A high-precision bandgap reference source circuit based on digital trimming

Abstract

The application relates to an analog integrated circuit technology field, and relates to a high-precision band gap reference source circuit based on digital trimming. In the band gap reference voltage source, a digital trimming resistor array, an adaptive current adjusting driver circuit and a low-offset amplifier circuit are integrated, so that temperature compensation of output voltage, strong band load capacity and low temperature coefficient of output voltage are realized. A temperature sensor outputs a control signal according to different temperatures, and sends the control signal to a digital control and signal processing module, and the digital control and signal processing module is connected with an I 2 C bus communication, and the I 2 C bus reads corresponding trimming codes from a nonvolatile memory and writes the trimming codes into internal digital registers. Then, a level shift circuit reads the trimming codes in the digital registers, and the trimming codes are converted from low voltage in the digital domain into high voltage in the analog domain. The high-voltage trimming codes are transmitted to a resistor array, and the resistor array trims resistors in the band gap reference voltage source according to the current temperature, so that low-offset voltage of the band gap reference voltage source is realized.

Description

Technical Field

[0001] This invention relates to the field of analog integrated circuit technology, and in particular to a high-precision bandgap reference source circuit based on digital tuning. Background Technology

[0002] In integrated circuit design, bandgap voltage references are widely used to provide stable and reliable reference voltages due to their excellent temperature stability and good process compatibility. To achieve optimal system performance, bandgap voltage references typically require high power supply rejection ratios (PSRR) and low temperature coefficients. However, in actual design and testing, factors such as resistor mismatch and ambient temperature variations often lead to discrepancies between simulation results and actual measurements. Optimizing the temperature coefficient largely depends on the matching accuracy of the resistor ratio. Furthermore, with the continuous expansion of integrated circuit scale and the increasing number of on-chip modules, the system's load requirements for reference voltages have significantly increased, placing higher demands on the load-carrying capacity of bandgap voltage references. To provide stable reference voltages for multiple analog and digital sub-modules simultaneously in complex systems, the bandgap voltage reference not only needs stronger driving capability but must also maintain good stability, fast transient response, and high power supply rejection ratio performance under heavy load conditions. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the present invention proposes a high-precision bandgap reference source circuit based on digital adjustment to solve the problems of output voltage deviation and insufficient load-carrying capacity of traditional bandgap reference voltage sources under temperature changes.

[0004] To address the problems of the prior art, the present invention adopts the following technical solution:

[0005] A high-precision bandgap reference source circuit based on digital adjustment is provided, the circuit comprising:

[0006] Temperature sensor, digital control and signal processing module, I 2 C-bus, non-volatile memory, level shifting circuit, digital trimming resistor array, bandgap reference voltage source (except for the non-volatile memory, the rest can be integrated into one chip, which can be fabricated using CSMC 180nm BCD process).

[0007] A temperature sensor monitors the temperature in real time (the monitored temperature can be the temperature of the aforementioned chip). The temperature sensor generates control signals based on different temperatures and sends these control signals to the digital control and signal processing module.

[0008] The digital control and signal processing module, upon receiving a control signal for a given adjustment point, initiates I... 2 C-bus;

[0009] I 2 C bus, the I 2 The C bus interface is used to connect to non-volatile memory. Upon power-up (which could be the power-up of the aforementioned chip), it connects via I... 2 The C interface reads data from non-volatile memory into internal registers, and can only enter the working state after verification;

[0010] Non-volatile memory, wherein the non-volatile memory is used to store adjustment data;

[0011] A level shifting circuit is used to boost the low supply voltage of the digital circuit to the high supply voltage of the analog circuit; the level shifting circuit outputs a boosted modulated code for use by the subsequent decoder. The digital circuit includes I... 2 The system includes a C-bus, digital control and signal processing modules, and non-volatile memory; the analog single-channel circuit includes a temperature sensor, level shifting circuit, digital trimming resistor array, and bandgap reference voltage source. The power supply voltage for digital circuits is typically 1.8V, while the power supply voltage for analog circuits is typically 3.3V. The high-level signal output from the digital section, 1.8V, needs to be boosted to 3.3V to power the analog circuits; the level shifting circuit serves this boosting function.

[0012] A digital trimming resistor array, consisting of a resistor array and a decoder (the specific connection method between the resistor array and the decoder is conventional in the field and will not be described further here), is designed to compensate for the impact of temperature drift on circuit performance. The decoder receives digital codes from the digital control and signal processing module, controls the resistance values ​​in the resistor array, and thus controls the output voltage of the bandgap reference voltage source. A temperature sensor outputs multiple sets of control signals to the digital control and signal processing module at different temperatures. When the digital control and signal processing module receives a control signal corresponding to a specific trimming temperature point, it processes the signal through I... 2 The C bus communicates with the non-volatile memory, reads the corresponding trimming data, and writes it to the internal register. The internal register transmits the trimming data to the level shifting circuit, which converts the trimming data and sends it to the decoder of the digital trimming resistor array.

[0013] A bandgap reference voltage source, which is used to generate a reference voltage Vref.

[0014] Furthermore, the temperature sensor is based on a 16-bit Sigma-Delta ADC architecture. The temperature sensor converts the sensed chip temperature information into a corresponding 16-bit digital temperature code Ku<15:0>. This temperature code has a monotonic correspondence with the operating temperature (which can be the operating temperature of the aforementioned chip), and is used to characterize the current temperature state. It also serves as the input signal for temperature compensation and adjustment control by the digital control and signal processing module.

[0015] The digital control and signal processing module starts the I2C bus when it receives the control signal Ku<15:0> for a given adjustment point.

[0016] Furthermore, the type of non-volatile memory is EEPEOM, FLASH, or PROM implemented based on fuses or antifuse.

[0017] Furthermore, the logic for issuing the digital code is as follows: During operation (which can be the operation of the aforementioned chip), the temperature sensor outputs multiple sets of control signals Ku<15:0> to the digital control and signal processing module at different temperatures. When the digital control and signal processing module receives the control signal corresponding to a certain temperature adjustment point, it uses I... 2 The C bus communicates with the non-volatile memory (which can be an external EEPROM) to read the corresponding trimming data apr<3:0> and svr<3:0> and write it into the internal register. The power supply voltage of the digital circuit is 1.8V, and the power supply voltage of the analog circuit is 3.3V. Therefore, the generated trimming data apr<3:0> and svr<3:0> are 1.8V voltage signals. The internal register transmits the trimming data apr<3:0> and svr<3:0> to the level shifting circuit, which converts the 1.8V trimming data into 3.3V trimming data A<3:0> and S<3:0> for use by the digital trimming resistor array. The 3.3V adjustment data A<3:0> and S<3:0> are transmitted to the decoder in the digital adjustment resistor array. A<3:0> is sent to A3, A2, A1, and A0 of the decoder, respectively, and S<3:0> is sent to A3, A2, A1, and A0 of another identical decoder, respectively. Then, the decoder outputs Y0, Y1, Y2...Y 15 Control switches K0, K1, K2...K respectively 15 This allows for the control of the resistance values ​​in the resistor array. The RL terminal of the digital adjustment resistor array is connected to the node RL of the adjustable resistors R4 and R8 in the bandgap reference voltage source.

[0018] Furthermore, a bandgap reference voltage source is provided, which includes a current mirror structure composed of PMOS transistors M1 and M2. The current mirror structure is used to replicate the startup current and provide a stable bias reference for subsequent circuits.

[0019] It also includes a bias network composed of resistor R1 and transistors Q1 and Q2, which is used to stabilize the DC operating point of the circuit.

[0020] It also includes transistor Q3, which acts as a start-up trigger, and the base voltage V of Q3. st As a key node in the startup logic, node V...st A startup signal of approximately 1.7V is generated, turning on Q3 and providing initial current to Q4 and Q5. This initial current, amplified and driven by the amplifier and driver, pushes the output reference voltage Vref up. Subsequently, Vref is fed back to the bases of Q4 and Q5 through resistors R7 and R8, thus enabling the bandgap core circuit to enter normal operation. After the startup process is complete, Vref stabilizes at 2.5V, turning off Q3, thereby effectively isolating the startup circuit and improving the power supply rejection ratio of the bandgap reference voltage source.

[0021] Furthermore, the level shifting circuit is used to realize the voltage domain conversion of temperature compensation related digital trimming codes, converting the 4-bit trimming codes apr<3:0> and svr<3:0> operating in the 1.8 V voltage domain of the digital circuit into trimming codes A<3:0> and S<3:0> operating in the 3.3 V voltage domain of the analog circuit, and sending them to the subsequent 4-to-16 decoder to control the digital trimming resistor array, thereby realizing temperature compensation and fine trimming of analog circuit parameters.

[0022] Furthermore, the digital adjustment resistor array consists of a resistor array and a 4-16 decoder, designed to compensate for the impact of temperature drift on circuit performance; the 4-16 decoder receives a 4-bit digital code to control the switching of the resistor array, thereby controlling the magnitude of the resistors in the resistor array.

[0023] Furthermore, such as Figure 1 As shown, the core circuit adopts a Brokaw structure. Utilizing the "virtual short" effect of amplifier OP, the voltage at node A (positive input) of amplifier OP is equal to the voltage at node B (negative input). Resistor R2 is connected to node B, and resistor R5 is connected to node A. The resistance values ​​of resistors R2 and R5 are equal, and the currents I1 and I2 are equal. That is: ,in and They are respectively and The voltage between the base and emitter. Transistor. and The emitter area ratio factor N is 8:1. Because... ,in The thermal voltage V at room temperature T≈300K T ≈26mV. Resistance The voltage across the two ends is ,so Base voltage The output voltage Vref of the bandgap reference voltage source is... Base voltage In resistor and The voltage divider, therefore the expression for the output voltage Vref of the bandgap reference voltage source is: .

[0024] Furthermore, the amplifier is a single-pole amplifier employing a folded common-emitter common-base structure. This structure ensures symmetry between the two branches of the common-emitter common-base amplifier, reducing the amplifier's offset voltage.

[0025] Furthermore, such as Figure 4 As shown, the relationship between the output voltage and the input voltage of the driver is as follows: The leakage current of transistor M6 is determined by... and Control, M6 gate connection ,and And by transistor and The base current determines the value. and emitter junction When the transistor and When operating in the amplification region, the change in base current is small, therefore it can be considered that... Drain current Basically unchanged, therefore It also remains unchanged. The only part that has changed is Moreover, the range of variation is limited. Therefore, the output voltage of the driver... It does not produce a voltage amplification effect; it is simply based on the superposition of the input voltage. and This increases the voltage by approximately 1.2V. It can be understood as a voltage follower; its main function is to automatically adjust the voltage of the power transistor based on the load. The output current, source terminal emitter, drain connection , gate connection Collector. This driver can minimize its own current consumption while ensuring an output current of 15mA, thereby improving the bandgap's load-carrying capacity.

[0026] Furthermore, frequency compensation adopts a zero-point compensation method, such as... Figure 1As shown, a compensation circuit is added between the amplifier and the driver, consisting of a resistor R6 and a capacitor C2 connected in series, and then in parallel with a capacitor C1. The compensation circuit uses resistor R6 and capacitor C2 to generate a zero, thereby canceling the poles generated by the driver and load capacitors. Capacitor C1 reduces the amplifier's bandwidth. By introducing an appropriate zero to cancel the low-frequency poles generated by the driver and load capacitors, the system's phase margin and stability are improved. A zero-based compensation method is used between the amplifier and the driver, i.e., a compensation circuit is added between the amplifier and the driver.

[0027] Furthermore, the temperature sensor, digital control and signal processing module, and I... 2 The C-bus, level shifting circuit, digital trimming resistor array, and bandgap reference voltage source are integrated into a single chip, which can be fabricated using CSMC's 180nm BCD process.

[0028] The technical solution adopted in this invention has the following beneficial effects:

[0029] 1. In the design of the bandgap reference voltage source, a temperature sensor is used to monitor the chip temperature in real time and adjust the bandgap output drift.

[0030] 2. In the design of the bandgap reference voltage source, temperature sensors, digital control and signal processing modules, and I / O are utilized. 2 C-bus, non-volatile memory, level shifting circuit, digital trimming resistor array, bandgap reference voltage source, according to Figure 1 The connection shown generates an output voltage Vref across capacitor C2 and resistor R9.

[0031] 3. In the design of the bandgap reference voltage source, a current adaptive driver circuit was added, which can adaptively adjust the output current according to the load conditions, achieving 0.1... F-100 Any load of F.

[0032] 4. Using an amplifier with a folded common-emitter common-base structure can reduce the amplifier's offset voltage, thereby reducing the influence of the temperature coefficient on the bandgap output voltage. Attached Figure Description

[0033] Figure 1 A high-precision bandgap reference voltage source circuit flowchart is provided for this invention;

[0034] Figure 2 This invention provides an amplifier circuit in a bandgap reference voltage source circuit; Figure 2 The IB1 port in Figure 1 Connected to the IB port in the middle. Figure 2 VIP port in Figure 1 Connect to node A in the diagram. Figure 2The VIN port in the middle is connected to node B. Figure 2 VO1 port in Figure 1 The upper end of capacitor C1 in the middle is connected;

[0035] Figure 3 The present invention provides an amplifier core Q9 collector voltage follower V O Simulation results of the changes;

[0036] Figure 4 This invention provides a driver circuit in a bandgap reference voltage source circuit;

[0037] Figure 5 This invention provides a simulation of the output Vref of a bandgap reference voltage source under different load capacitances;

[0038] Figure 6 The power supply rejection ratio simulation results of the bandgap reference voltage source provided by this invention;

[0039] Figure 7 The simulation results show the adjusted temperature coefficient of the bandgap reference voltage source provided by this invention.

[0040] It should be noted that the circuit structure presented in this invention is used to illustrate the system's working principle and design concept. Specific component parameters (such as resistance and capacitance values) are not labeled in the figures. This is because the relevant verification simulations are based on specific process conditions and design goals. The specific parameters belong to the design details at the implementation level and are adjustable under different process nodes, power supply conditions, and performance constraints. Detailed Implementation

[0041] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0042] like Figure 1 As shown, the present invention provides a high-precision reference voltage source circuit based on digital adjustment, comprising:

[0043] A temperature sensor, which can output a 16-bit digital code based on the chip temperature and input it into the digital control and signal processing module circuit;

[0044] The digital control and signal processing module will start the I2C bus when it receives the Ku<15:0> signal with a given adjustment point.

[0045] I 2 C bus, the I 2 The C bus interface is used to connect to non-volatile memory. When the chip is powered on, it connects via I... 2The C interface reads data from non-volatile memory into internal registers, and can only enter the working state after verification;

[0046] Non-volatile memory, which is used to store adjustment data, may be of the type EEPEOM, FLASH, or PROM based on fuses or antifuse;

[0047] A level shifting circuit is used to boost the 1.8V supply voltage of the digital circuit to 3.3V of the analog circuit. Its outputs A<3:0> and S<3:0> are the boosted adjustment codes, used by the subsequent 4–16 decoder. The level shifting circuit can be the level shifting circuit described in patent number 2021216359274, entitled "A Level Conversion Circuit".

[0048] A digital trimming resistor array, consisting of a resistor array and a 4-to-16 decoder, is designed to compensate for the effects of temperature variations on circuit performance. The 4-to-16 decoder receives a 4-bit digital code to control the switching of the resistor array, thereby controlling the values ​​of resistors R4 and R8.

[0049] The bandgap reference voltage source adopts a Brokaw structure for its core bandgap circuit, which includes a startup circuit, a bandgap voltage generation circuit, an amplifier, frequency compensation, and a driver.

[0050] In use, the on-chip temperature sensor generates control signals Ku<15:0> based on different temperatures and sends these signals to the digital control and signal processing module. When the digital control and signal processing module receives a Ku<15:0> signal that matches a given adjustment point, it activates the I2C bus. This module then uses I2C to... 2 The C bus reads the corrected data from non-volatile memory into internal registers, generating control signals apr<3:0> and svr<3:0>. These signals are 1.8V, which are then converted to 3.3V signals A<3:0> and S<3:0> by a level shifting module for use by the adjustment resistor array. The resistor array consists of 17 resistors connected in series, from R1 to R2. 16 It is a switch Y0-Y 15 The circuit is controlled by the fact that when the switch is closed, the resistors are short-circuited, thus reducing the resistance of the series resistors and consequently controlling the values ​​of R4 and R8. R4 and R8 are just abstract symbols; the actual R4 and R8 are represented by a resistor array in the circuit. In the circuit, R4 and R8 are symbols for adjustable resistors, and the TR port in the adjustable resistor array is connected to the TR node in the bandgap reference voltage source.

[0051] The temperature sensor circuit generates control signals based on different temperatures, thereby adjusting the resistance values ​​in the resistor array and controlling the output voltage accuracy of the bandgap reference voltage source.

[0052] The amplifier in the bandgap voltage reference source employs a low-offset, highly symmetrical folded common-emitter common-base structure. The drive module can provide a larger output current while reducing its own current consumption. The output voltage expression of the bandgap voltage reference source proposed in this invention is:

[0053]

[0054] What does VT represent? VT stands for thermal voltage. At room temperature T≈300K, VT≈26mV.

[0055] VBE5 indicates Figure 1 Voltage between the BE terminals of Q5.

[0056] The core of the bandgap reference voltage source adopts a low offset amplifier with a "folded common-emitter common-base" structure, and the two branches of the folded common-emitter common-base amplifier are symmetrical.

[0057] Figure 2 The diagram shows the core of the amplifier circuit used in this invention. This amplifier uses bipolar transistors as its main components, with Q5, Q6, Q7, and Q8 forming a symmetrical folded common-emitter, common-base structure. The gate voltage of transistor M5 is given by the following relationship: Confirmed. Since transistors M6 and M5 use the same size design, the gate voltage of M5 can follow the output V. O Synchronous change. The source voltage of transistor M6 changes from... Confirmed. However, the collector voltage of Q9 does not perfectly follow the output voltage V. O The change, because when V O When the threshold voltage is increased, the absolute value of the gate-source voltage of M6 is less than the absolute value of the threshold voltage, that is... At this time, M6 is in the cutoff region, and the following effect disappears. A characteristic of this amplifier is that the collector voltage of Q9 follows V. O The change in voltage is a measure to reduce offset voltage, because the key factor causing inherent offset in common-emitter common-base amplifiers is the asymmetry between the two branches.

[0058] Figure 3 This is the DC analysis result when the amplifier is configured as a follower, with the voltage at the non-inverting input varying from 0 to 2.7V. The simulation results show that when the amplifier's output voltage is in the range of 0.7-1.7V, the collector voltage of Q9 will follow V... O The amplifier's output voltage will be raised by about 1.2V in the driver, and when the driver's output is about 2.5V, the amplifier's output will fall within this range.

[0059] Figure 4 This refers to the driver circuit in a bandgap reference voltage source circuit. Figure 4 VI port and Figure 1 The upper end of the medium resistor R6 is connected, that is Figure 2 The amplifier's output terminal VO1. Figure 4 VO2 port in Figure 1 The Vref port is connected. M1 and M2 form a current mirror structure, while M3, M4, and M5 form another current mirror structure. The relationship between the driver's output voltage and input voltage is as follows: Among them, the leakage current of M6 is caused by and Control, and And from and The base current determines this. When and When operating in the amplification region, the change in base current is small, therefore it can be considered that... Drain current Basically unchanged, therefore It also remains unchanged. The only part that has changed is Moreover, the range of variation is limited. Therefore, the output voltage of the driver... It does not produce a voltage amplification effect; it is simply based on the superposition of the input voltage. and This increases the voltage by approximately 1.2V. It can be understood as a voltage follower; its main function is to automatically adjust the voltage of the power transistor based on the load. The output current.

[0060] Figure 4 middle and Forming a current mirror structure, The number of m is N times, therefore =N. Current Depend on The BE junction voltage is controlled, and the BE junction voltage is related to... , and The relevant relationship is as follows: .on the other hand, Also a MOSFET The drain voltage, i.e.: . and Forming a current mirror structure, The leakage current is caused by the feedback current. Control. This circuit has a dual feedback relationship. When analyzing the current feedback effect, it is necessary to assume... and All of these remain unchanged, and a static operating point needs to be determined. The unloaded (i.e., The state when disconnected is called the static operating point. Figure 4 middle , .

[0061] Feedback current under no-load conditions Should make Figure 4 In When the maximum allowed value is reached, at this point... ensure pass The current generated after the shunt is exactly equal to This achieves load balancing. Later, due to from Diversion, resulting in Reduce, thus Reduce, this will Ascending, making Increase, or rather, make A decrease is equivalent to an increase. of .therefore, Figure 4 middle Increase the output current to achieve a new equilibrium state.

[0062] Figure 5 The output Vref of the bandgap reference voltage source under different load capacitances shows that the output Vref can reach a stable state under any load capacitance from 0.1μF to 100μF. Figure 5 The simulation results for the power supply rejection ratio (PSRR) of the bandgap reference voltage source show that the PSRR can reach -114.2 dB at low frequencies. Figure 7 The temperature coefficient of the bandgap reference voltage source has been adjusted, with a minimum temperature coefficient reaching 2.372 ppm / ℃. A driver circuit has been added to the core of the bandgap reference voltage source, featuring a dual feedback relationship that allows for arbitrary load capacitance from 0.1 μF to 100 μF.

[0063] This invention aims to control the output voltage Vref of a bandgap reference voltage source to prevent deviation due to temperature changes, and to increase the driving load capability of the bandgap reference voltage source. For potential temperature deviations, this invention utilizes a temperature sensor to generate control signals Ku<15:0> based on different temperatures, and sends these signals to a digital control and signal processing module. When the digital control and signal processing module receives a Ku<15:0> signal matching a given adjustment point, it activates...2 C control module. This module uses 1 2 C reads the corrected data from non-volatile memory into the internal register. Finally, A<3:0> and S<3:0> are applied to switch the resistor array to adjust the output voltage to match the measured temperature. To increase the load capacity of the bandgap reference voltage source, this invention adds an adaptive current regulation driver circuit to the bandgap reference voltage source circuit, which can maintain good stability, transient response, and high power supply rejection ratio performance under heavy load conditions.

[0064] The non-volatile memory can be located on-chip or off-chip. Before the chip leaves the factory, it can be adjusted via the CPU interface to ensure that the bandgap output Vref always meets the required accuracy within the required temperature range. Then, the adjustment data is written to the non-volatile memory. When the chip is powered on later, it first reads data from the non-volatile memory to ensure that A<3:0> and S<3:0> satisfy the relationship during adjustment, thus accurately generating the reference voltage Vref.

[0065] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the solutions disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the claims.

Claims

1. A high-precision bandgap reference voltage source circuit based on digital adjustment, characterized in that... Includes temperature sensor, digital control and signal processing module, I 2 C-bus, non-volatile memory, level shifting circuit, digital trimming resistor array, and bandgap reference voltage source; The temperature sensor monitors the temperature in real time, generates control signals based on different temperatures, and sends these control signals to the digital control and signal processing module. When the digital control and signal processing module receives a control signal for a given adjustment point, it starts I... 2 C-bus; I 2 The C bus interface is used to connect non-volatile memory. Upon power-up, it connects via I... 2 The C interface reads data from non-volatile memory into internal registers, and can only enter the working state after verification; Non-volatile memory is used to store adjustment data; Level shifting circuits are used to boost the low supply voltage of digital circuits to the high supply voltage of analog circuits; the level shifting circuit outputs a boosted modulated code for use by the subsequent decoder; digital circuits include I... 2 C-bus, digital control and signal processing module, non-volatile memory; The analog single channel includes a temperature sensor, a level shifting circuit, a digital trimming resistor array, and a bandgap reference voltage source; The digital trimming resistor array consists of a resistor array and a decoder, compensating for the impact of temperature drift on circuit performance. The decoder receives digital codes from the digital control and signal processing module, controls the resistance values ​​in the resistor array, and thus controls the output voltage of the bandgap reference voltage source. The temperature sensor outputs multiple sets of control signals to the digital control and signal processing module at different temperatures. When the digital control and signal processing module receives the control signal corresponding to a specific trimming temperature point, it processes the signal through I... 2 The C bus communicates with the non-volatile memory, reads the corresponding trimming data and writes it into the internal register; the internal register transmits the trimming data to the level shifting circuit, and the level shifting circuit converts the trimming data and sends it to the decoder of the digital trimming resistor array; A bandgap reference voltage source generates a reference voltage Vref; The bandgap reference voltage source includes a current mirror structure composed of PMOS transistors M1 and M2. The current mirror structure is used to replicate the startup current and provide a stable bias reference for subsequent circuits. It also includes a bias network composed of resistor R1 and transistors Q1 and Q2, which is used to stabilize the DC operating point of the circuit. It also includes transistor Q3, which acts as a start-up trigger, and the base voltage V of Q3. st As a key node in the startup logic; when power is applied, node V... st A 1.7V start-up signal is generated at the point, which turns on Q3 and provides initial current to Q4 and Q5; The initial current, amplified and driven by the amplifier and driver, pushes the output reference voltage Vref up. Subsequently, Vref is fed back to the bases of Q4 and Q5 through resistors R7 and R8, thus enabling the bandgap core circuit to enter normal operation. After the startup process is completed, Vref stabilizes at 2.5V, turning off Q3, isolating the startup circuit, and improving the power supply rejection ratio of the bandgap reference voltage source. V st It is the connection point of the drain of M2, the base of Q3, and one end of R1; The output voltage Vref of the bandgap reference voltage source is Base voltage In resistor and The partial voltage; The sources of M1 and M2 are connected to the collector of Q3. The gates of M1 and M2 are connected. The drain of M2 is connected to the base of Q3 and one end of R1. The other end of R1 is connected to the base and collector of Q1. The emitter of Q1 is connected to the base and collector of Q2. The emitter of Q2 is connected to one end of R8. The other end of R8 is connected to the base of Q4, the base of Q5, and one end of R7. The emitter of Q3 is connected to one end of resistor R2 and one end of resistor R5. The other end of R2 is connected to the collector of Q4, and the other end of R5 is connected to the collector of Q5. The other end of R7 is connected to Vref. Vref is connected to the base and collector of transistor Q6. The emitter of Q6 is connected to the emitter of Q3.

2. The high-precision bandgap reference voltage source circuit based on digital adjustment according to claim 1, characterized in that... The temperature sensor is based on a 16-bit Sigma-Delta ADC architecture. The temperature sensor converts the sensed chip temperature information into a corresponding 16-bit digital temperature code Ku<15:0>. This temperature code has a monotonic correspondence with the operating temperature and is used to characterize the current temperature state. It also serves as the input signal for temperature compensation and adjustment control by the digital control and signal processing module. When the digital control and signal processing module receives the control signal Ku<15:0> for a given adjustment point, it starts the I2C bus.

3. The high-precision bandgap reference voltage source circuit based on digital adjustment according to claim 1, characterized in that... The logic for transmitting the digital code is as follows: During operation, the temperature sensor outputs multiple sets of control signals Ku<15:0> to the digital control and signal processing module at different temperatures. When the digital control and signal processing module receives the control signal corresponding to a specific temperature adjustment point, it processes the signal through I... 2 The C bus communicates with the non-volatile memory, reading the corresponding trimming data apr<3:0> and svr<3:0> and writing them into the internal register. The digital circuit's power supply voltage is 1.8V, and the analog circuit's power supply voltage is 3.3V. The generated trimming data apr<3:0> and svr<3:0> are 1.8V voltage signals. The internal register transmits the trimming data apr<3:0> and svr<3:0> to the level shifting circuit, converting the 1.8V signal to a higher voltage. The adjustment data is converted into 3.3V adjustment data A<3:0> and S<3:0> for use by the digital adjustment resistor array. The 3.3V adjustment data A<3:0> and S<3:0> are transmitted to the decoder in the digital adjustment resistor array. A<3:0> is sent to A3, A2, A1, and A0 of the decoder, and S<3:0> is sent to A3, A2, A1, and A0 of another identical decoder. Then, the decoder outputs Y0, Y1, Y2...Y... 15 Control switches K0, K1, K2...K respectively 15 This allows for the control of the resistance values ​​in the resistor array.

4. The high-precision bandgap reference voltage source circuit based on digital adjustment according to claim 1, characterized in that... The level shifting circuit is used to realize the voltage domain conversion of temperature compensation related digital trimming codes, converting the 4-bit trimming codes apr<3:0> and svr<3:0> which operate in the 1.8 V voltage domain of digital circuits into trimming codes A<3:0> and S<3:0> which operate in the 3.3 V voltage domain of analog circuits, and sending them to the subsequent 4-to-16 decoder to control the digital trimming resistor array for temperature compensation and fine trimming of analog circuit parameters.

5. The high-precision bandgap reference voltage source circuit based on digital adjustment according to claim 1, characterized in that... The digital adjustment resistor array consists of a resistor array and a 4-16 decoder to compensate for the impact of temperature drift on circuit performance; the 4-16 decoder receives a 4-bit digital code to control the switching of the resistor array and control the magnitude of the resistors in the resistor array.

6. The high-precision bandgap reference voltage source circuit based on digital adjustment according to claim 1, characterized in that... The amplifier is a single-pole amplifier with a folded common-emitter common-base structure; this structure keeps the two branches of the common-emitter common-base amplifier symmetrical and reduces the amplifier's offset voltage.

7. The high-precision bandgap reference voltage source circuit based on digital adjustment according to claim 1, characterized in that... Frequency compensation uses zero-point compensation, which adds a series connection of resistor R6 and capacitor C2 between the amplifier and the driver, and then a compensation circuit in parallel with capacitor C1. The compensation circuit uses resistor R6 and capacitor C2 to generate a zero point to cancel the poles generated by the driver and load capacitor, and capacitor C1 reduces the bandwidth of the amplifier.

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