turned on under some voltage, so that the voltage cannot be transmitted.

Fig. 1b shows another connection method according to the prior art, as shown in fig. 1b, connecting the substrate and the source of the MOS transistor together so that their potentials are equal. However, this structure must ensure that the source potential is fixed higher (PMOS transistor) or lower (NMOS transistor) than the drain potential, i.e., the source-drain potential difference can only be fixed to be either positive or negative. However, when most of the MOS transistors work in the on-off state, the electric potential at two ends of the MOS transistor cannot ensure that one end is always higher than the other end. And the substrate and the source electrode of the MOS tube are connected together to cause the source electrode potential of the MOS tube to change in the switching process of the switch, so that when the MOS tube works at different voltages, the spike voltage difference generated by switching of the switch is larger.

Fig. 1c shows another connection method according to the prior art, as shown in fig. 1c, for a MOS transistor structure connected in series, the substrate can be connected to an intermediate floating potential. This structure requires two MOS transistors of exactly the same size, thus increasing the area of the circuit; in addition, as the intermediate potential is floating, the intermediate potential can change along with the voltage at the two ends of the MOS tube during switching of the switch, and the change is uncontrollable, so that a plurality of random spike voltages are easy to occur during switching of the switch.

Therefore, an improvement is needed in the prior art to obtain a circuit module, which can reduce the on-resistance of the MOS transistor without generating random spike voltage.

Disclosure of Invention

In view of the above, the present application is directed to a circuit module and a digital-to-analog converter, which can reduce the on-resistance of the MOS transistor without generating random spike voltage.

According to an aspect of the present application, there is provided a circuit module including: the switching network comprises a plurality of stages of switching tubes, each stage of switching tube provides voltage to be transmitted in a conduction stage, and the voltage generation module is used for providing a plurality of first voltages according to reference voltages, wherein substrates of the plurality of switching tubes are separated from each other, and the first voltages are used for providing substrate voltages for the switching tubes.

Preferably, the voltage value of the voltage to be transmitted increases with the number of stages of the switching tube.

Preferably, the number of the plurality of first voltages is equal to the number of the switching tubes, and each of the first voltages supplies the substrate voltage to the switching tube corresponding thereto.

Preferably, the number of the plurality of first voltages is smaller than the number of the switching tubes, and each of the first voltages supplies the substrate voltage to the plurality of switching tubes.

Preferably, the voltage generation module includes a first resistor string connected in series between the reference voltage and ground, the first resistor string being configured to derive the plurality of first voltages from the reference voltage.

Preferably, the first resistor string comprises a plurality of first resistors and second resistors connected in series, wherein the first resistors are connected to the head end and the tail end of the first resistor string, and the second resistors are located in the middle of the first resistor string.

Preferably, the resistance of the first resistor is one half of the resistance of the second resistor.

Preferably, the multi-stage switching tube is selected from NMOS tube and/or PMOS tube.

According to another aspect of the present application there is provided a digital to analogue converter comprising: a second resistor string including a plurality of third resistors connected between a reference voltage and a reference ground, and the circuit module described above, wherein the circuit module includes: the switching network is used for selecting at least one third resistor in the second resistor string according to an input digital signal, and comprises a plurality of switching tubes which output analog signals corresponding to the digital signal in a conduction stage; and the voltage generation module is used for providing a plurality of first voltages according to the reference voltage, wherein the substrates of the switch tubes are mutually separated, and the first voltages are used for providing substrate voltages for the switch tubes.

According to a third aspect of the present application there is provided a digital to analogue converter comprising: the current source network comprises a plurality of current sources and the circuit module, wherein the circuit module comprises: the switching network is used for selecting at least one current source in the current source network according to an input digital signal, and comprises a plurality of switching tubes which output analog signals corresponding to the digital signal in a conduction stage; and the voltage generation module is used for providing a plurality of first voltages according to the reference voltage, wherein the substrates of the switch tubes are mutually separated, and the first voltages are used for providing substrate voltages for the switch tubes.

The circuit module and the digital-to-analog converter comprise a voltage generation module which is used for generating substrate voltages of a plurality of switches in a switch network, so that normal conduction of all the switches is ensured, the threshold voltage of the switches is not too large, and the on-resistance of the switches is increased; meanwhile, the area and parasitic capacitance of the switch are not increased, and large spike voltage is not generated in the switching process of the switch.

In a preferred embodiment, the voltage generation module obtains a substrate voltage of a fixed potential, so that the voltage value of the substrate voltage of the switching tube does not change with the switching of the switch, and the voltage on the resistor string in the digital-to-analog converter is not affected. Therefore, the digital-to-analog converter comprising the voltage generation module has good consistency of spike voltage generated during switching of the switch under different conditions, and does not change along with the change of the transmission voltage value.

In a preferred embodiment, by adjusting the relation between the resistor in the voltage generating module and the resistor of the resistor string of the digital-to-analog converter, when the external environment (such as the power supply voltage, the reference voltage, the temperature, the process angle, etc.) changes, the substrate voltage of the switching tube and the voltage to be transmitted can be ensured to have corresponding proportion changes, and the reliability of the circuit is further improved.

In the preferred embodiment, for the digital-to-analog converter with higher digits, the voltage value difference between the resistors in the resistor string of the digital-to-analog converter is smaller, so that a plurality of switching tubes in a switching network can be grouped, and different switching tubes in the same group use the same first voltage value and second voltage value, so that normal conduction of all the switches is ensured, the threshold voltage of the switches is not too large, and the on-resistance of the switches is increased; without increasing the logic complexity of the voltage generation module and the digital-to-analog converter.

Drawings

The above and other objects, features and advantages of the present application will become more apparent from the following description of embodiments of the present application with reference to the accompanying drawings.

Fig. 1a shows a schematic structure of a substrate potential connection method according to the prior art.

Fig. 1b shows a schematic structure of another substrate potential connection method according to the prior art.

Fig. 1c shows a schematic structure of another substrate potential connection method according to the prior art.

Fig. 2 shows a schematic diagram of a resistive digital-to-analog converter according to a first embodiment of the application.

Fig. 3 shows another structural diagram of a resistive digital-to-analog converter according to a first embodiment of the present application.

Fig. 4 shows a schematic diagram of a structure of a current mode digital-to-analog converter according to a second embodiment of the present application.

Fig. 5 shows another schematic structure of a current mode digital-to-analog converter according to a second embodiment of the present application.

Fig. 6 shows a schematic diagram of a resistive digital-to-analog converter according to a third embodiment of the present application.

Fig. 7 is a schematic diagram showing another structure of a resistive digital-to-analog converter according to a third embodiment of the present application.

Detailed Description

The application will be described in more detail below with reference to the accompanying drawings. Like elements are denoted by like reference numerals throughout the various figures. For clarity, the various features of the drawings are not drawn to scale. Furthermore, some well-known portions may not be shown in the drawings.

Numerous specific details of the application, such as construction, materials, dimensions, processing techniques and technologies, may be set forth in the following description in order to provide a thorough understanding of the application. However, as will be understood by those skilled in the art, the present application may be practiced without these specific details.

It should be understood that in the following description, "circuit" refers to an electrically conductive loop formed by at least one element or sub-circuit through electrical or electromagnetic connection. When an element or circuit is referred to as being "connected to" another element or being "connected between" two nodes, it can be directly coupled or connected to the other element or intervening elements may be present, the connection between the elements may be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled to" or "directly connected to" another element, it means that there are no intervening elements present between the two.

Fig. 2 and 3 show a digital-to-analog converter 100 for converting an N-bit digital signal into an analog signal according to a first embodiment of the present application, the digital-to-analog converter 100 may be implemented as a stand-alone module or in combination with other modules by an integrated circuit. The digital-to-analog converter 100 includes a resistor string 110, a switching network 120, and a voltage generation module 130.

Resistor string 110 includes resistors Ra4-Ra1 connected in series between a reference voltage Vref and ground. Wherein, the resistance values of the resistors Ra1-Ra4 are equal. It is noted that the resistors Ra1, ra2, ra3 and Ra4 have connection terminals at both ends thereof, for example: the resistor Ra1 has a terminal T1 and a terminal T2 at both ends, the resistor Ra2 has a terminal T2 and a terminal T3, the resistor Ra3 has a terminal T3 and a terminal T4, and the resistor Ra4 has a terminal T4 and a terminal T5, as shown in fig. 2 and 3. Resistors Ra1-Ra4 in resistor string 110 generate voltages at terminals T1-T5 in response to the current fed by reference voltage Vref.

The switching network 120 includes (2 ^N/2 +1) switching tubes, N being an even number greater than 0, the plurality of switching tubes being correspondingly connected to a plurality of connection terminals in the resistor string 110. For example, in the present embodiment, the switching network 120 includes switching transistors SM0 to SM4, and as shown in fig. 2 and 3, first path ends of the switching transistors SM0, SM1, SM2, SM3, and SM4 are connected to terminals T1, T2, T3, T4, and T5, respectively, and second path ends are connected to analog signal output ends.

The on and off states of the switching tubes SM0, SM1, SM2, SM3 and SM4 are controlled by control signals generated by the decoding circuit, respectively.

The switching transistors SM0, SM1, SM2, SM3 and SM4 in the present embodiment may be implemented by Metal-Oxide-semiconductor field effect transistors (MOSFETs), which are not limited in this respect, and may be selected by those skilled in the art according to specific situations.

In the following embodiments, the switching transistors SM0, SM1, SM2, SM3, and SM4 will be described as MOS transistors. As shown in fig. 2, the switching transistors SM0, SM1, SM2, SM3 and SM4 are NMOS transistors, or as shown in fig. 3, the switching transistors SM0, SM1, SM2, SM3 and SM4 are PMOS transistors.

The digital-to-analog converter 100 further comprises a voltage generation module 130, wherein the voltage generation module 130 is configured to obtain a plurality of first voltages according to the reference voltage Vref, and the first voltages are configured to provide substrate voltages to the switching transistors SM0, SM1, SM2, SM3 and SM 4. The voltage generation module 130 includes a plurality of resistors Rc1-Rc9 connected in series between the reference voltage Vref and ground, wherein the resistors Rc2-Rc8 have equal resistance values, and the resistors Rc1 and Rc9 have equal resistance values and are half of the resistors Rc2-Rc 8. The resistors Rc1 to Rc9 have connection terminals at both ends, for example: the resistor Rc1 has a terminal Q1 and a terminal Q2 at both ends, the resistor Rc2 has a terminal Q2 and a terminal Q3, the resistor Rc3 has a terminal Q3 and a terminal Q4, the resistor Rc4 has a terminal Q4 and a terminal Q5, and so on, as shown in fig. 2 and 3. The connection terminals at both ends of the resistors Rc1 to Rc9 are used for corresponding connection with the substrates of the switching transistors SM0, SM1, SM2, SM3, and SM4 in the switching network 120. The resistors Rc1-Rc9 are used to generate a substrate voltage corresponding to the switching tube at both ends thereof in response to the current fed by the reference voltage Vref.

In the present embodiment, the resistor string 110 generates voltages v1= V, VT2 =vref/4, v3=vref/2, v4=3vref/4, v5=vref at terminals T1-T5, respectively, in response to the current fed by the reference voltage Vref.

The voltage generation module 130 generates voltages vq1= V, VQ2 =vref/16, vq3=3vref/16, vq4=5vref/16, vq5=7vref/16, vq6=9vref/16, vq7=11vref/16, vq8=13vref/16, vq9=15vref/16, vq10=vref at terminals Q1-Q10, respectively, in response to the current fed by the reference voltage Vref. The voltage values obtained by the voltage generation module 130 can thus cover all voltage values in the resistor string 110 in the digital-to-analog converter 100, which voltages can be used as the substrate voltages for the switching transistors SM0, SM1, SM2, SM3 and SM4 in the switching network 120. Specifically, as shown in fig. 2, for the switching network of the NMOS transistor structure, substrates of the switching transistors SM0, SM1, SM2, SM3, and SM4 are connected to the terminals Q1, Q3, Q5, Q7, and Q9, respectively; in another configuration, as shown in fig. 3, for the switching network of the PMOS transistor structure, substrates of the switching transistors SM0, SM1, SM2, SM3, and SM4 are connected to the terminals Q2, Q4, Q6, Q8, and Q10, respectively. The terminals Q1, Q3, Q5, Q7 and Q9 respectively provide first voltage values for the substrate voltages of the switching transistors SM0, SM1, SM2, SM3 and SM4 of the NMOS structure to the switching transistors SM0, SM1, SM2, SM3 and SM4 of the NMOS structure; terminals Q2, Q4, Q6, Q8 and Q10 provide second voltage values to the PMOS structured switching transistors SM0, SM1, SM2, SM3 and SM4, respectively, which are used for the substrate voltages of the PMOS structured switching transistors SM0, SM1, SM2, SM3 and SM4, respectively.

In addition, the first voltage value and the second voltage value obtained by the grounding end and the terminal connected with the reference voltage Vref end are equal to the voltage value required to be transmitted by the corresponding switching tube; the first voltage values obtained by other terminals in the voltage generating module 130 are lower than the voltage values required to be transmitted by the corresponding switching tubes by Vref/16, and the second voltage values are higher than the voltage values required to be transmitted by the corresponding switching tubes by Vref/16. Thus, not only is the normal conduction of all the switches ensured, but also the threshold voltage of the switch is not too large, and the on-resistance of the switch is increased; meanwhile, the area and parasitic capacitance of the switch are not increased, so that large spike voltage cannot occur in the switching process of the switch.

In addition, the digital-to-analog converter 100 of the present embodiment adopts the voltage generating module 130 to generate the substrate voltages of the switching transistors SM0, SM1, SM2, SM3 and SM4 in the switching network 120 to obtain the substrate voltages with fixed potentials, so that the voltage value of the substrate voltages of the switching transistors does not change along with the switching of the switches, and meanwhile, the voltage on the resistor string in the digital-to-analog converter is not affected. Therefore, the digital-to-analog converter has good consistency of spike voltage generated during switching of the switch under different conditions, and does not change along with the change of the transmission voltage value. Meanwhile, by adjusting the relation between the resistor in the voltage generation module and the resistor of the resistor string of the digital-to-analog converter, when the external environment (such as power supply voltage, reference voltage, temperature, process angle and the like) changes, the substrate voltage of the switching tube and the voltage to be transmitted can have corresponding proportion changes, so that the reliability of the circuit is further improved.

Fig. 4 and 5 are schematic structural diagrams of a current mode digital-to-analog converter according to a second embodiment of the present application. As shown in fig. 4 and 5, the digital-to-analog converter 300 includes a current source network 310, a switching network 320, and a voltage generation module 330.

The current source network 310 includes a plurality of current sources, as shown in fig. 4 and 5, and the current source network 310 of the present embodiment includes current sources I1-I5, with current magnitudes of I/32, I/16, I/8, I/4, I/2 in order. The switching network 320 includes switching transistors SM0, SM1, SM2, SM3, and SM4, and a first path terminal of the switching transistors SM0, SM1, SM2, SM3, and SM4 is connected to the anodes of the current sources I1 to I5, and a second path terminal is connected to the analog signal output terminal. The cathodes of the current sources I1-I5 are connected to a supply voltage Vdd.

The voltage generation module 330 is configured to obtain a plurality of first voltages according to the reference voltage Vref, where the first voltages are used to provide substrate voltages to the switching transistors SM0, SM1, SM2, SM3, and SM 4. The voltage generation module 330 includes a plurality of resistors Rc1-Rc9 connected in series between the reference voltage Vref and ground, wherein the resistors Rc2-Rc8 have equal resistance values, and the resistors Rc1 and Rc9 have equal resistance values and are half of the resistors Rc2-Rc 8. The resistors Rc1 to Rc9 have connection terminals at both ends, for example: the resistor Rc1 has a terminal Q1 and a terminal Q2 at both ends, the resistor Rc2 has a terminal Q2 and a terminal Q3, the resistor Rc3 has a terminal Q3 and a terminal Q4, the resistor Ra4 has a terminal Q4 and a terminal Q5, and so on, as shown in fig. 4 and 5. The connection terminals at both ends of the resistors Rc1 to Rc9 are used for corresponding connection with the substrates of the switching transistors SM0, SM1, SM2, SM3, and SM4 in the switching network 320. The resistors Rc1-Rc9 are used to generate a substrate voltage corresponding to the switching tube at both ends thereof in response to the current fed by the reference voltage Vref.

The voltage values obtained by the voltage generation module 330 may cover the voltage values transmitted by all the switching tubes in the switching network 320 in the digital-to-analog converter 300, and these voltages may be used as the substrate voltages of the switching tubes SM0, SM1, SM2, SM3 and SM4 in the switching network 320. Specifically, as shown in fig. 4, substrates of switching transistors SM0, SM1, SM2, SM3, and SM4 of an NMOS structure are connected to terminals Q1, Q3, Q5, Q7, and Q9, respectively; in another configuration, as shown in fig. 5, substrates of switching transistors SM0, SM1, SM2, SM3, and SM4 of PMOS structures are connected to terminals Q2, Q4, Q6, Q8, and Q10, respectively. The terminals Q1, Q3, Q5, Q7 and Q9 respectively provide first voltage values for the substrate voltages of the NMOS structure switching transistors SM0, SM1, SM2, SM3 and SM4 respectively; terminals Q2, Q4, Q6, Q8 and Q10 provide second voltage values to PMOS structure switching transistors SM0, SM1, SM2, SM3 and SM4, respectively, for the substrate voltages of PMOS structure switching transistors SM0, SM1, SM2, SM3 and SM4, respectively.

The digital-to-analog converter 300 of the present embodiment further includes a voltage generating module 330, configured to generate a substrate voltage of the switching tube in the switching network 320, so that normal conduction of all the switches is ensured, and the threshold voltage of the switch is not too large, so that the on-resistance of the switch is increased; meanwhile, the area and parasitic capacitance of the switch are not increased, so that large spike voltage cannot occur in the switching process of the switch, and the reliability of the digital-to-analog converter can be further improved.

Fig. 6 and 7 show a schematic structure of a digital-to-analog converter according to a third embodiment of the present application. In the digital-to-analog converter of the low-order number shown in the first and second embodiments, the number of bits of the digital-to-analog converter is low, and thus the number of switching transistors required in the digital-to-analog converter is also small. As the number of bits of the digital-to-analog converter increases, the number of switching transistors increases, and if the substrate voltage is separately provided for each switching transistor in the first and second embodiments, the complexity of the circuit structure of the voltage generation module increases, and the complexity of the logic circuit of the digital-to-analog converter increases.

In the digital-to-analog converter of the third embodiment of the application, therefore, a plurality of switching tubes in the switching network are grouped, and different switching tubes in the same group use the same substrate voltage. As shown in fig. 6 and 7, the digital-to-analog converter 400 includes a resistor string 410, a switching network 420, and a voltage generation module 430. Resistor string 410 includes resistors Ra1-Ra16 connected in series between reference voltage Vref and ground, each having a connection terminal at each end, for example: resistor Ra1 has terminals T1 and T2 at both ends, resistor Ra2 has terminals T2 and T3, resistor Ra3 has terminals T3 and T4, resistor Ra4 has terminals T4 and T5, and so on.

The switching network 420 includes switching transistors SM0 to SM16, and the switching transistors SM0 to SM16 are connected to a plurality of connection terminals in the resistor string 410. For example, the first path ends of the switching transistors SM0 to SM16 are connected to the terminals T1 to T17, respectively, and the second path ends are connected to the analog signal output ends.

The on and off states of the switching tubes SM0 to SM16 are controlled by control signals generated by the decoding circuit.

The switching transistors SM0 to SM16 in the present embodiment may be implemented by Metal-Oxide-semiconductor field effect transistors (MOSFETs), which are not limited thereto, and may be selected by those skilled in the art according to specific situations.

In this embodiment, the switching transistors SM0 to SM16 are exemplified as MOS transistor structures. As shown in fig. 6, the switching transistors SM0 to SM16 are NMOS transistors; alternatively, as shown in fig. 7, the switching transistors SM0 to SM16 are PMOS transistors.

The voltage generation module 430 is configured to obtain a plurality of first voltages according to the reference voltage Vref, where the first voltages are used to provide substrate voltages to the switching transistors SM0 to SM 16. Further, the voltage generating module 430 includes resistors Rc1-Rc4 connected in series between the reference voltage Vref and ground, the resistors Rc1-Rc4 have equal resistance values, and both ends of the resistors Rc1-Rc4 have connection terminals, for example, both ends of the resistor Rc1 have a terminal Q1 and a terminal Q2, respectively, the resistor Rc2 has a terminal Q2 and a terminal Q3, the resistor Rc3 has a terminal Q3 and a terminal Q4, and the resistor Rc4 has a terminal Q4 and a terminal Q5, as shown in fig. 6 and 7.

The resistors Rc1-Rc4 are used to generate a first voltage value and a second voltage value for the switching network 420 across each resistor in response to the current fed by the reference voltage Vref.

In the present embodiment, the switching transistors SM0 to SM16 in the switching network 420 are grouped, and as shown in fig. 6 and 7, the switching transistors SM0 to SM3 are grouped into a first group, the switching transistors SM4 to SM7 are grouped into a second group, the switching transistors SM8 to SM11 are grouped into a third group, and the switching transistors SM12 to SM16 are grouped into a fourth group. Specifically, for a switching network adopting an NMOS structure, terminal Q1 provides a substrate voltage to a first group of switching transistors, terminal Q2 provides a substrate voltage to a second group of switching transistors, terminal Q3 provides a substrate voltage to a third group of switching transistors, and terminal Q4 provides a substrate voltage to a fourth group of switching transistors, as shown in fig. 6; for a switching network employing a PMOS structure, the substrate voltage is provided to the first set of switching tubes by terminal Q2, the substrate voltage is provided to the second set of switching tubes by terminal Q3, the substrate voltage is provided to the third set of switching tubes by terminal Q4, and the substrate voltage is provided to the fourth set of switching tubes by terminal Q5, as shown in fig. 7.

In the preferred embodiment of the application, for the digital-to-analog converter with higher digits, the voltage value difference between the resistors in the resistor string of the digital-to-analog converter is smaller, so that a plurality of switching tubes in a switching network can be grouped, and different switching tubes in the same group use the same substrate voltage, thereby ensuring the normal conduction of all the switching tubes, avoiding the threshold voltage of the switching tubes from being too large and increasing the on resistance of the switching tubes; meanwhile, the circuit complexity of the voltage generation module is not increased, and the logic complexity of the digital-to-analog converter is not increased.

The "resistor" mentioned in the above embodiments may be a single physical resistor or a resistive element, or may be a combination of a plurality of physical resistors or resistive elements. In other words, the resistive digital-to-analog converter shown in the present application is applicable to various types of impedance elements, each of which has an impedance corresponding to a desired resistance. Thus, reference herein to "resistance" is further to any number of different types of resistive elements, such as precision thin film resistors, formed of SiCr or other materials, or in the case of integrated circuits, of (doped p-or n-) polysilicon, depending on the circuit layout. It will also be appreciated that the "resistor" described herein may include any circuit element that may generate a voltage across its terminals that is proportional to the current through it.

In the above embodiment, the voltage generating module is structured as a resistor string. Alternatively, the voltage generation module may be other circuit structures for implementing multiple voltage outputs.

In addition, for convenience of explanation, in the above-described embodiment, the switch network of PMOS structure and the switch network of NMOS structure are separately explained. However, in practical applications, the switch network generally includes both PMOS and NMOS transistors. Therefore, the technical scheme disclosed by the application is also suitable for the switch network with the structure.

It should be noted that the foregoing embodiments only show preferred embodiments, and the grouping manner of the switching transistors in the switching network and the selection method of the substrate voltage are not limited to the foregoing embodiments, and other embodiments applying the same principles are all within the scope of the present application.

In summary, the voltage generating module is used for generating the substrate voltages of the plurality of switches in the switch network, so that normal conduction of all the switches is ensured, the threshold voltage of the switches is not too large, and the on-resistance of the switches is increased; meanwhile, the area and parasitic capacitance of the switch are not increased, and large spike voltage is not generated in the switching process of the switch.

It should be noted that in this document relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

Embodiments in accordance with the present application, as described above, are not intended to be exhaustive or to limit the application to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the application and the practical application, to thereby enable others skilled in the art to best utilize the application and various modifications as are suited to the particular use contemplated. The application is limited only by the claims and the full scope and equivalents thereof.

Claims

1. A digital-to-analog converter, comprising:

a second resistor string including a plurality of third resistors connected between a reference voltage and a reference ground;

a switching network comprising a plurality of switching transistors for selecting at least one third resistor in the second resistor string according to an input digital signal to generate an analog signal corresponding to the digital signal,

a voltage generation module comprising a first resistor string connected in series between a reference voltage and ground, the first resistor string being for deriving a plurality of first voltages from the reference voltage,

wherein the substrates of the plurality of switching tubes are spaced apart from each other, and the first voltage is used to provide a substrate voltage to the switching tubes.

2. The digital-to-analog converter according to claim 1, wherein the plurality of switching transistors are connected as a multi-stage switching transistor, and the voltage value of the analog signal increases with the number of stages of the switching transistor.

3. The digital-to-analog converter according to claim 2, wherein the number of the plurality of first voltages is equal to the number of the switching transistors, each of the first voltages supplying the substrate voltage to the switching transistor corresponding thereto.

4. The digital-to-analog converter of claim 2, wherein a number of the plurality of first voltages is less than a number of the switching transistors, each of the first voltages providing the substrate voltage to a plurality of the switching transistors.

5. The digital-to-analog converter of claim 1, wherein said first resistor string comprises a plurality of first and second resistors connected in series,

the first resistor is connected to the head end and the tail end of the first resistor string, and the second resistor is located in the middle of the first resistor string.

6. The digital to analog converter of claim 5, wherein a resistance of said first resistor is one half a resistance of said second resistor.

7. Digital-to-analog converter according to claim 1, characterized in that the plurality of switching tubes are selected from NMOS tubes and/or PMOS tubes.

8. The digital-to-analog converter of claim 1, further comprising:

a current source network comprising a plurality of current sources,

the switches of the switch network are used for selecting at least one current source in the current source network according to the digital signal so as to generate an analog signal corresponding to the digital signal.