A high-precision reference voltage source

Abstract

The present invention discloses a high-precision reference voltage source. A control signal is generated by combining a temperature signal generated by a temperature sensor with a data table stored in a non-volatile memory. This control signal is converted into a pulse density signal via a ΣΔDA converter. The pulse density signal generates a set of non-overlapping clocks through a non-overlapping signal generation circuit to control the on and off of a pair of differential MOS transistors M1 and M2, thereby controlling the current flowing through a resistor and transistor Q1. After filtering through an RC filter circuit, a voltage signal with a very low temperature coefficient is generated. The bias current for the two MOS transistors M1 and M2 is provided by a PTAT current, which can accommodate a wide temperature range and achieve a high-precision reference voltage output.

Description

Technical Field

[0001] The present invention relates to the technical field of high-precision voltage sources, and in particular to a high-precision reference voltage source. Background Art

[0002] High-precision voltage references are key circuits within many high-precision analog and mixed-signal chips, and their performance is crucial to the overall performance of the chip. Existing designs for these circuits rely on specialized processes and equipment, such as laser trimming, to calibrate these chips before shipment, resulting in high costs. Furthermore, existing references require nonlinear compensation and high-order compensation, making it difficult to achieve the desired balance of wide temperature range, low power consumption, high precision, and high power supply voltage rejection ratio (PSR) from a system architecture perspective.

[0003] Therefore, the existing technology still needs to be improved and enhanced. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide a high-precision reference voltage source, aiming to solve the problem in the prior art that the voltage source is difficult to take into account both a wide temperature range and low power consumption.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A high-precision reference voltage source, comprising:

[0007] A digital conversion circuit, wherein the digital conversion circuit is provided with a plurality of input terminals;

[0008] A digital output temperature sensor connected to one of the input terminals of the digital conversion circuit;

[0009] a nonvolatile memory connected to one of the input terminals of the digital conversion circuit;

[0010] a ΣΔDA converter connected to the output end of the digital conversion circuit and outputting a pulse density signal to the non-overlapping signal generating circuit;

[0011] Resistor R1, one end of which is connected to MOS transistors M1 and M2, and is connected to the two-phase output ends of the non-overlapping signal generation circuit through MOS transistors M1 and M2, and the other end of resistor R1 is grounded;

[0012] RC filter circuit, connected in parallel with resistor R1;

[0013] The PTAT voltage source is connected to the MOS transistor M1 and the MOS transistor M2.

[0014] Furthermore, the RC filter circuit includes a capacitor C1, a capacitor C2 and a resistor R2, and the capacitor C1 and the capacitor C2 are connected in parallel to the resistor R2.

[0015] Furthermore, the digital conversion circuit is provided with a CPU interface C, and adjustment data can be written through the CPU.

[0016] Furthermore, one end of the resistor R1 is connected to the MOS transistors M1 and M2 and is connected to the two-phase output ends of the non-overlapping signal generating circuit through the MOS transistors M1 and M2, and the other end of the resistor R1 is connected to the transistor Q1.

[0017] The technical solution adopted by the present invention has the following beneficial effects:

[0018] In this application, a control signal is derived from the temperature signal generated by a temperature sensor and a data table stored in non-volatile memory. This control signal is converted into a pulse density signal via a ΣΔDA converter. This pulse density signal, through a non-overlapping signal generation circuit, generates a set of non-overlapping clocks to control the on and off of a pair of differential MOS transistors M1 and M2, thereby controlling the current flowing through the resistor and transistor Q1. After filtering by an RC filter circuit, a voltage signal with a very low temperature coefficient is generated. The bias current for the two MOS transistors M1 and M2 is provided by a PTAT current, which can accommodate a wide temperature range and reduce power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the circuit structure of a high-precision reference voltage source provided by the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] In an embodiment of the present invention, a high-precision reference voltage source includes a digital output temperature sensor that can output an n-bit digital code based on temperature and input it into a digital conversion circuit; a non-volatile memory, including EEPROM, FLASH, and PROM based on fuses or antifuses; a digital conversion circuit that can implement functions such as calling a netlist within the non-volatile memory, writing trim data via a CPU, and outputting a control signal X; a ΣΔDA converter that converts the control signal into a pulse density signal linearly proportional to its duty cycle; a PTAT voltage source that generates a current proportional to the absolute temperature for use in a bias circuit; a non-overlapping signal generation circuit that generates a two-phase non-overlapping clock to control the turning on and off of MOS transistors M1 and M2; and an RC filter circuit that filters out interference signals and irrelevant noise signals generated by the clock turning on and off the MOS transistors.

[0022] During use, a control signal is generated by combining the temperature signal generated by the temperature sensor with a data table stored in non-volatile memory. This control signal is converted into a pulse density signal via a Sigma-Delta ADC. This pulse density signal is then used by a non-overlapping clock generation circuit to generate a set of non-overlapping clocks to control the on and off of a pair of differential MOS transistors M1 and M2, thereby controlling the current flowing through the resistor and transistor. After filtering by an RC filter circuit, a voltage signal with a very low temperature coefficient is generated. The bias current for the two MOS transistors is provided by the PTAT current.

[0023] Specifically, before the chip leaves the factory, it can be trimmed through the CPU interface to ensure that VREF consistently meets the required accuracy within the desired temperature range. The trimmed data is then written to non-volatile memory. Subsequently, when the chip is powered on, the data is first read from the non-volatile memory to ensure that the relationship between signals X and T meets the trimmed relationship, thus accurately generating the reference voltage VREF.

[0024] In this embodiment, an on-chip temperature sensor is used in the current source circuit, which can output an n-bit digital signal T proportional to the chip temperature in real time.

[0025] The m-bit control signal X can be obtained using the temperature signal T and the data table stored in the non-volatile memory. Figure 1 The non-volatile memory in the chip can be inside or outside the chip. The memory types include EEPROM, FLASH and PROM based on fuse or antifuse.

[0026] The control signal X is converted into a pulse density signal Z by the ΣΔDA circuit. The average duty cycle of the pulse density signal Z is linearly related to X.

[0027] The pulse density signal Z is converted into Q and QN by a two-phase non-overlapping circuit, which control the P-type MOS tubes M1 and M2 respectively. The logical values ​​of Q and QN are opposite when they are stable, but they will not be in a high level state at the same time during the conversion stage.

[0028] The PTAT current source in the figure is a commonly used circuit in integrated circuits. Its output current is independent of the power supply voltage, is proportional to the absolute temperature, and is inversely proportional to the resistance of a resistor. The resistor type should be the same as R1.

[0029] The density wave Z controls the current flowing to the resistor R1 and the transistor Q1, and generates the output voltage VREF after filtering.

[0030] Before the chip leaves the factory, it can be trimmed through the CPU interface to ensure that VREF consistently meets the required accuracy within the desired temperature range. The trimmed data is then written to non-volatile memory. Subsequently, when the chip is powered on, the data is first read from the non-volatile memory to ensure that the relationship between signals X and T meets the trimmed relationship, thus accurately generating the reference voltage VREF.

[0031] It should be understood that in the embodiment of the present invention, Figure 1 In the circuit shown, the output voltage can also be generated by removing the transistor Q1 and grounding the lower end of the resistor R1. Secondly, the PTAT current source can be replaced with other temperature characteristic current sources to take into account the wide temperature characteristics of the voltage source.

[0032] The technical solution adopted by the present invention has the following beneficial effects:

[0033] (1) In the voltage source design, a digital output temperature sensor is used to measure the chip temperature in real time;

[0034] (2) In the voltage source design, a digital output temperature sensor, a non-volatile memory, a digital conversion circuit, a ΣΔDA converter, a PTAT current source, a non-overlapping signal generation circuit and an RC filter circuit are used to Figure 1 The connection shown generates an output voltage VREF across resistor R1 and transistor Q1.

[0035] Other embodiments of the present invention will readily occur to those skilled in the art after considering the specification and practicing the embodiments disclosed herein. The present invention is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the claims.

Claims

1. A high-precision reference voltage source, characterized in that: include: A digital conversion circuit, wherein the digital conversion circuit is provided with a plurality of input terminals; A digital output temperature sensor connected to one of the input terminals of the digital conversion circuit; a nonvolatile memory connected to one of the input terminals of the digital conversion circuit; a ΣΔDA converter connected to the output end of the digital conversion circuit and outputting a pulse density signal to the non-overlapping signal generating circuit; A resistor R1, one end of which is connected to a MOS transistor M2, a source end of which is connected to a MOS transistor M1, and a drain end of which is connected to the MOS transistor M2. The gates of the MOS transistors M1 and M2 are respectively connected to the two-phase output ends of the non-overlapping signal generation circuit, and the other end of the resistor R1 is grounded. an RC filter circuit, one end of which is connected to the one end of the resistor R1 and the other end of which is grounded; The PTAT voltage source is connected to the MOS transistor M1 and the MOS transistor M2.

2. The high-precision reference voltage source according to claim 1, wherein: The RC filter circuit includes capacitor C1, capacitor C2 and resistor R2; one end of capacitor C1 is connected to one end of resistor R2 and the one end of resistor R1, and the other end is grounded; the other end of resistor R2 is connected to one end of capacitor C2, and the other end of capacitor C2 is grounded.

3. The high-precision reference voltage source according to claim 1, wherein: The digital conversion circuit is provided with a CPU interface C, and adjustment data can be written into the CPU.

4. The high-precision reference voltage source according to claim 1, wherein: One end of the resistor R1 is connected to the MOS transistor M2, the source end of the MOS transistor M2 is connected to the MOS transistor M1, the resistor R1 is connected to the drain end of the MOS transistor M2, the gates of the MOS transistors M1 and M2 are respectively connected to the two-phase output ends of the non-overlapping signal generation circuit, and the other end of the resistor R1 is connected to the transistor Q1.

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