Delta-Sigma converter
By combining adjustable resistors with operational amplifiers, capacitors, and quantizers, the signal-to-noise ratio and overload issues in gain adjustment of Delta-Sigma converters are solved, achieving flexible gain adjustment and improved anti-interference capability.
Patent Information
- Application Number
- CN202480038304.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-06-07
- Filing Date
- 2024-05-22
- Publication Date
- 2026-02-03
AI Technical Summary
Existing Delta-Sigma converters struggle to simultaneously optimize signal-to-noise ratio and avoid overload when adjusting signal gain, and require additional amplification stages for gain adjustment.
It employs a combination of adjustable resistors, operational amplifiers, capacitors, a 1-bit quantizer, and a 1-bit D/A converter. The gain can be flexibly adjusted through the adjustable resistors, avoiding impact on the input impedance and noise transfer function, and eliminating the need for additional amplification stages.
It enables flexible gain adjustment, simplifies the signal adjustment process, improves the signal-to-noise ratio, avoids overload, and enhances anti-interference capability.
Smart Images
Figure CN121464580A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a Delta-Sigma converter. Background Technology
[0002] So-called "continuous-time" Delta-Sigma converters are known in the prior art, for example, for converting analog signals from sensors into digital signals. For this purpose, Delta-Sigma converters can be directly integrated into such sensors to enable the subsequent transmission of the digitally converted sensor signals with particularly high interference immunity.
[0003] In this case, it is usually necessary to adjust the gain of the signal to be converted by the Delta-Sigma converter in order to obtain the best signal-to-noise ratio and / or avoid overload of the Delta-Sigma converter.
[0004] The paper "Design of High-Resolution Continuous-Time Delta–Sigma Data Converters With Dual Return-to-Open DACs" by R. Theertham, SNGanta, and S. Pavan (published in IEEE Solid State Circuits Journal, 2022, doi: 10.1109 / JSSC.2022.3176876) describes an RC-based integrator for a Delta-Sigma converter, where the input coefficients of the Delta-Sigma converter are adjusted via input resistors.
[0005] The paper "A CMOS 110-dB@40-kS / s programmable-gain chopper-stabilized third-order 2-1 cascade sigma-delta Modulator for low-power high-linearity automotive sensor ASICs" by JMdelaRosa et al. (published in IEEE Solid State Circuits Journal, Vol. 40, No. 11, pp. 2246-2264, November 2005, doi: 10.1109 / JSSC.2005.857356) describes an RC integrator for a Delta-Sigma converter, in which the input gain is adjusted by the feedback coefficients of the Delta-Sigma converter.
[0006] The paper "A Continuous-Time Delta-Sigma Modulator Using a Modified Instrumentation Amplifier and Current Reuse DAC for Neural Recording" by A. Nikas, S. Jambunathan, L. Klein, M. Voelker, and M. Ortmanns (published in IEEE Solid State Circuits Journal, Vol. 54, No. 10, pp. 2879-2891, October 2019, doi: 10.1109 / JSSC.2019.2931811) describes the use of a modified instrumentation amplifier as an integrator in a Delta-Sigma modulator. Summary of the Invention
[0007] According to a first aspect of the invention, a Delta-Sigma converter is proposed, which includes an operational amplifier, a capacitor, a quantizer, a D / A converter (digital-to-analog converter), and an adjustable resistor.
[0008] The capacitor (e.g., a fixed capacitor or an adjustable capacitor (also known as a "tunable" capacitor, particularly useful in tuning circuits)) is connected between the output of the operational amplifier and its inverting input, while an adjustable resistor is connected between the inverting input and a reference potential and configured to provide at least one first resistance value and a second resistance value different from the first resistance value, depending on the tuning. The reference potential is, for example, ground or a different potential (e.g., a "common-mode" potential). The adjustable resistor, capacitor, and operational amplifier together constitute the integrator of the input stage of the Delta-Sigma converter according to the invention.
[0009] The input of the quantizer is connected to the output of the operational amplifier, wherein the quantizer is configured as a 1-bit quantizer. The output of the quantizer is connected to the input of a D / A converter, wherein the D / A converter is configured as a 1-bit D / A converter. The output of the D / A converter is connected to the inverting input of the operational amplifier to receive a feedback current. For this purpose, the D / A converter provides, for example, an output voltage, from which the feedback current is generated via a feedback resistor. Alternatively or additionally, it is conceivable that the D / A converter includes a current source upon which the feedback current is generated.
[0010] Furthermore, the Delta-Sigma converter is configured to receive the signal to be digitally converted (i.e., the input signal of the Delta-Sigma converter) through the non-inverting input of the operational amplifier, and amplify the signal in accordance with the value of the adjustable resistor before digital conversion. It is important to note that amplification can be either positive or negative (i.e., attenuation).
[0011] Furthermore, it should be noted that the output signal of the Delta-Sigma converter is advantageously low-pass filtered and / or downsampled, which is preferably implemented according to the prior art; therefore, to avoid repetition on this, please refer to the prior art.
[0012] The Delta-Sigma converter according to the invention offers the following advantages: the desired gain can be flexibly adjusted via an adjustable resistor (which, according to the above configuration, is completely decoupled from the signal-generating components) without affecting the input impedance of the Delta-Sigma converter and / or the voltage swing and / or noise transfer function (NTF) of the integrator. Furthermore, the Delta-Sigma converter according to the invention requires no additional amplification stage for gain adjustment.
[0013] Furthermore, only one coefficient, namely the input gain of the Delta-Sigma converter, is affected by the change in the adjustable resistor, so the adjustment of the input signal gain can be achieved particularly easily.
[0014] The dependent claims illustrate preferred extensions of the invention.
[0015] In an advantageous configuration of the invention, the adjustable resistor is configured to be stepped or adjusted in predefined stages, wherein the predefined stages are uniform or non-uniform.
[0016] Particularly advantageously, the adjustable resistor is constructed as a resistor network comprising a plurality of individual resistors connected in parallel and / or series, wherein at least one of the individual resistors is connected to a switch configured to selectively switch the individual resistor to active or inactive based on the switch's position (Stellung) within the resistor network, thereby adjusting a first resistance value or a second resistance value according to the corresponding switch position. More preferably, most of the individual resistors, and even more preferably, each of the individual resistors, is provided with a corresponding switch to adjust a plurality of different resistance values, thereby allowing for the configuration of a correspondingly high number of different gain coefficients. For this purpose, the corresponding switches to the individual resistors are particularly constructed as switches that are independently switchable. It should be noted that these switches can be manually adjustable and / or automatically (i.e., electrically) operable switches. Alternatively or additionally, it is also conceivable that the switches are constructed as manually and / or automatically (e.g., by means of a motor) adjustable potentiometers (e.g., rotary potentiometers and / or fine-tuning potentiometers, etc.).
[0017] Particularly preferably, at least one switch (or part or all of the switches used herein) is a semiconductor switch, especially a MOSFET. Alternatively or additionally, it is also conceivable that at least one switch is constructed as an electromechanical switch (e.g., a relay).
[0018] In another advantageous configuration of the invention, the Delta-Sigma converter further includes a control unit, which may be configured as, for example, an ASIC, FPGA, processor, digital signal processor, microcontroller, etc. In this case, the adjustable resistor is an electrically adjustable resistor, for example, which may be electrically adjustable via the aforementioned switch (especially a semiconductor switch), wherein the control unit is configured to manipulate the adjustable resistor in accordance with a desired gain for the signal. The desired gain is, for example, a predefined gain and / or a gain to be dynamically adjusted.
[0019] Advantageously, the control unit is configured to adjust the signal gain based on the amplitude and / or distortion and / or signal-to-noise ratio of the converted signal. To this end, the control unit is advantageously connected to the output of the Delta-Sigma converter via information technology to receive and analyze the converted signal. Alternatively or additionally, the control unit is configured to adjust the signal gain based on information about the component generating the signal. Such information about the component generating the signal represents, for example, the type and / or configuration and / or usage scenario and / or operating mode of the component, so that appropriate and / or corresponding gains can be adjusted by the control unit based on this information.
[0020] Preferably, the Delta-Sigma converter is at least partially and particularly preferably entirely constructed as an integrated circuit and especially as a CMOS circuit.
[0021] Alternatively or additionally, the Delta-Sigma converter according to the invention is configured as at least a second-order converter or as a higher-order converter to obtain an improved signal-to-noise ratio.
[0022] Particularly advantageously, the Delta-Sigma converter according to the invention is configured for converting signals from sensors (especially vehicle sensors). Such vehicle sensors are, for example, ultrasonic and / or radar and / or lidar and / or capacitive sensors and / or camera devices, which are particularly useful as environmental detection sensors.
[0023] According to a second aspect of the invention, a symmetrical Delta-Sigma converter is proposed, comprising a first Delta-Sigma converter according to a first aspect of the invention and a second Delta-Sigma converter according to a first aspect of the invention. The corresponding adjustable resistors of the two Delta-Sigma converters are connected to each other at the same reference potential, which is implemented, for example, as so-called "common-mode feedback". This symmetrically constructed Delta-Sigma converter (which includes an integrator substantially based on a modified instrumentation amplifier) is accordingly configured to receive the signal to be converted with respect to the reference potential symmetrical construction through the non-inverting inputs of the operational amplifiers of the first Delta-Sigma converter and the second Delta-Sigma converter. Features, combinations of features, and the resulting advantages are readily apparent and correspond to what is described in conjunction with the inventive aspects mentioned earlier; to avoid repetition, please refer to the above description. Attached Figure Description
[0024] Embodiments of the present invention are described in detail below with reference to the accompanying drawings. As shown herein: Figure 1According to embodiments of the Delta-Sigma converter of the present invention, and Figure 2 An embodiment of the symmetric Delta-Sigma converter according to the present invention. Detailed Implementation
[0025] Figure 1 An embodiment of the Delta-Sigma converter according to the present invention is shown, which includes an operational amplifier 10, a capacitor 20, a quantizer 30, a D / A converter 40, and an adjustable resistor 50.
[0026] Quantizer 30 is constructed as a 1-bit quantizer, and D / A converter 40 is constructed as a 1-bit D / A converter.
[0027] Capacitor 20 is connected between the output terminal 16 of operational amplifier 10 and the inverting input terminal 14 of operational amplifier 10.
[0028] An adjustable resistor 50 is connected between the inverting input 14 of the operational amplifier 10 and ground potential 60. The adjustable resistor 50 is constructed from a plurality of individual resistors 50, each having the same resistance value, and the plurality of individual resistors together form a resistor network. Furthermore, the adjustable resistor 50 includes a control unit 90 configured as a logic circuit, which is connected via information technology to a first switch 80 and a second switch 82, wherein the two switches 80 and 82 are respectively configured as MOSFETs. The control unit 90 is thus configured to independently operate the two switches 80 and 82 to adjust their respective desired switching states.
[0029] In this way, the control unit 90 is configured to adjust the adjustable resistor 50 to different resistance values according to the corresponding switching states of switches 80 and 82. The logic circuit determines the respective required resistance values for the adjustable resistor 50 based on information about the current operating mode of a component (not shown). This component generates a signal S to be converted using a Delta-Sigma converter, which is fed through the non-inverting input 12 of the operational amplifier 10 to adjust the gain of the signal S, which is affected by the adjustable resistor 50, to a level predetermined by the adjustable resistor 50. The signal S here is asymmetrically constructed relative to the ground potential 60.
[0030] It should be noted that the resistance values of individual resistors 50 can be at least partially different from each other to enable a non-uniform amplification stage. Furthermore, it should be noted that the number of individual resistors 50 and the number of switches 80, 82 used is, in principle, unlimited.
[0031] In addition, it should be noted that the adjustable resistor 50 can be, for example, a potentiometer that can be automatically controlled by a motor.
[0032] Furthermore, the input terminal 32 of the quantizer 30 is connected to the output terminal 16 of the operational amplifier 10, while the output terminal 34 of the quantizer 30 is connected to the input terminal 42 of the D / A converter 40. The output terminal 44 of the D / A converter 40 is connected to the inverting input terminal 14 of the operational amplifier 10 through the feedback resistor 100 to inject a corresponding feedback current.
[0033] The digital filter 70 connected to the output terminal 34 of the quantizer 30 is configured to perform low-pass filtering and downsampling on the quantized signal S, and output the processed signal S as the digitized signal S' for subsequent processing.
[0034] Figure 2 An embodiment of a symmetric Delta-Sigma converter according to the present invention is shown, which consists of a first Delta-Sigma converter according to the present invention and a second Delta-Sigma converter according to the present invention.
[0035] A symmetrical Delta-Sigma converter is used to digitize the (measured) signal S generated by the (not shown) ultrasonic sensor of the vehicle, so that the signal S can then be transmitted digitally to the (not shown) ultrasonic control unit with particularly high interference immunity via the vehicle's onboard network.
[0036] because Figure 2 Symmetric Delta-Sigma converters in Figure 1 There are many similarities between the Delta-Sigma converters in the two languages. To avoid repetition, only the differences between them will be explained below. For the rest, please refer to [link to relevant documentation]. Figure 1 .
[0037] The respective adjustable resistors 50 of the two Delta-Sigma converters are connected to each other at a common reference potential 60 (or also referred to as the “reference potential”), which is here the “common mode” potential.
[0038] The symmetrical Delta-Sigma converter is configured to receive the signal S to be converted, symmetrically constructed with respect to a reference potential 60, through the non-inverting input 12 of the operational amplifier 10 of the first Delta-Sigma converter and the non-inverting input 12 of the operational amplifier 10 of the second Delta-Sigma converter. In other words, the portion of the signal S that is positive with respect to the reference potential is fed into the first Delta-Sigma converter (e.g., ...). Figure 2As shown in the upper part), the signal portion of signal S that is negative with respect to the reference potential is fed into the second Delta-Sigma converter (as shown in the upper part). Figure 2 (As shown in the lower part).
[0039] The quantizer 30 is configured here as a common quantizer 30 for both Delta-Sigma converters, while the corresponding D / A converter 40 is configured here as a separate component. It should be noted that the D / A converter 40 can instead be a shared D / A converter 40.
[0040] In addition, it should be noted that, for clarity, the corresponding information technology connections between control unit 90 and switches 80, 82, 84, and 86 are not shown here, but these connections are set up to individually control the respective switches 80, 82, 84, and 86.
[0041] The control unit 90 is configured to receive the digitized signal S' and to operate switches 80, 82, 84, and 86 according to the maximum level of the digitized signal S' to achieve the optimal gain of the signal S, which avoids overload of the signal S and optimizes the signal-to-noise ratio in the digitized signal S'.
[0042] Furthermore, capacitor 20 is configured here as a finely adjustable capacitor 20 to simplify the tuning of the symmetrical Delta-Sigma converter.
Claims
1. A Delta-Sigma converter, comprising: Operational amplifier (10) Capacitor (20) Quantizer (30) D / A converter (40), and Adjustable resistor (50). in, The capacitor (20) is connected between the output terminal (16) of the operational amplifier and the inverting input terminal (14) of the operational amplifier (10). The adjustable resistor (50) is connected between the inverting input terminal (14) of the operational amplifier (10) and the reference potential (60) and is configured to provide at least one first resistance value and a second resistance value different from the first resistance value according to the setting. The input terminal (32) of the quantizer (30) is connected to the output terminal (16) of the operational amplifier (10), wherein the quantizer (30) is configured as a 1-bit quantizer. The output terminal (34) of the quantizer (30) is connected to the input terminal (42) of the D / A converter (40), wherein the D / A converter (40) is configured as a 1-bit D / A converter. The output terminal (44) of the D / A converter (40) is connected to the inverting input terminal (14) of the operational amplifier (10) to feed in feedback current, and The Delta-Sigma converter is configured to, The signal (S) to be digitally converted is received through the non-inverting input (12) of the operational amplifier (10). Before digital conversion, the signal (S) is amplified in accordance with the value of the adjustable resistor (50).
2. The Delta-Sigma converter according to claim 1, wherein, The adjustable resistor (50) is configured to be stepless or adjusted in predefined stages, wherein the predefined stages are uniform or non-uniformly constructed stages.
3. The Delta-Sigma converter according to any one of the preceding claims, wherein, The adjustable resistor (50) The resistor network is constructed as a resistor network comprising a plurality of individual resistors (50) connected in parallel and / or series, wherein at least one of the individual resistors (50) is connected to a switch (80) configured to selectively switch the individual resistor (50) to active or inactive based on the positional state of the switch (80) within the resistor network, and / or It is constructed as a potentiometer that can be manually and / or automatically adjusted.
4. The Delta-Sigma converter according to claim 3, wherein, At least one switch (80) is Semiconductor switches, especially MOSFETs, and / or Electromechanical switches.
5. The Delta-Sigma converter according to any one of the preceding claims further includes a control unit (90), wherein, The adjustable resistor (50) is an electrically adjustable resistor (50). The control unit (90) is configured to manipulate the adjustable resistor (50) in accordance with the desired gain for the signal (S).
6. The Delta-Sigma converter according to claim 5, wherein, The control unit (90) is configured to, according to The amplitude and / or Distortion of the converted signal (S'), and / or The signal-to-noise ratio of the converted signal (S'), and / or Information about the components that generate the signal (S) Adjust the gain of the signal (S).
7. The Delta-Sigma converter according to any one of the preceding claims, wherein, The Delta-Sigma converter is at least partially constructed as an integrated circuit and, in particular, as a CMOS circuit.
8. The Delta-Sigma converter according to any one of the preceding claims, wherein, The Delta-Sigma converter is at least constructed as a second-order converter.
9. The Delta-Sigma converter according to any one of the preceding claims, wherein, The Delta-Sigma converter is configured to convert signals (S) from sensors, particularly vehicle sensors.
10. A symmetric Delta-Sigma converter, comprising The first Delta-Sigma converter according to any one of the preceding claims, and The second Delta-Sigma converter according to any one of the preceding claims, in, The corresponding adjustable resistors (50) of the two Delta-Sigma converters are connected to each other at the same reference potential (60). The symmetrical Delta-Sigma converter is configured to receive a signal (S) to be converted symmetrically constructed with respect to the reference potential (60) through the non-inverting input (12) of the operational amplifier (10) of the first Delta-Sigma converter and the non-inverting input (12) of the operational amplifier (10) of the second Delta-Sigma converter.