CN118573199A

CN118573199A - Sectional type resistor string DAC

Info

Publication number: CN118573199A
Application number: CN202410659824.3A
Authority: CN
Inventors: 朱凯; 张瑞桐; 王少沛
Original assignee: KT MICRO Inc
Current assignee: KT MICRO Inc
Priority date: 2024-05-27
Filing date: 2024-05-27
Publication date: 2024-08-30

Abstract

The application provides a segmented resistor string DAC, wherein, in an MSB resistor string, an end node of each resistor is connected with an input end of one switch in an S_K switch group; in the MSB resistor string, the end node of each resistor is simultaneously connected with the input end of one switch in the S_M switch group; the switches in the S_M switch group are all MOS switches, wherein two MOS switches connected with the MSB resistor string through the LSB resistor string can respectively play the roles of the first and last resistors in the LSB resistor string; in the LSB resistor string, an end node of each resistor is connected with an input end of one switch in the S_L switch group; the output end of the S_L switch group is connected with the DAC_out end; the input end of the independent switch is connected with the S_K switch group, and the output end of the independent switch is connected with the DAC_out end. It can be seen that the segmented resistor string DAC is able to reduce the influence of the switch on-resistance of the MSB on linearity.

Description

Sectional type resistor string DAC

Technical Field

The application relates to the technical field of DACs, in particular to a segmented resistor string DAC.

Background

DAC (Digital to analog converter) is a digital to analog converter. The high-precision multichannel DAC has important application in the fields of various communication facilities, signal detection, laser driving and the like.

The resistor string DAC is simple in structure and naturally monotonic, and is a common structure. The N bit resistor string DAC consists of 2-N equivalent series resistors and 2-N switches. As the number of bits of the DAC increases, the required resistor string increases exponentially, and thus a segmented resistor string DAC is produced.

However, in practice it has been found that in current segmented resistance DACs the switch on-resistance of the MSB has a large influence on linearity.

Disclosure of Invention

An object of an embodiment of the present application is to provide a segmented resistor string DAC capable of reducing the influence of the on-resistance of the switch of the MSB on linearity.

The first aspect of the present application provides a segmented resistor string DAC comprising an MSB resistor string, an LSB resistor string, an s_k switch set, an s_m switch set, an s_l switch set and individual switches, wherein,

In the MSB resistor string, an end node of each resistor is connected with an input end of one switch in the S_K switch group;

In the MSB resistor string, the end node of each resistor is simultaneously connected with the input end of one switch in the S_M switch group; the S K switch set and the S M switch set are independent of each other;

The switches in the S_M switch group are all MOS switches;

in the LSB resistor string, an end node of each resistor is connected with an input end of one switch in the S_L switch group;

the output end of the S_L switch group is connected with the DAC_out end;

The input end of the independent switch is connected with the S_K switch group, and the output end of the independent switch is connected with the DAC_out end.

Further, when the segmented resistor string DAC is an N-bit DAC, the MSB resistor string corresponds to an M-bit segmented DAC, and the LSB resistor string corresponds to an L-bit segmented DAC;

Wherein,

N＝M+L。

Further, the MSB resistor string comprises 2 ^M resistors, and the LSB resistor string comprises 2 ^L -1 resistors; the LSB resistor string comprises 2 ^L -3 actual resistors and 2 non-actual resistors which are played by two MOS switches connected with the LSB resistor string.

Further, the s_k switch group has a unique common output.

Further, the S_M switch group has two common outputs.

Further, in the s_m switch group, the switches with even numbers share a first common output terminal, and the switches with odd numbers share a second common output terminal of Guan Gongyong.

Further, the segmented resistor string DAC further comprises a switch control voltage adjustment module, wherein,

The output end of the S_K switch group is connected with the switch control voltage adjustment module;

and the output end of the S_M switch group is connected with the switch control voltage adjusting module.

The switch control voltage adjustment module is used for adjusting the switch voltage in the S_M switch group in a feedback mode based on the voltage of the output end of the S_K switch group and the voltage of the output end of the S_M switch group.

Further, the output end of the S_K switch group is connected with the Msb_vk end of the switch control voltage adjustment module;

The output end of the S_M switch group is connected with the MSB_vl end and the MSB_vh end of the switch control voltage adjusting module.

Further, the switch control voltage adjustment module is specifically configured to receive a first ideal voltage value ideal_vh and a second ideal voltage value ideal_vl, compare differential voltage values based on the voltage of the output end of the s_k switch group, the voltage of the output end of the s_m switch group, the first ideal voltage value ideal_vh and the second ideal voltage value ideal_vl, and feedback and adjust switch voltages in the s_m switch group based on the differential voltage value comparison result.

Further, when any adjacent 2 MOS switches in the s_m switch group are turned on, the effect of the corresponding two unit resistors is equivalent;

The switch control voltage adjustment module adjusts the switch voltage in the S_M switch group so that the on-resistance of the S_M switch group is equivalent to a unit resistance.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and other related drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of a segmented resistor string DAC according to an embodiment of the application.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures. Meanwhile, in the description of the present application, the terms "first", "second", and the like are used only to distinguish the description, and are not to be construed as indicating or implying relative importance.

Example 1

Referring to fig. 1, fig. 1 is a sectional type resistor string DAC according to the present embodiment. Wherein the segmented string DAC comprises an MSB string, an LSB string, an S_K switch group, an S_M switch group, an S_L switch group, and an independent switch, wherein,

In the MSB resistor string, the end node of each resistor is simultaneously connected with the input end of one switch in the S_M switch group; the S_K switch group and the S_M switch group are mutually independent;

The switches in the S_M switch group are all MOS switches;

the output end of the S_L switch group is connected with the DAC_out end;

In this embodiment, when the segmented resistor string DAC is an N-bit DAC, the MSB resistor string corresponds to an M-bit segmented DAC, and the LSB resistor string corresponds to an L-bit segmented DAC; wherein,

N＝M+L。

In this embodiment, the MSB resistor string includes 2 ^M resistors, and the LSB resistor string includes 2 ^L -1 resistors; wherein the LSB resistor string comprises 2 ^L -3 actual resistors and 2 non-actual resistors played by two MOS switches connected with the LSB resistor string and the MSB resistor string. .

In this embodiment, the s_k switch group has a unique common output.

In this embodiment, the s_m switch group has two common output terminals.

In this embodiment, in the s_m switch group, the switches with even numbers share a first common output terminal, and the switches with odd numbers share a second common output terminal Guan Gongyong.

As an alternative embodiment, the segmented resistor string DAC further comprises a switch control voltage adjustment module, wherein,

In this embodiment, the output end of the s_k switch group is connected to the msb_vk end of the switch control voltage adjustment module;

In this embodiment, the switch control voltage adjustment module is specifically configured to receive a first ideal voltage value ideal_vh and a second ideal voltage value ideal_vl, compare differential voltage values based on the voltage of the output end of the s_k switch group, the voltage of the output end of the s_m switch group, the first ideal voltage value ideal_vh and the second ideal voltage value ideal_vl, and adjust the switch voltages in the s_m switch group based on the differential voltage value comparison result in a feedback manner.

In this embodiment, when any adjacent 2 MOS switches in the s_m switch group are turned on, the effect of the corresponding two unit resistors is equivalent;

In this embodiment, the segmented string DAC may be a 16bit segmented string DAC.

In this embodiment, the segmented resistor string DAC is composed of two strings of resistors MSB and LSB; wherein the MSB resistor strings are the same as the number of the traditional structures; the LSB resistor strings are 2 less than the traditional structure;

In this embodiment, the MSB switch plays a role of a unit resistor when turned on; the on-resistance is made to be equivalent to a unit resistance by adjusting the control voltage value thereof;

In this embodiment, there are three sets of switches in total in the segmented resistor string DAC, based on which there are three use cases:

(1) When the DAC output code is 2-time, the S_KN switch is turned on;

(2) When the DAC output code is (2≡K+L), the corresponding two MSB switches S_MN are turned on, and the voltage difference between MSB_vh and MSB_vl should be equal to (2≡N-2)/2≡N 1MSB voltage; then selecting and conducting a corresponding LSB switch S_LN;

the difference between the msb_vh (or msb_lv) voltage and the corresponding msb_vk voltage is ideally 1 LSB voltage;

(3) In the three groups of switches, only one switch is conducted each time when the K series and the L series are conducted, and the on resistance of the switch does not influence the input value (the output is assumed to be a high-resistance load), so that the WL value is small, and the area is small so as to reduce the influence of electric leakage; the M-series switch is also small in size, but its control voltage is determined by a feedback loop.

In this embodiment, the adjustment of the switch control voltage can be achieved by the feedback loop of the switch control voltage adjustment module (i.e., sw_vdd_ctrl module) in fig. 1.

In this embodiment, the input information of the sw_vdd_ctrl module is three node voltages msb_vh, msb_lv and dac_out; specifically, the actual differential pressure value and the ideal differential pressure value (differential_vh and differential_vl) may be used to compare to adjust the switch gate voltage so that the on-resistance of the switch is equal to a unit resistance.

Based on fig. 1, for example, the MSB resistor string may set 64 unit resistors and the LSB resistor string may set 61 resistors. When the LSB resistor string is connected to the MSB resistor string, the two on MOS switches may be respectively regarded as LSB resistors (such as R1L and R63L), that is, the LSB resistor string has 63 resistors, where the 63 resistors include 61 true resistors and 2 resistors that are served by the MOS switches (the s_m switch group will turn on 2 adjacent MOS switches at a time).

It can be seen that implementing the segmented resistor string DAC described in this embodiment can reduce the influence of the on-resistance of the switch of the MSB on linearity; when different MSB switches are selected, the problem that the equivalent resistance value is greatly changed due to voltage change is avoided; when the high-voltage power supply is used for outputting high voltage, the problem that the linearity is seriously affected due to the fact that the equivalent resistance of a switch is large caused by a body effect can be avoided.

In addition, functional modules in the embodiments of the present application may be integrated together to form a single part, or each module may exist alone, or two or more modules may be integrated to form a single part.

The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and variations will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

It is noted that 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.

Claims

1. A segmented resistor string DAC, wherein the segmented resistor string DAC comprises an MSB resistor string, an LSB resistor string, an S_K switch group, an S_M switch group, an S_L switch group and independent switches, wherein,

The switches in the S_M switch group are all MOS switches;

the output end of the S_L switch group is connected with the DAC_out end;

2. The segmented resistor string DAC of claim 1 wherein when the segmented resistor string DAC is an N-bit DAC, the MSB resistor string corresponds to an M-bit segmented DAC and the LSB resistor string corresponds to an L-bit segmented DAC; wherein,

N＝M+L。

3. The segmented resistor string DAC of claim 2 wherein the MSB resistor string comprises 2 ^M resistors and the LSB string comprises 2 ^L -1 resistors; the LSB resistor string comprises 2 ^L -3 actual resistors and 2 non-actual resistors which are played by two MOS switches connected with the LSB resistor string.

4. The segmented resistor string DAC of claim 1 wherein the s_k switch set has a unique common output.

5. The segmented resistor string DAC of claim 1 wherein the set of s_m switches has two common outputs.

6. The segmented resistor string DAC of claim 5 wherein the even numbered switches in the s_m switch bank share a first common output and the singular numbered switches Guan Gongyong share a second common output.

7. The segmented resistor string DAC of claim 1 wherein the segmented resistor string DAC further comprises a switch control voltage adjustment module, wherein,

8. The segmented resistor string DAC of claim 7 wherein the output terminals of the s_k switch bank are connected to the msb_vk terminals of the switch control voltage adjustment module;

9. The segmented resistor string DAC of claim 7 wherein the switch control voltage adjustment module is specifically configured to receive a first ideal voltage value ideal_vh and a second ideal voltage value ideal_vl, perform a voltage difference value comparison based on the voltage at the output terminal of the s_k switch group, the voltage at the output terminal of the s_m switch group, the first ideal voltage value ideal_vh and the second ideal voltage value ideal_vl, and then feedback adjust the switch voltages in the s_m switch group based on the voltage difference value comparison result.

10. The segmented resistor string DAC of claim 7 wherein any adjacent 2 MOS switches in the s_m switch set when turned on correspond to the effects of corresponding two unit resistors;