Continuous-time bandpass sigma-delta modulator and electronic device

Abstract

The application provides a continuous-time band-pass Sigma-Delta modulator and electronic equipment, the continuous-time band-pass Sigma-Delta modulator comprising a transconductance operational amplifier, a passive resonator, a sampling quantizer, a current feedback module and a voltage feedback module.In the application, the continuous-time band-pass Sigma-Delta modulator is designed in combination with the transconductance operational amplifier, the passive resonator, the sampling quantizer, the current feedback module and the voltage feedback module, the voltage feedback is added on the basis of the conventional current feedback, the current feedback and the voltage feedback can be simultaneously realized, the feedback freedom degree is increased, so that the whole modulator can realize arbitrary band-pass Sigma-Delta modulator noise transfer function, which effectively solves the limitation of the system performance of the continuous-time band-pass Sigma-Delta modulator based on the inductance-capacitance resonator due to the lack of feedback freedom degree, and improves the performance of the modulator.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, and in particular to a continuous-time bandpass Sigma-Delta modulator and electronic device. Background Technology

[0002] Continuous-time Sigma-Delta modulators (CTDMs) are characterized by low power consumption, high speed, and inherent anti-aliasing properties, significantly reducing the design requirements for front-end anti-aliasing filters and effectively minimizing chip area. These features have led to the widespread use of CTDMs. Bandpass CTDMs, in particular, possess these characteristics and can directly digitize intermediate frequency (IF) signals, greatly simplifying the complexity of receiver systems. The loop filter in a bandpass CTDM typically consists of a resonator composed of an active RC integrator or an inductor-capacitor resonator. Since inductor-capacitor resonators are passive devices, and ideally only energy storage devices, they consume no power. Furthermore, inductor-capacitor resonators can achieve a higher quality factor and provide earlier gain, resulting in superior noise performance compared to resonators composed of active RC integrators.

[0003] However, existing continuous-time bandpass Sigma-Delta modulator techniques based on inductor-capacitor resonators suffer from a lack of feedback freedom. For a second-order inductor-capacitor resonator, the modulator output feedback consists of only a current signal. This deficiency prevents the implementation of arbitrary noise transfer functions for bandpass Sigma-Delta modulators. Consequently, the selection of loop parameters in the design of continuous-time bandpass Sigma-Delta modulators based on inductor-capacitor resonators is limited, directly impacting the overall modulator performance.

[0004] Therefore, there is an urgent need for a technical solution that can realize arbitrary noise transfer functions for bandpass Sigma-Delta modulators based on more feedback degrees of freedom. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a continuous-time bandpass Sigma-Delta modulator based on an inductor-capacitor resonator, which adds a voltage feedback to the current feedback to compensate for the missing degree of freedom and solve the limitation of the missing degree of freedom on the performance of the continuous-time bandpass Sigma-Delta modulator system based on the inductor-capacitor resonator.

[0006] To achieve the above and other related objectives, the technical solution provided by this invention is as follows.

[0007] A continuous-time bandpass Sigma-Delta modulator, comprising:

[0008] A transconductance operational amplifier is used to receive an input voltage signal and convert the input voltage signal to obtain and output a current signal.

[0009] A passive resonator, acting as a loop filter, is connected to the output of the transconductance operational amplifier to convert the current signal and obtain and output an intermediate voltage signal.

[0010] A sampling quantizer, connected to the output of the passive resonator, samples and quantizes the intermediate voltage signal to obtain and output the thermometer code.

[0011] The current feedback module has its input terminal connected to the output terminal of the sampling quantizer and its output terminal connected to the passive resonator, and provides feedback current to the passive resonator under the control of the thermometer code;

[0012] The voltage feedback module has its input terminal connected to the output terminal of the sampling quantizer and its output terminal connected to the passive resonator, and provides feedback voltage to the passive resonator under the control of the thermometer code.

[0013] Optionally, the passive resonator includes a capacitor and an inductor. One end of the capacitor is connected to the output terminal of the transconductance operational amplifier, and the other end of the capacitor is grounded. One end of the inductor is connected to the output terminal of the transconductance operational amplifier, and the other end of the inductor is connected to the output terminal of the sampling quantizer via the voltage feedback module connected in series. The end of the inductor connected to the output terminal of the transconductance operational amplifier outputs the intermediate voltage signal.

[0014] Optionally, the thermometer code includes a four-digit thermometer code, and the current feedback module includes a first current source, a second current source, a third current source, a fourth current source, a fifth current source, a first switch, a second switch, a third switch, and a fourth switch. The operating voltage is grounded after passing through the first current source, the first switch, and the second current source connected in series. The operating voltage is also grounded after passing through the first current source, the second switch, and the third current source connected in series. The operating voltage is also grounded after passing through the first current source, the third switch, and the fourth current source connected in series. The control terminal of the first switch is connected to the first digit of the four-digit thermometer code, the control terminal of the second switch is connected to the second digit of the four-digit thermometer code, the control terminal of the third switch is connected to the third digit of the four-digit thermometer code, and the control terminal of the fourth switch is connected to the fourth digit of the four-digit thermometer code. The common terminal of the first switch, the second switch, the third switch, and the fourth switch outputs the feedback current, which is connected to the output terminal of the transconductance operational amplifier.

[0015] Optionally, the voltage feedback module includes an output voltage adjustment unit, a voltage divider unit, and a selection output unit. The output voltage adjustment unit outputs an adjustable initial voltage. The input terminal of the voltage divider unit is connected to the output terminal of the output voltage adjustment unit. The voltage divider unit performs voltage division processing on ground, the operating voltage, and the initial voltage to obtain and output multiple initial feedback voltages of different magnitudes. The multiple input terminals of the selection output unit are connected one-to-one with the multiple initial feedback voltages. The control terminal of the selection output unit is connected to the thermometer code. Under the control of the thermometer code, the selection output unit selects one of the multiple initial feedback voltages as the feedback voltage and outputs it. The output terminal of the selection output unit is connected to the end of the inductor furthest from the transconductance operational amplifier.

[0016] Optionally, the output voltage regulation unit includes N reference current sources, N digitally controlled switches, a first resistor, a first operational amplifier, and an NMOS transistor. The N reference current sources and the N digitally controlled switches form N parallel current branches. Each current branch includes one reference current source and one digitally controlled switch connected in series. The end of each reference current source furthest from the digitally controlled switch is connected to the operating voltage. The control terminals of the N digitally controlled switches are connected one-to-one with the N bits of the N-bit digital code. The ends of the N digitally controlled switches furthest from the reference current sources are short-circuited and connected to one end of the first resistor. The other end of the first resistor is grounded. The non-inverting input terminal of the first operational amplifier is connected to the common terminal of the N digitally controlled switches. The inverting input terminal of the first operational amplifier is connected to the source of the NMOS transistor. The output terminal of the first operational amplifier is connected to the gate of the NMOS transistor. The source of the NMOS transistor outputs the initial voltage. Here, N is an integer greater than or equal to 2.

[0017] Optionally, the voltage divider unit includes a second resistor and four third resistors. The operating voltage is connected to the drain of the NMOS transistor via the first, second, third, and fourth third resistors connected in series. The source of the NMOS transistor is grounded via the second resistor connected in series. An initial feedback voltage is output from the end of the first third resistor closest to the operating voltage. An initial feedback voltage is output from the common terminal of the first and second third resistors. An initial feedback voltage is output from the common terminal of the second and third third resistors. An initial feedback voltage is output from the common terminal of the third and fourth third resistors. An initial feedback voltage is output from the end of the fourth third resistor closest to the NMOS transistor.

[0018] Optionally, the selection output unit includes a data selector and a second operational amplifier. The five input terminals of the data selector are connected one-to-one with the five initial feedback voltages. The control terminal of the data selector is connected to the thermometer code. The output terminal of the data selector is connected to the non-inverting input terminal of the second operational amplifier. The inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier. The output terminal of the second operational amplifier outputs the feedback voltage.

[0019] Optionally, the voltage feedback module further includes an output common-mode regulation unit, the output of which is connected to the voltage divider unit, and the output common-mode regulation unit stabilizes and clamps the common-mode value of the feedback voltage.

[0020] Optionally, the output common-mode adjustment unit includes a third operational amplifier and a PMOS transistor. The source of the PMOS transistor is connected to the operating voltage, the gate of the PMOS transistor is connected to the output terminal of the third operational amplifier, the inverting input terminal of the third operational amplifier is connected to a reference voltage, the non-inverting input terminal of the third operational amplifier is connected to the common terminal of the second and third third resistors, and the drain of the PMOS transistor is connected to the end of the first third resistor away from the second third resistor.

[0021] An electronic device comprising a continuous-time bandpass Sigma-Delta modulator as described in any of the preceding claims.

[0022] As described above, the continuous-time bandpass Sigma-Delta modulator and electronic device of the present invention have at least the following beneficial effects:

[0023] A continuous-time bandpass Sigma-Delta modulator was designed by combining a transconductance operational amplifier, a passive resonator, a sampling quantizer, a current feedback module, and a voltage feedback module. Voltage feedback was added to the conventional current feedback, enabling simultaneous current and voltage feedback and increasing the feedback degree of freedom. This allows the entire modulator to achieve any noise transfer function of the bandpass Sigma-Delta modulator, effectively solving the performance limitations of continuous-time bandpass Sigma-Delta modulator systems based on inductor-capacitor resonators caused by the lack of feedback degree of freedom, thus improving the modulator's performance. Attached Figure Description

[0024] Figure 1 The diagram shown is a structural block diagram of the continuous-time bandpass Sigma-Delta modulator in this invention.

[0025] Figure 2 Displayed as Figure 1 Circuit structure diagram of medium current feedback module 4.

[0026] Figure 3 Displayed as Figure 1 Circuit structure diagram of medium voltage feedback module 5.

[0027] Figure 4 The diagram shows the block diagram of a continuous-time bandpass Sigma-Delta modulator with a CRFB structure. Detailed Implementation

[0028] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0029] Please see Figures 1 to 4 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show components relevant to the present invention and are not drawn according to the actual number, shape, and size of the components in implementation. In actual implementation, the form, quantity, and proportion of each component can be arbitrarily changed, and the component layout may be more complex. The structures, proportions, sizes, etc., depicted in the accompanying drawings are only for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effects and objectives of the present invention, should still fall within the scope of the technical content disclosed in the present invention.

[0030] As described in the background section, the inventors discovered that in existing continuous-time bandpass Sigma-Delta modulator techniques based on inductor-capacitor resonators, for a second-order inductor-capacitor resonator, the modulator output feedback consists of only a current signal based on a current feedback module. This limited feedback freedom prevents the current technology from achieving arbitrary noise transfer functions for the bandpass Sigma-Delta modulator, thus restricting the selection of loop parameters in the design of continuous-time bandpass Sigma-Delta modulators based on inductor-capacitor resonators, directly impacting the overall modulator performance.

[0031] Based on this, such as Figure 1 As shown, this invention proposes a continuous-time bandpass Sigma-Delta modulator, which includes:

[0032] Transconductance operational amplifier 1 is connected to the input voltage signal u and converts the input voltage signal u to obtain and output the current signal I0;

[0033] Passive resonator 2, as a loop filter, is connected to the output of transconductance operational amplifier 1 to convert the current signal I0 and obtain and output the intermediate voltage signal x1.

[0034] The sampling quantizer 3 is connected to the output of the passive resonator 2. It samples and quantizes the intermediate voltage signal x1 to obtain and output the thermometer code DN.

[0035] The current feedback module 4 has its input connected to the output of the sampling quantizer 3 and its output connected to the passive resonator 2. Under the control of the thermometer code DN, it provides a feedback current I to the passive resonator 2. OUT ;

[0036] Voltage feedback module 5 has its input terminal connected to the output terminal of sampling quantizer 3, and its output terminal connected to passive resonator 2. Under the control of thermometer code DN, it provides feedback voltage V to passive resonator 2. OUT .

[0037] Among them, transconductance operational amplifier 1 can adopt a conventional transconductance operational amplifier structure, with a corresponding transconductance of g. m It converts the input voltage signal u to obtain and outputs the current signal I0, where I0 = g m u.

[0038] In detail, such as Figure 1 As shown, the passive resonator 2 is an inductor-capacitor type resonator, which includes a capacitor C and an inductor L. One end of the capacitor C is connected to the output terminal of the transconductance operational amplifier 1, and the other end of the capacitor C is grounded. One end of the inductor L is connected to the output terminal of the transconductance operational amplifier 1, and the other end of the inductor L is connected to the output terminal of the sampling quantizer 3 after passing through the series-connected voltage feedback module 5. The end of the inductor L connected to the output terminal of the transconductance operational amplifier 1 outputs an intermediate voltage signal x1, which is the voltage on the capacitor C.

[0039] In detail, in an optional embodiment of the invention, such as Figures 1-2 As shown, the sampling quantizer 3 can be a 5-level parallel comparator analog-to-digital converter, which samples and quantizes the intermediate voltage signal x1 on the passive resonator 2 at a sampling frequency fs, and obtains a 4-bit thermometer code DN by analog-to-digital conversion, i.e. Figure 2 IN as shown <0> IN <1> IN <2> and IN <3> The corresponding digital voltage is denoted as V. It is understood that the sampling quantizer 3 can also be an analog-to-digital converter with other structures and other bit widths; this is not limited here.

[0040] In detail, in an optional embodiment of the invention, such as Figure 2As shown, the current feedback module 4 includes a first current source I1, a second current source I2, a third current source I3, a fourth current source I4, a fifth current source I5, a first switch K1, a second switch K2, a third switch K3, and a fourth switch K4. The operating voltage VDD is grounded after passing through the first current source I1, the first switch K1, and the second current source I2 connected in series. The operating voltage VDD is also grounded after passing through the first current source I1, the second switch K2, and the third current source I3 connected in series. The operating voltage VDD is also grounded after passing through the first current source I1, the third switch K3, and the fourth current source I4 connected in series. The operating voltage VDD is also grounded after passing through the first current source I1, the fourth switch K4, and the fifth current source I5 connected in series. The control terminal of the first switch K1 is connected to the first bit IN of the four-digit thermometer code DN. <0> The control terminal of the second switch K2 is connected to the second digit IN of the four-digit thermometer code DN. <1> The control terminal of the third switch K3 is connected to the third bit IN of the four-digit thermometer code DN. <2> The control terminal of the fourth switch K4 is connected to the fourth bit IN of the four-digit thermometer code DN. <3> The common terminal of the first switch K1, the second switch K2, the third switch K3, and the fourth switch K4 outputs a feedback current I. OUT Feedback current I OUT Connect to the output terminal of the transconductance operational amplifier 1.

[0041] Among them, the output current of the first current source I1 is I1, and the output currents of the second current source I2, the third current source I3, the fourth current source I4, and the fifth current source I5 are equal and denoted as I2, and I1 = 2I2. This is achieved through IN. <0> IN <1> IN <2> and IN <3> The gating control allows for adjustment of the output feedback current I. OUT The magnitude of the current source I1, the second current source I2, the third current source I3, the fourth current source I4, and the fifth current source I5 can be arbitrarily set, and is not limited to this.

[0042] In detail, in an optional embodiment of the invention, such as Figure 3 As shown, the voltage feedback module 5 includes an output voltage adjustment unit 51, a voltage divider unit 52, and an output selection unit 53. The output voltage adjustment unit 51 outputs an adjustable initial voltage V0. The input terminal of the voltage divider unit 52 is connected to the output terminal of the output voltage adjustment unit 51. The voltage divider unit 52 performs voltage division processing on ground, working voltage VDD, and initial voltage V0 to obtain and output multiple initial feedback voltages of different magnitudes, such as VF1 to VF5. Multiple input terminals of the output selection unit 53 are connected one-to-one with multiple initial feedback voltages. The control terminal of the output selection unit 53 is connected to a thermometer code DN. Under the control of the thermometer code DN, the output selection unit 53 selects one of the multiple initial feedback voltages as the feedback voltage V. OUT And output, select the output terminal of the output unit 53 to be connected to the end of the inductor L that is away from the transconductance operational amplifier 1.

[0043] More in detail, such as Figure 3 As shown, the output voltage regulation unit 51 includes N reference current sources I0, N digitally controlled switches K0, a first resistor R1, a first operational amplifier A1, and an NMOS transistor M1. The N reference current sources I0 and the N digitally controlled switches K0 form N parallel current branches. Each current branch includes a reference current source I0 and a digitally controlled switch K0 connected in series. The end of each reference current source I0 furthest from the digitally controlled switch K0 is connected to the operating voltage VDD. The control terminals of the N digitally controlled switches K0 are connected one-to-one with the N bits of the N-bit digital code, as shown in the figure. The 8-bit digital code shown in I_ADJ<0:7> is used. The ends of N digitally controlled switches K0 that are furthest from the reference current source I0 are shorted and connected to one end of the first resistor R1. The other end of the first resistor R1 is grounded. The non-inverting input of the first operational amplifier A1 is connected to the common terminal of the N digitally controlled switches K0. The inverting input of the first operational amplifier A1 is connected to the source of the NMOS transistor M1. The output of the first operational amplifier A1 is connected to the gate of the NMOS transistor M1. The source of the NMOS transistor M1 outputs the initial voltage V0. Here, N is an integer greater than or equal to 2.

[0044] The digital code used for controlling the on / off state of the CNC switch K0 is an 8-bit I_ADJ<0:7>, corresponding to 8 current branches, with N taking the value of 8. It should be noted that the digital code used for controlling the on / off state of the CNC switch K0 is not limited to... Figure 1 The 8-bit I_ADJ<0:7> shown can also be any other number of bits, depending on the value of N, which is not limited here.

[0045] More in detail, such as Figure 3 As shown, the on / off state of N current branches in the output voltage regulation unit 51 is controlled by an N-bit digital code to regulate the current flowing through the first resistor R1, thereby regulating the voltage at the non-inverting input of the first operational amplifier A1. The first operational amplifier A1, in conjunction with the NMOS transistor M1, follows the output voltage at the non-inverting input of the first operational amplifier A1. An initial voltage V0 is obtained at the source of the NMOS transistor M1, and the magnitude of the initial voltage V0 can be adjusted and controlled by the N-bit digital code. At the same time, the least significant bit (LSB) or resolution reconfigurability of the voltage feedback module 5 is realized. Assuming that the current flowing through the first resistor R1 is n×I0, where n is an integer from 0 to N, then one LSB of the voltage feedback module 5 can be represented as:

[0046]

[0047] More in detail, such as Figure 3As shown, the voltage divider unit 52 includes a second resistor R2 and four third resistors R0. The working voltage VDD is connected to the drain of the NMOS transistor M1 after passing through the first, second, third, and fourth third resistors R0 connected in series. The source of the NMOS transistor M1 is grounded after passing through the second resistor R2 connected in series. The end of the first third resistor R0 closest to the working voltage VDD outputs the initial feedback voltage VF1. The common terminal of the first and second third resistors R0 outputs the initial feedback voltage VF2. The common terminal of the second and third third resistors R0 outputs the initial feedback voltage VF3. The common terminal of the third and fourth third resistors R0 outputs the initial feedback voltage VF4. The end of the fourth third resistor R0 closest to the NMOS transistor M1 outputs the initial feedback voltage VF5.

[0048] More in detail, such as Figure 3 As shown, voltage divider unit 52 performs voltage division processing based on ground, operating voltage VDD, and initial voltage V0 to obtain and output five initial feedback voltages VF1 to VF5 of different magnitudes. The number and value of the voltage divider resistors in voltage divider unit 52 can be selected according to actual needs and are not limited here. Figure 3 The five initial feedback voltages VF1 to VF5 correspond exactly to the four-digit thermometer code DN.

[0049] More in detail, such as Figure 3 As shown, the output selection unit 53 includes a data selector MUX and a second operational amplifier A2. The five input terminals of the data selector MUX are connected one-to-one with five initial feedback voltages VF1 to VF5. The control terminal of the data selector MUX is connected to the thermometer code DN. The output terminal of the data selector MUX is connected to the non-inverting input terminal of the second operational amplifier A2, and the inverting input terminal of the second operational amplifier A2 is connected to its output terminal. The output terminal of the second operational amplifier A2 outputs the feedback voltage V. OUT .

[0050] More in detail, such as Figure 3 As shown, the data selector MUX selects the output of each initial feedback voltage input. Its control method is as follows: if there are i high levels in the input thermometer code DN, then the data selector MUX outputs the i-th initial feedback voltage. This initial feedback voltage is processed by the follower output of the second operational amplifier A2 to obtain the feedback voltage V. OUT .

[0051] More in detail, such as Figure 3 As shown, the voltage feedback module 5 also includes an output common-mode regulation unit 54. The output terminal of the output common-mode regulation unit 54 is connected to the voltage divider unit 52. The output common-mode regulation unit 54 regulates the feedback voltage V. OUTThe common mode value is used for stable clamping.

[0052] More in detail, such as Figure 3 As shown, the output common-mode adjustment unit 54 includes a third operational amplifier A3 and a PMOS transistor M2. The source of the PMOS transistor M2 is connected to the operating voltage VDD, the gate of the PMOS transistor M2 is connected to the output terminal of the third operational amplifier A3, the inverting input terminal of the third operational amplifier A3 is connected to the reference voltage VREF, the non-inverting input terminal of the third operational amplifier A3 is connected to the common terminal of the second and third resistors R0, and the drain of the PMOS transistor M2 is connected to the end of the first resistor R0 away from the second resistor R0.

[0053] More in detail, such as Figure 3 As shown, the virtual short-circuit effect of the third operational amplifier A3 stabilizes the initial feedback voltage VF3 at the reference voltage VREF. Since the initial feedback voltage VF3 is the median voltage of the entire voltage divider unit 52, the feedback voltage V... OUT The common-mode value is stably clamped at VREF.

[0054] In detail, Figure 1 The continuous-time bandpass Sigma-Delta modulator shown is a cascade resonator feedback (CRFB) structure, and its working principle is as follows:

[0055] The loop filter in the continuous-time bandpass Sigma-Delta modulator is composed of an inductor-capacitor resonator. Unlike an active RC resonator, the two integral state variables of this resonator are a voltage signal (x1) and a current signal (x2), which are the voltage across capacitor C and the current across inductor L, respectively. Therefore, the state equation for this loop filter is:

[0056]

[0057] Where K1 is the current amplification factor of the current feedback module 4, K2 is the voltage amplification factor of the voltage feedback module 5, y is the input of the sampling quantizer 3, and v is the output of the sampling quantizer 3.

[0058] Taking the Laplace transform of the above system of equations yields:

[0059]

[0060] Therefore, the ABCD matrix of the modulator is:

[0061]

[0062] Furthermore, the general system block diagram of a continuous-time bandpass Sigma-Delta modulator with a cascaded resonator feedback structure is as follows: Figure 4 As shown, its detailed structural parameters can be found in existing technologies and will not be repeated here. Its sampling clock frequency is generally a normalized 1Hz. The Laplace transform of the modulator state equation of this cascaded resonator feedback structure is as follows:

[0063]

[0064] Therefore, the ABCD matrix of the modulator is:

[0065]

[0066] By comparing the ABCD matrix of the continuous-time bandpass Sigma-Delta modulator of the present invention represented by Equation (4) with the ABCD matrix of the continuous-time bandpass Sigma-Delta modulator of the general cascaded resonator feedback structure represented by Equation (6), it can be seen that by configuring appropriate loop filter parameters (such as the inductance value of inductor L, the capacitance value of inductor C, the LSB of current feedback module 4, the LSB of voltage feedback module 5, and the transconductance g of transconductance operational amplifier), m Equations (4) and (6) are completely equivalent. That is, by configuring appropriate loop filter parameters, the continuous-time bandpass sigma-delta modulator based on inductor-capacitor resonator of the present invention can realize any bandpass sigma-delta modulator noise transfer function.

[0067] Therefore, in this invention, a continuous-time bandpass Sigma-Delta modulator is designed by combining a transconductance operational amplifier, a passive resonator, a sampling quantizer, a current feedback module, and a voltage feedback module. Voltage feedback is added to the conventional current feedback, enabling simultaneous current and voltage feedback and increasing the feedback degree of freedom. This allows the entire modulator to achieve any bandpass Sigma-Delta modulator noise transfer function, effectively solving the performance limitations of continuous-time bandpass Sigma-Delta modulator systems based on inductor-capacitor resonators due to the lack of feedback degree of freedom, and improving the modulator's performance.

[0068] This invention is also applicable to other quantizers of different levels or to continuous-time bandpass Sigma-Delta modulators with multiple inductor-capacitor resonators.

[0069] Furthermore, the present invention also provides an electronic device comprising the continuous-time bandpass Sigma-Delta modulator as described above. Based on the design of current feedback plus voltage feedback in the continuous-time bandpass Sigma-Delta modulator, the feedback degree of freedom is increased, enabling the entire modulator to realize any bandpass Sigma-Delta modulator noise transfer function. This effectively solves the limitation on the performance of the continuous-time bandpass Sigma-Delta modulator system based on inductor-capacitor resonators due to the lack of feedback degree of freedom, thereby improving the performance of the modulator and the overall performance of the electronic device.

[0070] In summary, the continuous-time bandpass Sigma-Delta modulator and electronic device provided by this invention incorporates a transconductance operational amplifier, a passive resonator, a sampling quantizer, a current feedback module, and a voltage feedback module. By adding voltage feedback to the conventional current feedback, it can simultaneously achieve both current and voltage feedback, increasing the feedback degree of freedom. This allows the entire modulator to achieve any noise transfer function of the bandpass Sigma-Delta modulator, effectively solving the performance limitations of the continuous-time bandpass Sigma-Delta modulator system based on inductor-capacitor resonators due to the lack of feedback degree of freedom, and improving the modulator's performance.

[0071] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A continuous-time bandpass Sigma-Delta modulator, characterized in that, include: A transconductance operational amplifier is used to receive an input voltage signal and convert the input voltage signal to obtain and output a current signal. A passive resonator, acting as a loop filter, is connected to the output of the transconductance operational amplifier to convert the current signal and obtain and output an intermediate voltage signal. A sampling quantizer, connected to the output of the passive resonator, samples and quantizes the intermediate voltage signal to obtain and output the thermometer code. The current feedback module has its input terminal connected to the output terminal of the sampling quantizer and its output terminal connected to the passive resonator, and provides feedback current to the passive resonator under the control of the thermometer code; The voltage feedback module has its input terminal connected to the output terminal of the sampling quantizer and its output terminal connected to the passive resonator, and provides feedback voltage to the passive resonator under the control of the thermometer code; The passive resonator includes a capacitor and an inductor. One end of the capacitor is connected to the output terminal of the transconductance operational amplifier, and the other end of the capacitor is grounded. One end of the inductor is connected to the output terminal of the transconductance operational amplifier, and the other end of the inductor is connected to the output terminal of the sampling quantizer after passing through the voltage feedback module connected in series. The end of the inductor connected to the output terminal of the transconductance operational amplifier outputs the intermediate voltage signal.

2. The continuous-time bandpass Sigma-Delta modulator according to claim 1, characterized in that, The thermometer code includes a four-digit thermometer code. The current feedback module includes a first current source, a second current source, a third current source, a fourth current source, a fifth current source, a first switch, a second switch, a third switch, and a fourth switch. The operating voltage is grounded after passing through the first current source, the first switch, and the second current source connected in series. The operating voltage is also grounded after passing through the first current source, the second switch, and the third current source connected in series. The operating voltage is also grounded after passing through the first current source, the third switch, and the fourth current source connected in series. The control terminal of the first switch is connected to the first digit of the four-digit thermometer code. The control terminal of the second switch is connected to the second digit of the four-digit thermometer code. The control terminal of the third switch is connected to the third digit of the four-digit thermometer code. The control terminal of the fourth switch is connected to the fourth digit of the four-digit thermometer code. The common terminal of the first switch, the second switch, the third switch, and the fourth switch outputs the feedback current, which is connected to the output terminal of the transconductance operational amplifier.

3. The continuous-time bandpass Sigma-Delta modulator according to claim 2, characterized in that, The voltage feedback module includes an output voltage adjustment unit, a voltage divider unit, and a selection output unit. The output voltage adjustment unit outputs an adjustable initial voltage. The input terminal of the voltage divider unit is connected to the output terminal of the output voltage adjustment unit. The voltage divider unit performs voltage division processing on ground, the operating voltage, and the initial voltage to obtain and output multiple initial feedback voltages of different magnitudes. The multiple input terminals of the selection output unit are connected one-to-one with the multiple initial feedback voltages. The control terminal of the selection output unit is connected to the thermometer code. Under the control of the thermometer code, the selection output unit selects one of the multiple initial feedback voltages as the feedback voltage and outputs it. The output terminal of the selection output unit is connected to the end of the inductor furthest from the transconductance operational amplifier.

4. The continuous-time bandpass Sigma-Delta modulator according to claim 3, characterized in that, The output voltage regulation unit includes N reference current sources, N digitally controlled switches, a first resistor, a first operational amplifier, and an NMOS transistor. The N reference current sources and the N digitally controlled switches form N parallel current branches. Each current branch includes one reference current source and one digitally controlled switch connected in series. The end of each reference current source furthest from the digitally controlled switch is connected to the operating voltage. The control terminals of the N digitally controlled switches are connected one-to-one with the N bits of the N-bit digital code. The ends of the N digitally controlled switches furthest from the reference current sources are short-circuited and connected to one end of the first resistor. The other end of the first resistor is grounded. The non-inverting input terminal of the first operational amplifier is connected to the common terminal of the N digitally controlled switches. The inverting input terminal of the first operational amplifier is connected to the source of the NMOS transistor. The output terminal of the first operational amplifier is connected to the gate of the NMOS transistor. The source of the NMOS transistor outputs the initial voltage. Here, N is an integer greater than or equal to 2.

5. The continuous-time bandpass Sigma-Delta modulator according to claim 4, characterized in that, The voltage divider unit includes a second resistor and four third resistors. The operating voltage is connected to the drain of the NMOS transistor via the first, second, third, and fourth third resistors connected in series. The source of the NMOS transistor is grounded via the second resistor connected in series. The end of the first third resistor closest to the operating voltage outputs an initial feedback voltage. The common terminal of the first and second third resistors outputs an initial feedback voltage. The common terminal of the second and third third resistors outputs an initial feedback voltage. The common terminal of the third and fourth third resistors outputs an initial feedback voltage. The end of the fourth third resistor closest to the NMOS transistor outputs an initial feedback voltage.

6. The continuous-time bandpass Sigma-Delta modulator according to claim 5, characterized in that, The selection output unit includes a data selector and a second operational amplifier. The five input terminals of the data selector are connected one-to-one with the five initial feedback voltages. The control terminal of the data selector is connected to the thermometer code. The output terminal of the data selector is connected to the non-inverting input terminal of the second operational amplifier. The inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier. The output terminal of the second operational amplifier outputs the feedback voltage.

7. The continuous-time bandpass Sigma-Delta modulator according to claim 5, characterized in that, The voltage feedback module further includes an output common-mode adjustment unit, the output of which is connected to the voltage divider unit, and the output common-mode adjustment unit stabilizes and clamps the common-mode value of the feedback voltage.

8. The continuous-time bandpass Sigma-Delta modulator according to claim 7, characterized in that, The output common-mode adjustment unit includes a third operational amplifier and a PMOS transistor. The source of the PMOS transistor is connected to the operating voltage, the gate of the PMOS transistor is connected to the output terminal of the third operational amplifier, the inverting input terminal of the third operational amplifier is connected to the reference voltage, the non-inverting input terminal of the third operational amplifier is connected to the common terminal of the second and third third resistors, and the drain of the PMOS transistor is connected to the end of the first third resistor away from the second third resistor.

9. An electronic device, characterized in that, Includes the continuous-time bandpass Sigma-Delta modulator as described in any one of claims 1-8.

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