A low temperature drift current mode digital to analog converter and integrated circuit

Abstract

This invention provides a low-temperature drift current-type digital-to-analog converter and integrated circuit, relating to the field of integrated circuits. A reference current generation module, based on curvature compensation, generates a zero-temperature drift current and transmits it as a clamping voltage to a thermometer code switching current array module and a binary code switching current array module. The thermometer code switching current array module performs coarse quantization based on the high-bit code value to generate a coarse-quantized current; the binary code switching current array module performs fine quantization based on the low-bit code value to generate a fine-quantized current. The sum of the coarse-quantized current and the fine-quantized current forms the low-temperature drift analog current and is output. This invention uses a curvature-compensated bandgap reference source to generate a zero-temperature drift current, significantly reducing temperature drift; it employs segmented quantization to achieve high-precision digital-to-analog conversion, ensuring good monotonicity; and it uses partial binary code to replace the lower bits in the thermometer code, greatly reducing the layout area without compromising monotonicity, and simplifying the digital control circuit.

Description

Technical Field

[0001] This invention relates to the field of integrated circuits, and more particularly to a low-temperature drift current-type digital-to-analog converter and integrated circuit. Background Technology

[0002] A digital-to-analog converter (DAC) is a device that converts digital signals into analog signals, serving as the interface between a digital processor and the external world. DACs involve the generation of analog quantities, the accuracy of which is related to the number of bits in the input digital signal and is also affected by various external conditions such as temperature. To reduce the converter's nonlinearity, its reference source module and quantization module require precise design.

[0003] In bandgap reference source design, linear temperature drift compensation and quadratic temperature drift compensation are commonly used. Quantization modules often combine the advantages of encoding methods such as thermometer codes and binary codes, employing a segmented design. However, current bandgap reference source designs still have limited compensation effectiveness for higher-order temperature drift quantities, and segmented quantization circuits still suffer from drawbacks such as low effective accuracy, large layout area, and complex control circuitry.

[0004] Therefore, there is an urgent need to propose a digital-to-analog converter that achieves high accuracy at low temperatures while having a small layout area and simple control circuitry. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide a low-temperature drift current-type digital-to-analog converter and integrated circuit that solves or partially solves the above problems.

[0006] The first aspect of this invention provides a low-temperature drift current-type digital-to-analog converter, which includes: a reference current generation module, a thermometer code switch current array module, and a binary code switch current array module;

[0007] The reference current generation module generates a zero-temperature drift current based on curvature compensation and transmits it to the thermometer code switch current array module and the binary code switch current array module in the form of clamping voltage.

[0008] The thermometer code switch current array module performs coarse quantization based on the high-bit code value to generate a coarse quantized current.

[0009] The binary code switching current array module performs fine quantization based on the low-bit code value to generate finely quantized current.

[0010] The sum of the coarse current and the fine current forms a low-temperature drift simulation current and is output.

[0011] Optionally, the reference current generating module includes: a PTAT current generating unit, a curvature compensation unit, and a reference output unit;

[0012] The PTAT current generating unit is connected to the reference output unit and is used to generate a quasi-PTAT current with linear temperature drift compensation.

[0013] The curvature compensation unit is connected to the PTAT current generating unit and is used to generate a curvature compensation current to compensate for the high-order temperature drift of the quasi-PTAT current generated by the PTAT current generating unit.

[0014] The reference output unit is connected to the thermometer code switch current array module and the binary code switch current array module respectively, and is used to generate the clamping voltage based on the zero temperature drift current.

[0015] Optionally, the curvature compensation unit includes: a first resistor, a second resistor, a third resistor, a first operational amplifier, a first transistor, a second transistor, a first triode, and a second triode; the reference output unit includes: a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a second operational amplifier, a third transistor, a fourth transistor, and a third triode.

[0016] The first terminal of the first resistor, the first terminal of the third transistor, and the first terminal of the fifth resistor all receive power supply voltage;

[0017] The second end of the first resistor is connected to the first end of the first transistor and the first end of the second transistor, and the inverting input of the first operational amplifier, respectively. The non-inverting input of the first operational amplifier receives the clamping voltage.

[0018] The second terminals of the first transistor and the second transistor are each connected to the output terminal of the first operational amplifier;

[0019] The third terminal of the first transistor is connected to the emitter of the first transistor, and the third terminal of the second transistor is connected to the emitter of the second transistor;

[0020] The base and collector of the first transistor are connected to ground, the base of the second transistor is connected to the emitter of the first transistor, and the collector of the second transistor is grounded.

[0021] The emitter of the second transistor is connected to the PTAT current generating unit through the second resistor and the third resistor;

[0022] The second terminal of the third transistor is connected to the PTAT current generating unit, and the third terminal is connected to the non-inverting input of the second operational amplifier and the first terminal of the fourth resistor, respectively.

[0023] The second end of the fourth resistor is connected to the emitter of the third transistor, and the base is connected to the collector and then grounded.

[0024] The second end of the fifth resistor is connected to the first end of the fourth transistor, and outputs the clamping voltage;

[0025] The second terminal of the fourth transistor is connected to the output terminal of the second operational amplifier, and the inverting terminal of the second operational amplifier is connected to the third terminal of the fourth transistor and the first terminal of the sixth resistor, respectively.

[0026] The sixth resistor and the seventh resistor are connected in series to form a zero-temperature-drift resistor and are grounded.

[0027] Optionally, the thermometer code switch current array module includes: a fifth transistor, a single-select switch array, a third operational amplifier, and a resistor array;

[0028] When the high-order bit value is M bits, the number of single-selection switches in the single-selection switch array is 2. M-2 +1, the number of resistors in the resistor array is 2. M-2 +1;

[0029] The resistor array includes an eighth resistor, a ninth resistor, and multiple unit resistors. The resistance of the eighth resistor is twice the resistance of the ninth resistor and four times the resistance of the multiple unit resistors.

[0030] Each resistor in the resistor array receives a power supply voltage at one end, and the other end of each resistor is connected to one end of a single-selection switch in the single-selection switch array.

[0031] The other end of each single-selector switch in the array is connected to the inverting input of the third operational amplifier and the first end of the fifth transistor;

[0032] The non-inverting input of the third operational amplifier receives the clamping voltage, and its output is connected to the second terminal of the fifth transistor. The third terminal of the fifth transistor outputs the coarse current.

[0033] Optionally, the binary code switch current array module includes: multiple transistors of the same size, a single-choice switch, a 2-to-1 switch array, a fourth operational amplifier, and a tenth resistor.

[0034] The first end of the tenth resistor receives the power supply voltage, and the second end is connected to the first end of all transistors and the inverting input of the fourth operational amplifier.

[0035] The non-inverting input of the fourth operational amplifier receives the clamping voltage, and its output is connected to the second terminal of all transistors.

[0036] When the low-order code value is L bits, there are a total of 2 L 2 transistors, LExcept for one transistor whose third terminal is directly connected to the negative output terminal via the single-choice switch, the remaining transistors are divided into L groups. The third terminal of each group of transistors is connected to the stationary terminal of one of the two-to-one switches in the two-to-one switch array.

[0037] Of the two moving terminals of the two-to-one switch, one moving terminal is connected to the negative output terminal, and the other moving terminal outputs the refined current.

[0038] The number of transistors in each group is 2. L-1 ...2 1 2 0 indivual.

[0039] Optionally, the thermometer code switch current array module further includes: a thermometer code decoder;

[0040] When the high-order code value is M bits, the code value of M-2 bits is input into the thermometer code decoder for decoding to obtain the control code. The control code is used to control the single-selection switch connected to multiple unit resistors.

[0041] The two code values ​​other than the M-2 bit code value control the two switches connected to the eighth resistor and the ninth resistor, respectively.

[0042] Optionally, when the high-order code value is M bits, the control code to be decoded is divided into rows and columns of M / 2 bits each, and two M / 2-bit thermometer code decoders are used for decoding.

[0043] Optionally, when the low-order code value is L bits, the L-bit code value is used to control each of the two-to-one switches in the two-to-one switch array, so that each two-to-one switch is connected to the negative output terminal or outputs the fine-quantization current.

[0044] Optionally, the type of the fifth resistor is the same as the type of the eighth resistor in the thermometer code switch current array module and the type of the tenth resistor in the binary code switch current array module, and the resistance value of the eighth resistor is the same as the resistance value of the tenth resistor.

[0045] A second aspect of the present invention provides an integrated circuit, the integrated circuit including a low-temperature drift current-type digital-to-analog converter as described in any of the first aspects above.

[0046] The low-temperature drift current-type digital-to-analog converter provided by this invention includes: a reference current generation module, a thermometer code switch current array module, and a binary code switch current array module. The reference current generation module generates a zero-temperature drift current based on curvature compensation and transmits it to the thermometer code switch current array module and the binary code switch current array module in the form of a clamping voltage.

[0047] The thermometer code switch current array module performs coarse quantization based on the high-bit code value to generate a coarse quantized current; the binary code switch current array module performs fine quantization based on the low-bit code value to generate a fine quantized current; the sum of the coarse quantized current and the fine quantized current forms the low-temperature drift analog current and is output.

[0048] The low-temperature drift current-type digital-to-analog converter proposed in this invention differs from traditional reference source modules and quantization modules. It uses a curvature-compensated bandgap reference source to generate zero-temperature drift current, significantly reducing temperature drift compared to linear and quadratic temperature drift compensation. High-precision digital-to-analog conversion is achieved through coarse and fine segment quantization, with the coarse and fine quantization currents ensuring good monotonicity. Local binary codes are used to directly control branch switches, replacing the lower bits in the thermometer code. This significantly reduces the number of units directly controlled by the thermometer code, simplifying the decoding circuit structure. While maintaining monotonicity, the layout area is greatly reduced, and the digital control circuit is also simplified, resulting in high practicality. Attached Figure Description

[0049] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a schematic diagram of the overall structure of a low-temperature drift current type digital-to-analog converter according to an embodiment of the present invention;

[0051] Figure 2 This is a circuit diagram of a preferred reference current generating module in an embodiment of the present invention;

[0052] Figure 3 This is a circuit diagram of a preferred thermometer code switch current array module in an embodiment of the present invention;

[0053] Figure 4 This is a circuit diagram of a preferred binary code switching current array module in an embodiment of the present invention. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] The present invention proposes a low-temperature drift current-type digital-to-analog converter comprising: a reference current generation module, a thermometer code switching current array module, and a binary code switching current array module. The reference current generation module generates a zero-temperature drift current based on curvature compensation and transmits it to the thermometer code switching current array module and the binary code switching current array module in the form of a clamping voltage.

[0056] The thermometer code switch current array module performs coarse quantization based on the high-bit code value to generate a coarse quantized current; the binary code switch current array module performs fine quantization based on the low-bit code value to generate a fine quantized current; the sum of the coarse quantized current and the fine quantized current forms the low-temperature drift analog current and is output.

[0057] To better illustrate the low-temperature drift current-type digital-to-analog converter proposed in this invention, refer to... Figure 1 The diagram shows the overall structure of a low-temperature drift current type digital-to-analog converter according to an embodiment of the present invention. Figure 1 The dashed box 10 on the left represents the reference current generation module, the dashed box 20 in the middle represents the thermometer code switch current array module, and the dashed box 30 on the right represents the binary code switch current array module.

[0058] Figure 1 China V DD Indicates power supply voltage, V SS This indicates grounding, and V0(T) represents the clamping voltage. The digital code M+L is divided into high-order M bits and low-order L bits by a latch, which are used to control the switch arrays in the thermometer code switch current array module and the binary code switch current array module, respectively. V CM Indicates the negative output level, I c I represents the coarse-quantized current. f I represents the finer quantization current. OUT This represents the simulated current under low temperature drift. V G This indicates the gate voltage of multiple transistors in the control binary code switching current array module, 2 1 2 -2 2 -L These represent the current multiples flowing through each group of transistors.

[0059] The low-temperature drift current-type digital-to-analog converter proposed in this invention generally consists of a reference current generation module based on curvature compensation, which, in conjunction with a 1T1R array, generates several extremely low-temperature drift currents. These currents are then coarsely quantized by a high-bit thermometer code switching current array module and finely quantized by a low-bit binary code switching current array module, ultimately forming a stable low-temperature drift analog current output.

[0060] In some possible embodiments, the reference current generation module includes: a PTAT current generation unit, a curvature compensation unit, and a reference output unit; the PTAT current generation unit is connected to the reference output unit and is used to generate a quasi-PTAT current with linear temperature drift compensation. The curvature compensation unit is connected to the PTAT current generation unit and is used to generate a curvature compensation current to compensate for the high-order temperature drift of the quasi-PTAT current generated by the PTAT current generation unit.

[0061] The reference output unit is connected to the thermometer code switch current array module and the binary code switch current array module respectively. The reference output unit is used to generate clamping voltage based on zero temperature drift current.

[0062] To better illustrate the reference current generating module proposed in this invention, refer to... Figure 2 The diagram shows a circuit schematic of a preferred reference current generating module in an embodiment of the present invention. Figure 2 The leftmost part A represents the curvature compensation unit, the middle part B represents the PTAT current generation unit, and the rightmost part C represents the reference output unit.

[0063] The PTAT current generating unit adopts a conventional PTAT current generating structure. Figure 2 An exemplary circuit structure is shown below, without further details. Furthermore, Figure 2 , 3 The examples in sections 4 and 5 use specific PMOS and NMOS transistors as examples, but this does not mean that they can only be PMOS or NMOS transistors. Any component or circuit structure with the same function can be replaced.

[0064] Figure 2 As shown: Curvature compensation unit A includes: a first resistor R4 and a second resistor R 6a Third resistor R 6b The first operational amplifier A3, the first transistor M7, the second transistor M6, the first transistor Q7, and the second transistor Q6; the reference output unit C includes: the fourth resistor R2, the fifth resistor R0, and the sixth resistor R. 3a The seventh resistor R 3b The second operational amplifier is A2, the third transistor is M5, the fourth transistor is M8, and the third transistor is Q5.

[0065] The first terminal of the first resistor R4, the source of the third transistor Q5, and the first terminal of the fifth resistor R0 all receive the power supply voltage V. DD The second end of the first resistor R4 is connected to the source of the first transistor M7 and the second transistor M8, respectively, and the inverting input of the first operational amplifier A3. The non-inverting input of the first operational amplifier A3 receives the clamping voltage V0(T).

[0066] The gates of the first transistor M7 and the second transistor M8 are both connected to the output terminal of the first operational amplifier A3; the drain of the first transistor M7 is connected to the emitter of the first transistor Q7, and the third terminal of the second transistor M8 is connected to the emitter of the second transistor Q6.

[0067] The base and collector of the first transistor Q7 are connected to ground. SS The base of the second transistor Q6 is connected to the emitter of the first transistor Q7, and the collector of the second transistor Q6 is grounded. SS The emitter of the second transistor Q6 is connected to the second resistor R. 6a Third resistor R 6b Connect to PTAT current generating unit B.

[0068] The gate of the third transistor Q5 is connected to the PTAT current generating unit (i.e., connected to the gates of the four transistors M1 to M4 in the PTAT current generating unit), and the drain of the third transistor Q5 is connected to the non-inverting input of the second operational amplifier A2 and the first end of the fourth resistor R2, respectively.

[0069] The second terminal of the fourth resistor R2 is connected to the emitter of the third transistor Q5, and the base and collector of the third transistor Q5 are connected to ground. SS The second terminal of the fifth resistor R0 is connected to the drain of the fourth transistor M8, and outputs a clamping voltage V0(T).

[0070] The gate of the fourth transistor M8 is connected to the output of the second operational amplifier A2, and the inverting input of the second operational amplifier A2 is connected to the source of the fourth transistor M8 and the sixth resistor R. 3a The first terminal is connected to the sixth resistor R. 3a With the seventh resistor R 3b When connected in series, a zero-temperature-drift resistor (R) is formed. 3a and R 3b Using resistors with positive and negative temperature coefficients respectively, the two can be connected in series to form a zero-temperature-drift resistor, and grounded V. SS .

[0071] Combination Figure 2 As can be seen from the circuit structure, the PTAT current generating unit mainly utilizes the IT of the bipolar transistor. C -V BE Therefore, the following characteristics exist:

[0072]

[0073] In the above formula, A E J is the collector area. C0 ρ is the collector saturation current density, q is the elementary charge, k is the Boltzmann constant, and T is the absolute temperature.

[0074] Under the same bias current, the emitter voltage satisfies the following formula:

[0075]

[0076] If the collector areas of transistors Q2 and Q4 are N times those of transistors Q1 and Q3, then the current I flowing through resistor R1... P for:

[0077]

[0078] Therefore, the current I flowing through resistor R1 can be determined. P It is proportional to the absolute temperature, i.e., PTAT current.

[0079] Combined with bipolar transistor V BE The temperature characteristics show that:

[0080]

[0081] In the above formula, T r For any fixed temperature, δ is the temperature dependence order of the collector current, and η is a coefficient of mass transfer (CLT) related to the minority carrier mobility in the base region. Temperature coefficient related parameters, V GOr The silicon bandgap width at 0K.

[0082] By combining the above formulas, we can obtain:

[0083] V BE (T)=V GOr -a2T-bT ln T

[0084] Therefore, V BE It exhibits a negative slope linear temperature drift and a higher-order temperature drift term of (-T ln T). The PTAT voltage generated by the PTAT current flowing through the fourth resistor R2 can be used to measure V. BE The negative slope linear temperature drift is compensated, and the compensated voltage V bg as follows:

[0085] V bg =V BE (T)+(I P +I CP R2

[0086] Substituting each item into the list, we have:

[0087] V bg =V GOr +(a1-a2)T-bT ln T+I CP (T)R2

[0088] In the above formula, I CPIf the curvature compensation current generated by the curvature compensation unit has only T ln T as its nonlinear term, then V can be compensated by adjusting the resistor. bg The nonlinear term in the equation is used to obtain the zero-temperature drift voltage V. bg .

[0089] The curvature compensation unit in this invention utilizes the V of a bipolar transistor with PTAT bias and zero temperature drift bias. BE The difference will be compensated. Figure 2 The sixth resistor R 3a and the seventh resistor R 3b Using resistors with positive and negative temperature coefficients respectively, connected in series to form a zero-temperature-drift resistor, the second operational amplifier A2 clamps the voltage across the zero-temperature-drift resistor to be close to V. bg Therefore, the current of the fourth transistor M8 is approximately zero temperature drift current.

[0090] After being clamped by the first operational amplifier A3 and shunted by transistors M6 and M7 of the same size, bipolar transistors Q6 and Q7 are biased with zero temperature drift current, and their V BE In the expression The V of Q1 to Q4 under PTAT current bias BE In the expression, δ = 1. The resistance values ​​R of the second and third resistors are taken. 6a =R 6b =R6, the curvature compensation current I can be calculated. CP for:

[0091]

[0092] Curvature compensation current I CP If only linear temperature drift and the T ln T term temperature drift are included, then according to the previous analysis, V bg I0 is the zero-temperature drift voltage, and I0 is the zero-temperature drift

[0093] The signal output of the reference output unit is a clamping voltage V0(T), which is generated by a zero-temperature-drift current flowing through the fifth resistor R0. Due to the temperature coefficient of resistance, the temperature drift of V0(T) itself is not zero, but after being connected to subsequent circuits, it can be used with a resistor R of the same type as the fifth resistor R0. u Generates a zero-temperature drift current I for coarse and fine segment quantization. u If the fifth resistor R0 = λ - 1 R u The approximate expansion using temperature drift is:

[0094] R0(T)=λ -1 R u (T)=R0(T r )[1+TCP1(TT r )+TCP2(TTr ) 2 ]

[0095] Then we have:

[0096] V0(T)=I0R0(T)=V0(T r )[1+TCP1(TT r )+TCP2(TT r ) 2 ]

[0097] Then at the power supply voltage V DD A resistor R is connected between the clamping voltage V0(T) and the clamping voltage. u When, current I u for:

[0098]

[0099] Therefore, the current I can be determined. u It is also a zero-temperature drift current.

[0100] In summary Figure 1 It can be seen that, Figure 1 The bandgap reference source in the dashed box 10 is... Figure 2 The entire structure to the left of the second operational amplifier A2.

[0101] In this invention, the thermometer code switching current array module is used to achieve high-bit coarse quantization. Taking M-bit conversion as an example, thermometer codes generally require (2 M -1) Current sources. If local binary code is used, the number of current sources can be reduced. After the high M bits of the control signal are decoded, several switches are selected to turn on so that the current flows to the output terminal.

[0102] To better illustrate the thermometer code switch current array module proposed in this invention, refer to... Figure 3 The diagram illustrates a circuit schematic of a preferred thermometer-coded switch current array module according to an embodiment of the present invention. The thermometer-coded switch current array module includes: a fifth transistor M9, a single-selection switch array (…). Figure 3 (shown in dashed box), third operational amplifier A4, and resistor array ( Figure 3 The example uses the resistance value R. u R u / 2、...R u / 4 represents each resistor).

[0103] When the high-order bit value is M bits, taking a 2-bit local binary code replacement as an example, the number of single-selection switches in the single-selection switch array is (2 M-2 +1) , the number of resistors in the resistor array is (2 M-2 +1); the resistor array includes: the eighth resistor ( Figure 3 Chinese Ru ), Ninth resistor ( Figure 3 Chinese R u / 2) and multiple unit resistors ( Figure 3 Chinese R u / 4), the resistance of the eighth resistor is twice that of the ninth resistor, and four times that of the resistance of multiple unit resistors.

[0104] Each resistor in the resistor array receives a power supply voltage V at one end. DD The other end is connected to one end of a single-selection switch in the single-selection switch array; the other end of each single-selection switch in the single-selection switch array is connected to the inverting input of the third operational amplifier A4 and the source of the fifth transistor M9.

[0105] The non-inverting input of the third operational amplifier A4 receives the clamping voltage V0(T). The output of the third operational amplifier A4 is connected to the gate of the fifth transistor M9. The drain of the fifth transistor M9 outputs a coarse quantization current I. c .

[0106] In the thermometer code switch current array module, the current source (the third operational amplifier A4 and the resistor array form a current source) has the same structure as the current source in the binary code switch current array. In order to reduce the layout area, the lower bits in the thermometer code can be implemented with 2 or 4 unit resistors in series to achieve half current or 1 / 4 current, and local binary code control is used.

[0107] Because the number of units directly controlled by the thermometer decoder is significantly reduced, its decoding circuit structure is also simpler. When the high-order code value is M bits, the control code to be decoded is divided into M / 2 bits in each row and column, and two M / 2-bit thermometer code decoders are used for decoding. Taking 8-bit thermometer code decoding as an example, the control code to be decoded is divided into 4 bits in each row and column, and two 4-16 thermometer decoders are used. The decoded (M-2) bits of control code are input into the single-selection switch array, and the remaining two bits control I... u and 2I u The switching on and off of the branch switches yields the total current I of the M-bit thermometer code switch current array. c for:

[0108]

[0109] In the above formula, d i This is the i-th bit of the control code. Scale factor. This module achieves coarse quantization of the reference power supply, with a minimum current output of I. u The accuracy is M bits. The thermometer code switch current array module has inherent monotonicity, which helps to improve accuracy.

[0110] In this invention, the binary code switching current array module is used to implement low-order fine quantization. For a better explanation of the binary code switching current array module proposed in this invention, please refer to... Figure 4 The diagram shows a circuit schematic of a preferred binary code switching current array module in an embodiment of the present invention.

[0111] The binary code switching current array module includes: multiple transistors of the same size, a single-choice switch S, and a two-to-one switch array (…). Figure 4 (shown in the dashed box), the fourth operational amplifier A5, and the tenth resistor ( Figure 4 Similarly, R u (This is indicated by the diagram). Therefore, we can conclude that the type of the fifth resistor R0 is the same as the type of the eighth resistor in the thermometer code switch current array module and the type of the tenth resistor in the binary code switch current array module; the resistance value of the eighth resistor is the same as the resistance value of the tenth resistor. The current source in the binary code switch current array module is formed by the fourth operational amplifier A5, the tenth resistor, and a transistor.

[0112] The first terminal of the tenth resistor receives the power supply voltage V. DD The second terminal is connected to the source of all transistors and the inverting terminal of the fourth operational amplifier A5; the non-inverting terminal of the fourth operational amplifier A5 receives the clamping voltage V0(T), and the output terminal of the fourth operational amplifier A5 is connected to the gate of all transistors.

[0113] When the least significant bit value is L bits, there are a total of 2 L 2 transistors, L Of the transistors, only one transistor ( Figure 4 The drain of the rightmost transistor (with a width-to-length ratio of W / L) is directly connected to the negative output terminal V via a single-selector switch S. CM Apart from the connection, the remaining transistors are divided into L groups, and the drain of each group of transistors is connected to the stationary terminal of a two-to-one switch in the two-to-one switch array.

[0114] Of the two moving terminals of the 2-to-1 switch, one moving terminal is connected to the negative output terminal V. CM Connect, the other moving terminal outputs a finely quantized current I f The number of transistors in each group is 2. L-1 ...2 1 2 0 indivual.

[0115] The L-bit code value is used to control each 2-to-1 switch in the 2-to-1 switch array, so that each 2-to-1 switch is connected to the negative output terminal V. CM Connect or output finely quantized current I f .

[0116] 2 LA pair of identical transistors are connected in parallel at the output of a clamping operational amplifier (i.e., the fourth operational amplifier A5), with their sources connected to the tenth resistor R. u Above. The reference current I is clamped by the operational amplifier. u The transistors are replicated into the binary code switching current array at a certain ratio. Since the gates of all transistors are connected to the op-amp output and the sources are all connected to the tenth resistor R... u ,2 L Transistors of the same size receive the same current in the array. Furthermore, the transistors connected to the 2-to-1 multiplexer array are divided into L groups, with each group containing 2 transistors. L -1 ...2 1 2 0 One, therefore Figure 4 The aspect ratio of the total width of each group of transistors is also 2. L-1 W / L, ...2 1 W / L, 2 0 W / L.

[0117] In the 2-to-1 switch array, each of the 2-to-1 switches is controlled by the lower L bits of the input code value M+L. The circuitry on these switches directs power to the output terminal or is negatively affected by the output terminal V, depending on the switch state. CM DC bias absorption. Fine-grained current I flowing to the output terminal. f for:

[0118]

[0119] Where d i This is the i-th bit of the control code. Scale factor. This binary code switching current array module achieves fine-grained control of the reference power supply, with a minimum current output of [value missing]. The precision is L bits. The binary code switching current array module has a smaller layout area and faster speed.

[0120] In summary, the coarse current I is... c and fine-tuning current I f The effective current output I of the low-temperature drift current type digital-to-analog converter proposed in this invention is... OUT for:

[0121]

[0122] proportionality coefficient The low-temperature drift current-type digital-to-analog converter proposed in this invention achieves quantization of the reference power supply and outputs a low-temperature drift analog current, with a minimum current output of [missing information]. The precision is (M+L) bits.

[0123] Based on the above-described low-temperature drift current-type digital-to-analog converter, this invention also proposes an integrated circuit, which includes any of the low-temperature drift current-type digital-to-analog converters described above.

[0124] Through the above examples, the low-temperature drift current-type digital-to-analog converter provided by the present invention includes: a reference current generation module, a thermometer code switching current array module, and a binary code switching current array module. The reference current generation module generates a zero-temperature drift current based on curvature compensation and transmits it to the thermometer code switching current array module and the binary code switching current array module in the form of a clamping voltage.

[0125] The thermometer code switch current array module performs coarse quantization based on the high-bit code value to generate a coarse quantized current; the binary code switch current array module performs fine quantization based on the low-bit code value to generate a fine quantized current; the sum of the coarse quantized current and the fine quantized current forms the low-temperature drift analog current and is output.

[0126] The low-temperature drift current-type digital-to-analog converter proposed in this invention differs from traditional reference source modules and quantization modules. It uses a curvature-compensated bandgap reference source to generate zero-temperature drift current, significantly reducing temperature drift compared to linear and quadratic temperature drift compensation. High-precision digital-to-analog conversion is achieved through coarse and fine segment quantization, with the coarse and fine quantization currents ensuring good monotonicity. Local binary codes are used to directly control branch switches, replacing the lower bits in the thermometer code. This significantly reduces the number of units directly controlled by the thermometer code, simplifying the decoding circuit structure. While maintaining monotonicity, the layout area is greatly reduced, and the digital control circuit is also simplified, resulting in high practicality.

[0127] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0128] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A low-temperature drift current-type digital-to-analog converter, characterized in that, The low-temperature drift current-type digital-to-analog converter includes: a reference current generation module, a thermometer code switch current array module, and a binary code switch current array module. The reference current generation module generates a zero-temperature-drift current based on curvature compensation and transmits it to the thermometer code switch current array module and the binary code switch current array module in the form of clamping voltage. The thermometer code switch current array module performs coarse quantization based on the high-bit code value to generate a coarse-quantized current. The binary code switch current array module performs fine quantization based on the low-bit code value to generate a fine-quantized current. The sum of the coarse-quantized current and the fine-quantized current forms a low-temperature-drift analog current and is output. The reference current generation module includes a PTAT current generation unit and a curvature compensation unit. The curvature compensation unit includes a first resistor, a second resistor, a third resistor, a first operational amplifier, a first transistor, a second transistor, a first triode, and a second triode. The reference output unit includes a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a second operational amplifier, a third transistor, a fourth transistor, and a third triode. The first terminal of the first resistor, the first terminal of the third transistor, and the first terminal of the fifth resistor all receive the power supply voltage. The second terminal of the first resistor is connected to the first terminal of each of the first and second transistors and the inverting input of the first operational amplifier, respectively. The non-inverting input of the first operational amplifier receives the clamping voltage. The second terminals of each of the first and second transistors are connected to the output terminal of the first operational amplifier. The third terminal of the first transistor is connected to the emitter of the first triode, and the third terminal of the second transistor is connected to the emitter of the second triode. The emitter of the transistor is connected; the base and collector of the first transistor are connected to ground, the base of the second transistor is connected to the emitter of the first transistor, and the collector of the second transistor is grounded; the emitter of the second transistor is connected to the PTAT current generating unit through the second resistor and the third resistor; the second terminal of the third transistor is connected to the PTAT current generating unit, and the third terminal is connected to the non-inverting input of the second operational amplifier and the first terminal of the fourth resistor, respectively; the second terminal of the fourth resistor is connected to the emitter of the third transistor, and the base and collector are connected to ground; the second terminal of the fifth resistor is connected to the first terminal of the fourth transistor and outputs the clamping voltage; the second terminal of the fourth transistor is connected to the output terminal of the second operational amplifier, and the inverting input of the second operational amplifier is connected to the third terminal of the fourth transistor and the first terminal of the sixth resistor, respectively; the sixth resistor and the seventh resistor are connected in series to form a zero-temperature drift resistor and are grounded.

2. The low-temperature drift current-type digital-to-analog converter according to claim 1, characterized in that, The reference current generating module further includes: a reference output unit; The PTAT current generating unit is connected to the reference output unit and is used to generate a quasi-PTAT current with linear temperature drift compensation. The curvature compensation unit is connected to the PTAT current generating unit and is used to generate a curvature compensation current to compensate for the high-order temperature drift of the quasi-PTAT current generated by the PTAT current generating unit. The reference output unit is connected to the thermometer code switch current array module and the binary code switch current array module respectively, and is used to generate the clamping voltage based on the zero temperature drift current.

3. The low-temperature drift current-type digital-to-analog converter according to claim 1, characterized in that, The thermometer code switch current array module includes: a fifth transistor, a single-select switch array, a third operational amplifier, and a resistor array; When the high-order bit value is M bits, the number of single-selection switches in the single-selection switch array is 2. M-2 +1, the number of resistors in the resistor array is 2. M-2 +1; The resistor array includes an eighth resistor, a ninth resistor, and multiple unit resistors. The resistance of the eighth resistor is twice the resistance of the ninth resistor and four times the resistance of the multiple unit resistors. Each resistor in the resistor array receives a power supply voltage at one end, and the other end of each resistor is connected to one end of a single-selection switch in the single-selection switch array. The other end of each single-selector switch in the array is connected to the inverting input of the third operational amplifier and the first end of the fifth transistor. The non-inverting input of the third operational amplifier receives the clamping voltage, and its output is connected to the second terminal of the fifth transistor. The third terminal of the fifth transistor outputs the coarse current.

4. The low-temperature drift current-type digital-to-analog converter according to claim 1, characterized in that, The binary code switching current array module includes: multiple transistors of the same size, a single-choice switch, a 2-to-1 switch array, a fourth operational amplifier, and a tenth resistor. The first end of the tenth resistor receives the power supply voltage, and the second end is connected to the first end of all transistors and the inverting input of the fourth operational amplifier. The non-inverting input of the fourth operational amplifier receives the clamping voltage, and its output is connected to the second terminal of all transistors. When the low-order code value is L bits, there are a total of 2 L 2 transistors, 2 L Except for one transistor whose third terminal is directly connected to the negative output terminal via the single-choice switch, the remaining transistors are divided into L groups. The third terminal of each group of transistors is connected to the stationary terminal of one of the two-to-one switches in the two-to-one switch array. Of the two moving terminals of the two-to-one switch, one moving terminal is connected to the negative output terminal, and the other moving terminal outputs the refined current. The number of transistors in each group is 2. L-1 ...2 1 2 0 indivual.

5. The low-temperature drift current-type digital-to-analog converter according to claim 3, characterized in that, The thermometer code switch current array module also includes: a thermometer code decoder; When the high-order code value is M bits, the code value of M-2 bits is input into the thermometer code decoder for decoding to obtain the control code. The control code is used to control the single-selection switch connected to multiple unit resistors. The two code values ​​other than the M-2 bit code value control the two switches connected to the eighth resistor and the ninth resistor, respectively.

6. The low-temperature drift current-type digital-to-analog converter according to claim 5, characterized in that, When the high-order code value is M bits, the control code to be decoded is divided into M / 2 bits in each row and column, and two M / 2-bit thermometer code decoders are used for decoding.

7. The low-temperature drift current-type digital-to-analog converter according to claim 4, characterized in that, When the low-order code value is L bits, the L-bit code value is used to control each of the two-to-one switches in the two-to-one switch array, so that each two-to-one switch is connected to the negative output terminal or outputs the fine-quantized current.

8. The low-temperature drift current-type digital-to-analog converter according to claim 1, characterized in that, The type of the fifth resistor is the same as the type of the eighth resistor in the thermometer code switch current array module and the type of the tenth resistor in the binary code switch current array module, and the resistance value of the eighth resistor is the same as the resistance value of the tenth resistor.

9. An integrated circuit, characterized in that, The integrated circuit includes a low-temperature drift current-type digital-to-analog converter as described in any one of claims 1-8.

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