Analog front end circuit, arbitrary waveform generator, quantum measurement and control system and device

Abstract

The utility model discloses analog front-end circuit, arbitrary waveform generator, quantum measurement and control system and equipment for signal processing technical field. In the analog front-end circuit, the input of current voltage module is connected with the output of digital analog converter, and the output of current voltage module is connected with the input of difference to single end module, the output of difference to single end module is connected with the input of first switch, the first output of first switch is connected with the input of gain amplification module, the second output of first switch and the output of gain amplification module are connected with the input of second switch, and the output of second switch is connected with the output of analog front-end circuit, the first switch can select switching the input of first switch and the first output of first switch conduction, or switching the input of first switch and the second output of first switch conduction under the control of control unit, can satisfy the signal demand of multiple amplitude levels of the load of analog front-end circuit.

Description

Technical Field

[0001] This application relates to the field of signal processing technology, and in particular to analog front-end circuits, arbitrary waveform generators, quantum measurement and control systems and devices. Background Technology

[0002] An arbitrary waveform generator (AWG) is a signal source whose core function is to generate non-periodic, programmable waveform signals. An AWG contains a digital-to-analog converter (DAC) and analog front-end circuitry, which amplifies the weakly driven analog signal output from the DAC into a strongly driven analog signal.

[0003] In existing analog front-end circuits, differential analog signals are converted into single-ended analog signals, which are then amplified by an amplifier circuit before being output. However, the output signal amplitude of the analog front-end circuit is limited by the hardware in the amplifier circuit, resulting in a fixed amplitude level. This makes it difficult to meet the signal requirements of multiple amplitude levels of the load driven by the analog front-end circuit. Utility Model Content

[0004] In view of the above problems, this utility model is proposed to provide an analog front-end circuit, an arbitrary waveform generator, a quantum measurement and control system, and a quantum computing device that overcomes or at least partially solves the above problems, and can meet the signal requirements of multiple amplitude levels of the load driven by the analog front-end circuit.

[0005] This utility model provides an analog front-end circuit, including: a current-to-voltage module, a differential-to-single-ended module, a first switch, a second switch, and a gain amplification module;

[0006] The input terminal of the current-to-voltage module is connected to the output terminal of the digital-to-analog converter, and the output terminal of the current-to-voltage module is connected to the input terminal of the differential-to-single-ended module.

[0007] The output terminal of the differential-to-single-ended module is connected to the input terminal of the first switch; the first output terminal of the first switch is connected to the input terminal of the gain amplification module; the second output terminal of the first switch and the output terminal of the gain amplification module are connected to the input terminal of the second switch; the output terminal of the second switch is connected to the output terminal of the analog front-end circuit; the output terminal of the analog front-end circuit is grounded.

[0008] Under the control of the control unit, the first switch can selectively switch the input terminal of the first switch to be connected to the first output terminal of the first switch, or switch the input terminal of the first switch to be connected to the second output terminal of the first switch.

[0009] Furthermore, the output of the analog front-end circuit is connected to the quantum bit; when the quantum bit is in an idle state, the control unit controls the second switch to open.

[0010] Furthermore, the differential-to-single-ended module includes a first amplification unit; the gain amplification module includes a second amplification unit and a gain potentiometer.

[0011] The input terminal of the first amplification unit is connected to the output terminal of the current-to-voltage module, and the output terminal of the first amplification unit is connected to the input terminal of the first switch.

[0012] The non-inverting input terminal of the second amplification unit is connected to the first output terminal of the first switch, the inverting input terminal of the second amplification unit is connected to the output terminal of the second amplification unit via the gain potentiometer, and the output terminal of the second amplification unit is connected to the input terminal of the second switch.

[0013] Furthermore, the gain potentiometer includes: a first adjustable resistor and a second adjustable resistor;

[0014] One end of the first adjustable resistor is grounded, and the other end of the first adjustable resistor is connected to the inverting input terminal of the second amplification unit and one end of the second adjustable resistor.

[0015] The other end of the second adjustable resistor is connected to the output terminal of the second amplification unit.

[0016] Furthermore, the first amplification unit and the second amplification unit are integrated into a dual-stage amplification chip, and the first switch and the second switch are integrated into a dual-channel switch;

[0017] The first input terminal of the dual-channel switch is connected to the output terminal of the first amplification unit, and the first output terminal of the dual-channel switch is connected to the output terminal of the analog front-end circuit.

[0018] The second output terminal of the dual-channel switch is connected to the non-inverting input terminal of the second amplification unit, and the second input terminal of the dual-channel switch is connected to the output terminal of the second amplification unit.

[0019] The dual-channel switch is used to switch the first input terminal of the dual-channel switch to be connected to the first output terminal of the dual-channel switch, or to switch the first input terminal of the dual-channel switch to be connected to the second output terminal of the dual-channel switch, and the second input terminal of the dual-channel switch to be connected to the first output terminal of the dual-channel switch.

[0020] Furthermore, the slew rate of the first amplification unit and the second amplification unit is higher than the preset slew rate;

[0021] And / or, the parasitic capacitance in the analog front-end circuit is less than a preset capacitance value.

[0022] Furthermore, the analog front-end circuit also includes: an EQ equalizer;

[0023] The input terminal of the EQ equalizer is connected to the output terminal of the current-to-voltage module, and the output terminal of the EQ equalizer is connected to the input terminal of the differential-to-single-ended module.

[0024] The EQ equalizer is used to perform frequency compensation on the differential analog voltage signal.

[0025] Furthermore, the analog front-end circuit also includes: a first source resistor and / or a second source resistor, wherein both the first source resistor and the second source resistor include multiple resistors connected in series and a capacitor connected in parallel with the resistor;

[0026] One end of the first source resistor is connected to the output terminal of the differential-to-single-ended module, and the other end of the first source resistor is connected to the input terminal of the first switch.

[0027] One end of the second source resistor is connected to the output terminal of the gain amplification module, and the other end of the second source resistor is connected to the input terminal of the second switch.

[0028] Furthermore, the current-to-voltage module includes: a target power supply, a first conversion resistor, and a second conversion resistor; the noise value of the target power supply is less than a preset noise threshold, and / or, the target power supply is connected to multiple grounding capacitors;

[0029] The target power supply is connected to one end of the first conversion resistor and one end of the second conversion resistor;

[0030] The other end of the first conversion resistor is connected to the non-inverting output of the digital-to-analog converter, and the other end of the second conversion resistor is connected to the inverting output of the digital-to-analog converter.

[0031] Furthermore, the resistors in the analog front-end circuit are precision resistors with a resistance value accuracy less than a preset accuracy threshold.

[0032] Furthermore, the analog front-end circuit also includes: a mirror filter module and / or a harmonic filter module;

[0033] The input terminal of the mirror filter module is connected to the output terminal of the current-to-voltage module, and the output terminal of the mirror filter module is connected to the input terminal of the differential-to-single-ended module.

[0034] The input terminal of the harmonic filtering module is connected to the output terminal of the second switch, and the output terminal of the harmonic filtering module is connected to the input terminal of the analog front-end circuit.

[0035] This invention also provides an arbitrary waveform generator, comprising: a digital-to-analog converter and the aforementioned analog front-end circuit, wherein the output terminal of the digital-to-analog converter is connected to the output terminal of the analog front-end circuit.

[0036] This utility model also provides a quantum measurement and control system, including the analog front-end circuit described above, or including the arbitrary waveform generator described above; the analog front-end circuit or the arbitrary waveform generator is used to control the conduction state of the first switch in the analog front-end circuit through the control unit based on the signal requirements of the quantum bit, and output the corresponding control signal to the quantum bit to manipulate the quantum bit.

[0037] This utility model also provides a quantum computing device, including the analog front-end circuit described above, or including the arbitrary waveform generator described above, or including the quantum measurement and control system described above;

[0038] The quantum chip of the quantum computing device includes multiple qubits, each of which is connected to the output of a different analog front-end circuit. When there is a target qubit in an idle state among the multiple qubits, the control unit controls the second switch in the analog front-end circuit corresponding to the target qubit to be turned off, so as to isolate the thermal noise of the circuit when the channel corresponding to the target qubit is idle and avoid idle disturbance between adjacent channels corresponding to the multiple qubits.

[0039] As can be seen from the above technical solutions, this utility model has the following advantages:

[0040] In this invention, the analog front-end circuit includes: a current-to-voltage module, a differential-to-single-ended module, a first switch, a second switch, and a gain amplification module; the input terminal of the current-to-voltage module is connected to the output terminal of the digital-to-analog converter, and the output terminal of the current-to-voltage module is connected to the input terminal of the differential-to-single-ended module; the output terminal of the differential-to-single-ended module is connected to the input terminal of the first switch, the first output terminal of the first switch is connected to the input terminal of the gain amplification module, the second output terminal of the first switch and the output terminal of the gain amplification module are connected to the input terminal of the second switch, and the output terminal of the second switch is connected to the output terminal of the analog front-end circuit; the output terminal of the analog front-end circuit is grounded; under the control of the control unit, the first switch can selectively switch the input terminal of the first switch to be connected to the first output terminal of the first switch, or switch the input terminal of the first switch to be connected to the second output terminal of the first switch.

[0041] As can be seen, by switching the first switch, the output signal amplitude of the analog front-end circuit can be switched to the output signal amplitude of the differential-to-single-ended module, or to the output signal amplitude after gain amplification by the gain amplification module; that is, by switching the first switch, the output terminal of the analog front-end circuit can output multiple amplitude levels of output signals, which can meet the signal requirements of multiple amplitude levels of the load driven by the analog front-end circuit. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0043] Figure 1 This is a block diagram of an analog front-end circuit disclosed in this utility model;

[0044] Figure 2 for Figure 1 Based on this, the block diagrams of the differential-to-single-ended conversion module and the gain amplification module are further refined;

[0045] Figure 3 for Figure 1 Based on this, add some circuit module block diagrams;

[0046] Figure 4 for Figure 3 Circuit structure diagram of the middle circuit module;

[0047] Figure 5 for Figure 3 The circuit structure diagram of another part of the circuit module;

[0048] Figure 6 This is a schematic diagram showing the output frequency of a digital-to-analog converter disclosed in this utility model. Detailed Implementation

[0049] To enable those skilled in the art to better understand the present application, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present application.

[0050] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0051] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0052] Existing arbitrary waveform generators (AWGs) include a digital-to-analog converter (DAC) and an analog front-end circuit. In the analog front-end circuit, the differential analog signal output from the DAC is converted into a single-ended analog signal, which is then amplified by an amplifier circuit before being output. However, the output signal amplitude of the analog front-end circuit is limited by the hardware in the amplifier circuit, resulting in a fixed amplitude level. This makes it difficult to meet the signal requirements of multiple amplitude levels of the load driven by the analog front-end circuit. Therefore, this invention provides an analog front-end circuit that can meet the signal requirements of multiple amplitude levels of the load driven by the analog front-end circuit, such as... Figure 1 As shown, the details are as follows:

[0053] In this invention, the analog front-end circuit includes: a current-to-voltage module 100, a differential-to-single-ended module 200, a first switch 300, a second switch 400, and a gain amplification module 500; wherein, the first switch 300 and the second switch 400 can be, for example, relays or thyristors, and are not specifically limited here. The control unit (not shown in the figure) can switch the channels in the switches to be on or off by controlling the switches.

[0054] The input terminal of the current-to-voltage module 100 is connected to the output terminal of a digital-to-analog converter (DAC) (not shown), and the output terminal of the current-to-voltage module 100 is connected to the input terminal of the differential-to-single-ended module 200. The current-to-voltage module 100 converts the analog current signal output from the DAC into an analog voltage signal. This current-to-voltage module 100 may include, for example, a resistor or an operational amplifier; the current-to-voltage conversion can be achieved through a resistor or an operational amplifier, and the specific method is not limited here. The differential-to-single-ended module 200 (D2S) converts a differential signal into a single-ended signal. It can be understood that the analog current signal output by the DAC is a differential analog current signal, and the corresponding converted analog voltage signal is a differential analog voltage signal; therefore, the differential-to-single-ended module 200 is needed to convert the differential analog voltage signal into a single-ended analog voltage signal. The differential-to-single-ended module 200 may include, for example, an operational amplifier, a transformer, or a programmable logic device (such as an FPGA or CPLD). The differential signal can be converted into a single-ended signal through the operational amplifier, transformer, or programmable logic device. The specific details are not limited here.

[0055] The first switch 300 is a multiplexer with multiple input and output terminals. The output terminal of the differential-to-single-ended module 200 is connected to the input terminal of the first switch 300. The first output terminal of the first switch 300 is connected to the input terminal of the gain amplifier module 500. The second output terminal of the first switch 300 and the output terminal of the gain amplifier module 500 are both connected to the input terminal of the second switch 400. The output terminal of the second switch 400 is connected to the output terminal of the analog front-end circuit. It can be understood that the gain amplifier module 500 is used to amplify the single-ended analog voltage signal, increasing the signal amplitude. The corresponding gain amplification factor can be a fixed gain or a variable gain; this is not limited here. When it is a variable gain, the gain amplifier module can be a variable gain amplifier (VGA), which can adjust the gain amplification factor according to the load requirements. The gain amplifier module 500 can be a gain amplifier circuit composed of operational amplifiers or an amplifier circuit composed of transistors; this is not limited here.

[0056] The output terminal of the analog front-end circuit is grounded. It is understood that the output terminal of the analog front-end circuit is often connected to an external interface and is susceptible to static electricity or surge impacts from the external interface. By grounding the output terminal of the analog front-end circuit, the static current or transient current of the surge can be flowed into the ground, avoiding static electricity or surge impacts on the analog front-end circuit and protecting the analog front-end circuit.

[0057] Under the control of the control unit, the first switch 300 can selectively switch the input terminal of the first switch 300 to be connected with the first output terminal of the first switch 300, or switch the input terminal of the first switch 300 to be connected with the second output terminal of the first switch 300. It can be understood that when the input terminal of the first switch 300 is connected to the first output terminal, the single-ended analog voltage signal transmitted from the differential-to-single-ended module 200 is amplified by the gain amplifier module 500 after passing through the first output terminal of the first switch 300, and then output to the second switch 400. After being combined by the second switch 400, the signal is output from the output terminal of the analog front-end circuit. At this time, the output signal amplitude of the analog front-end circuit is the same as the output signal amplitude after being amplified by the gain amplifier module 500. When the input terminal of the first switch 300 is switched to be connected to the second output terminal of the first switch 300, the single-ended analog voltage signal transmitted from the differential-to-single-ended module 200 is directly output to the second switch 400 through the second output terminal of the first switch 300. At this time, the output signal amplitude of the analog front-end circuit is the output signal amplitude of the differential-to-single-ended module 200, that is, the signal that has not been amplified by the gain amplifier module 500.

[0058] As can be seen, in this invention, the analog front-end circuit has two output stages (two outputs): one is an output amplification stage, which is amplified by the gain amplification module 500 before output; the other is a direct-through stage, outputting directly. Switching is achieved via the first switch 300, and the performance of these two output stages does not affect each other. Furthermore, in this invention, the analog front-end circuit can control the first switch 300 to switch to the corresponding output based on the signal requirements of the load. When the signal requirement is a low-noise signal, the input terminal of the first switch 300 can be switched to the second output terminal of the first switch 300. In this case, the single-ended analog voltage signal does not pass through the gain amplification module 500, reducing noise interference from the gain amplification module 500. When the signal requirement is a high-amplitude signal, the input terminal of the first switch 300 can be switched to the first output terminal of the first switch 300. In this case, the single-ended analog voltage signal is amplified by the gain amplification module 500, and the amplified signal is output.

[0059] As can be seen, in this utility model, the analog front-end circuit includes: a current-to-voltage module, a differential-to-single-ended module, a first switch, a second switch, and a gain amplification module; the input terminal of the current-to-voltage module is connected to the output terminal of the digital-to-analog converter, and the output terminal of the current-to-voltage module is connected to the input terminal of the differential-to-single-ended module; the output terminal of the differential-to-single-ended module is connected to the input terminal of the first switch, the first output terminal of the first switch is connected to the input terminal of the gain amplification module, the second output terminal of the first switch and the output terminal of the gain amplification module are both connected to the input terminal of the second switch, and the output terminal of the second switch is connected to the output terminal of the analog front-end circuit; under the control of the control unit, the first switch can selectively switch the input terminal of the first switch to be connected to the first output terminal of the first switch, or switch the input terminal of the first switch to be connected to the second output terminal of the first switch.

[0060] By switching the first switch, the output signal amplitude of the analog front-end circuit can be switched to the output signal amplitude of the differential-to-single-ended module, or to the output signal amplitude after gain amplification by the gain amplification module; that is, by switching the first switch, the output terminal of the analog front-end circuit can output multiple amplitude levels of output signals, which can meet the signal requirements of multiple amplitude levels of the load driven by the analog front-end circuit.

[0061] Furthermore, the analog front-end circuit of this invention can be applied to the field of quantum computing. The output of the analog front-end circuit is connected to the qubit, and various amplitude-level control signals can be output to the qubit to manipulate it. When the qubit is in an idle state, i.e., a standby state when it is not read or invoked, the control unit can control the second switch 400 to open. It is understood that opening the second switch 400 disconnects the control signals output by the analog front-end circuit to the qubit. At this time, the idle qubit does not receive control signals, effectively preventing interference from other qubits in operation and achieving noise isolation of the idle channel corresponding to the idle qubit.

[0062] Optional, such as Figure 2 As shown, in one embodiment, the differential-to-single-ended module 200 includes, for example, a first amplification unit 201, and the gain amplification module 500 includes, a second amplification unit 501 and a gain potentiometer 502; wherein, the first amplification unit 201 and the second amplification unit 501 can be operational amplifiers.

[0063] The input terminal of the first amplification unit 201 is connected to the output terminal of the current-to-voltage module 100, and the output terminal of the first amplification unit 201 is connected to the input terminal of the first switch 300. It is understood that the differential analog current signal output by the digital-to-analog converter has a large common-mode voltage (such as noise or power supply offset), meaning the differential analog voltage signal output by the current-to-voltage module 100 has a large common-mode voltage. The first amplification unit 201 is used to separate the differential-mode voltage (effective signal) and common-mode voltage in the differential analog voltage signal and remove the DC bias, thus converting the differential analog voltage signal with common-mode voltage into a single-ended analog voltage signal with zero bias (i.e., the signal baseline is at zero potential).

[0064] The non-inverting input of the second amplification unit 501 is connected to the first output of the first switch 300. The inverting input of the second amplification unit 501 is connected to its output via a gain potentiometer 502. The output of the second amplification unit 501 is connected to the input of the second switch 400. The gain potentiometer 502 can be composed of resistors. It is understood that the gain amplification factor of the gain amplification module 500 is determined based on the potential in the gain potentiometer 502; the larger the potential in the gain potentiometer 502, the larger the gain amplification factor of the corresponding gain amplification module 500; the smaller the potential in the gain potentiometer 502, the smaller the gain amplification factor of the corresponding gain amplification module 500.

[0065] Furthermore, to flexibly achieve controllable gain, the gain potentiometer 502 is an adjustable potentiometer, allowing for flexible adjustment of the signal amplitude of the output signal from the analog front-end circuit through gain changes. Optionally, such as... Figure 4 As shown, the gain potentiometer 502 includes, for example, a first adjustable resistor R8 and a second adjustable resistor R9; one end of the first adjustable resistor R8 is grounded, and the other end of the first adjustable resistor R8 is connected to the inverting input terminal of the second amplification unit Q2 and one end of the second adjustable resistor R9; the other end of the second adjustable resistor R9 is connected to the output terminal of the second amplification unit Q2.

[0066] Furthermore, to achieve a compact analog front-end circuit, multiple amplitude levels of output signals are implemented using as few components as possible. In this invention, the first and second amplification units can be integrated into a dual-stage amplification chip, and the first and second switches can be integrated into a dual-channel switch (which can be a dual-channel relay). Through a dual-stage amplification chip and a dual-channel switch, an analog front-end circuit that outputs multiple amplitude levels of output signals from a single output port is realized.

[0067] like Figure 4As shown, the first amplification unit and the second amplification unit are integrated into a dual-stage amplifier chip U1. The first amplification unit in the dual-stage amplifier chip U1 mainly includes an operational amplifier Q1, and the second amplification unit mainly includes an operational amplifier Q2. The first positive power supply pin +VCC1 and the second positive power supply pin +VCC2 of the dual-stage amplifier chip U1 are connected to a voltage source of +7.0V, and the first negative power supply pin -VCC1 and the second negative power supply pin -VCC2 of the dual-stage amplifier chip U1 are connected to a voltage source of -7.0V. The differential analog voltage signal output by the current-to-voltage module 100 is transmitted to the operational amplifier Q1 via the first non-inverting input pin +NI and the first inverting input pin -NI of the dual-stage amplifier chip U1. The DC bias voltage VBIAS provided by the active device is transmitted to the non-inverting input terminal of the operational amplifier Q1 via the input pin VMID_IN of the common-mode voltage reference of the dual-stage amplifier chip U1, the output pin VMID_OUT of the common-mode voltage reference of the dual-stage amplifier chip U1, and the feedback pin VREF of the dual-stage amplifier chip U1 to suppress the common-mode voltage in the differential analog voltage signal. The output of operational amplifier Q1 is connected to the first output pin VO1 of dual-stage amplifier chip U1.

[0068] The three ports of switch K1 in the dual-stage amplifier chip U1 are connected to the output of operational amplifier Q1, the second non-inverting input of dual-stage amplifier chip U1, and the non-inverting input of operational amplifier Q2, respectively. The control terminal of switch K1 is connected to the path selection pin PATHSEL of dual-stage amplifier chip U1. The non-inverting input of operational amplifier Q2 is connected to the ground pin GND of dual-stage amplifier chip U1, and the ground pin GND and the heat sink pin EP of dual-stage amplifier chip U1 are grounded. The inverting input of operational amplifier Q2 is connected to the second inverting input pin VIN- of dual-stage amplifier chip U1, and the output of operational amplifier Q2 is connected to the second output pin VOUT of dual-stage amplifier chip U1. The disable control signal AMP2_DIS0 is input to the control terminal of operational amplifier Q2 via the digital control pin DISABLE of dual-stage amplifier chip U1.

[0069] The first input terminal 2C of the dual-channel switch S1 is connected to the output terminal of the first amplification unit Q1, and the first output terminal 1C of the dual-channel switch S1 is connected to the output terminal SMA_1 of the analog front-end circuit. The second output terminal 2B of the dual-channel switch S1 is connected to the non-inverting input terminal of the second amplification unit Q2, and the second input terminal 1B of the dual-channel switch S1 is connected to the output terminal of the second amplification unit Q2. The dual-channel switch S1 is used to switch the first input terminal 2C of the dual-channel switch S1 to be connected to the first output terminal 1C of the dual-channel switch S1, that is, to switch the first input terminal 2C of the dual-channel switch S1 to be connected to the third output terminal 2A of the dual-channel switch S1, and the third input terminal 1A of the dual-channel switch S1 to be connected to the first output terminal 1C of the dual-channel switch S1; or, to switch the first input terminal 2C of the dual-channel switch S1 to be connected to the second output terminal 2B of the dual-channel switch S1, and the second input terminal 1B of the dual-channel switch S1 to be connected to the first output terminal 1C of the dual-channel switch S1. In the dual-channel switch S1, the first power supply terminal CASE1 and the second power supply terminal CASE2 are grounded. One end is connected to a voltage of 3V3 and a grounding capacitor C11, and the other end is input with the switch control signal AMP2_SW0. The switching of the dual-channel switch S1 is realized through the switch control signal AMP2_SW0.

[0070] In the corresponding two-stage output of the analog front-end circuit, when the output of the analog front-end circuit is direct, the operational amplifier Q2 is stopped by the disable control signal AMP2_DIS0, and the first input terminal 2C of the dual-channel switch S1 is switched to conduct by the switch control signal AMP2_SW0. At this time, the single-ended analog voltage signal output from the output terminal of the operational amplifier Q1 is input to the first input terminal 2C of the dual-channel switch S1, and is directly output to the output terminal of the analog front-end circuit through the first output terminal 1C of the dual-channel switch S1. When the output of the analog front-end circuit is the output amplification stage, the operational amplifier Q2 is started to work by controlling the disable control signal AMP2_DIS0, and the first input terminal 2C and the second output terminal 2B of the dual-channel switch S1 are switched on by the switch control signal AMP2_SW0, and the second input terminal 1B and the first output terminal 1C of the dual-channel switch S1 are switched on. At this time, the single-ended analog voltage signal output from the output terminal of the operational amplifier Q1 is input to the first input terminal 2C of the dual-channel switch S1, and input to the operational amplifier Q2 through the second output terminal 2B of the dual-channel switch S1. The single-ended analog voltage signal is amplified by the gain potentiometer 502 connected to the operational amplifier Q2 and output to the second input terminal 1B of the dual-channel switch S1. The signal is then output to the output terminal of the analog front-end circuit through the first output terminal 1C of the dual-channel switch S1.

[0071] Furthermore, the output signal amplitude range of the analog front-end circuit is relatively large. When the output signal of the analog front-end circuit is a large signal with a large amplitude (>=1Vpp) and a small signal with a small amplitude (=<0.5Vpp), the bandwidth difference between the large and small signals is significant due to the different bandwidth limiting factors. Typically, the bandwidth of the large signal is only about 60% of the bandwidth of the small signal. Here, Vpp is the peak-to-peak voltage of the input signal of the analog front-end circuit, and the signal bandwidth is the difference between the highest and lowest frequencies of the signal, meaning the maximum amplitude of the output signal of the analog front-end circuit decreases linearly with increasing frequency. To ensure the signal bandwidth of the large signal and avoid it being too small, in the analog front-end circuit of this invention, the slew rate of the first amplification unit and the second amplification unit is higher than a preset slew rate; and / or, the parasitic capacitance in the analog front-end circuit is less than a preset capacitance value. The preset slew rate can be 5000V / us or 5500V / us, and is not specifically limited here; the preset capacitance value can be 0.1pF or 0.2pF, and is not specifically limited here.

[0072] Understandably, the bandwidth of a large signal output from an analog front-end circuit is limited by the slew rate of the amplification unit within the circuit. The slew rate is the fastest rate of change of the output signal, measured in V / µs. For example, the formula for the slew rate of an amplification unit within a 3dB bandwidth is:

[0073] SlewRate=(Vpeak / sqrt(2))*2*π*f -3db Equation (1)

[0074] Among them, f -3db The 3dB bandwidth refers to the bandwidth of the large signal; Vpeak is the signal amplitude of the large signal, and Vpeak is 0.5*Vpp. According to equation (1), the formula for the bandwidth of the large signal being limited by the slew rate can be obtained:

[0075] f -3db =sqrt(2)*SlewRate / (Vpeak*2*π) Formula (2)

[0076] When the large signal output by the analog front-end circuit has a frequency of DC-500MHz and a signal amplitude of 5Vpp (peak-to-peak voltage of 5V), then Vpeak = 2.5V; according to equation (1), the corresponding slew rate can be obtained as:

[0077] SlewRate=(Vpeak / sqrt(2))*2*π*f -3db

[0078] =(2.5 / sqrt(2))*2*π*0.5*10^9

[0079] =1.76*6.28*0.5*10^9=5.52*10^9(V / s)=5.52*10^3(V / us).

[0080] Therefore, the slew rate of the first and second amplification units in the analog front-end circuit is higher than 5500V / us.

[0081] Besides the slew rate of the amplification unit, parasitic capacitance in the analog front-end circuit also limits the bandwidth of large signals; the corresponding formula for the current across the parasitic capacitance is:

[0082] Ic(t)=C*dV(t) / dt Equation (3)

[0083] Where C is the parasitic capacitance, V(t) is the instantaneous voltage value of the output signal of the analog front-end, Ic(t) is the current drawn by the parasitic capacitance, and t is time. It can be seen that as the amplitude of the output signal in the analog front-end circuit increases, the current drawn by the parasitic capacitance also increases.

[0084] For a single-tone signal (sine wave signal), V(t) = A*sin(wt), where A represents the amplitude of the signal and ω represents the angular frequency of the signal; combining with equation (3), the current drawn by the corresponding parasitic capacitance is:

[0085] Ic(t)=A*C*w*cos(wt) Equation (4)

[0086] For example, when the output signal of the analog front-end circuit is 500MHz with a swing of 2Vpp, A is 1V, ω is 2*π*0.5*10^9, and the corresponding sine wave signal is 1*Sin(2*π*0.5*10^9*t); combined with equation (4), for a parasitic capacitance of 1pF, the current drawn by it within 1s is:

[0087] Ic(t) = 1 * 10^-12 * 2 * π * 0.5 * 10^9 * cos(2 * π * 0.5 * 10^9 * 1) = 3.14 mA; It can be seen that the analog front-end circuit requires an additional 3.14 mA of current output due to the 1 pF parasitic capacitance. Therefore, in this invention, the parasitic capacitance in the analog front-end circuit is less than the preset capacitance value, minimizing the parasitic capacitance as much as possible.

[0088] Further optional, such as Figure 3As shown, in this invention, the analog front-end circuit further includes, for example, an EQ equalizer 600. The input terminal of the EQ equalizer 600 is connected to the output terminal of the current-to-voltage module 100, and the output terminal of the EQ equalizer 600 is connected to the input terminal of the differential-to-single-ended module 200. The EQ equalizer 600 is used to perform frequency compensation on the differential analog voltage signal output by the current-to-voltage module 100. It can be understood that the EQ equalizer 600 can pre-compensate for high-frequency-related linear losses in the analog front-end circuit. If the linear losses are large at high frequencies, the EQ equalizer 600 can increase the signal gain at high frequencies. By adding an EQ equalizer to the analog front-end circuit, the high-frequency response can be improved, further increasing the bandwidth of the output signal of the analog front-end circuit.

[0089] In one embodiment, such as Figure 5 As shown, the EQ equalizer 600 includes, for example, resistors R3, R4, and R5, capacitors C7 and C8. It uses test points TP1 and TP2 to input the linear loss of high-frequency analog front-end circuits to compensate for the linear loss.

[0090] Furthermore, signal waveform overshoot in the output signal of an analog front-end circuit can easily lead to signal oscillation. This overshoot is strongly correlated with the output impedance of the analog front-end circuit; the lower the output impedance, the more severe the overshoot, and vice versa. The output impedance of the analog front-end circuit is composed of the source impedance of the amplification unit output and the load impedance connected to the output. To make the output signal waveform of the analog front-end circuit smoother and avoid overshoot, the source impedance of the amplification unit output needs to be designed accordingly.

[0091] like Figure 3 As shown, the analog front-end circuit also includes: a first source resistor RS1 and / or a second source resistor RS2; one end of the first source resistor RS1 is connected to the output terminal of the differential-to-single-ended module 200, and the other end of the first source resistor RS1 is connected to the input terminal of the first switch 300; one end of the second source resistor RS2 is connected to the output terminal of the gain amplifier module 500, and the other end of the second source resistor RS2 is connected to the input terminal of the second switch 400. Both the first source resistor RS1 and the second source resistor RS2 include multiple resistors connected in series and capacitors connected in parallel with the resistors. Figure 4As shown, the first source-end resistor RS1 includes resistors R6 and R7 connected in series, and capacitor C9 connected in parallel with resistor R7; the second source-end resistor RS2 includes resistors R10 and R11 connected in series, and capacitor C10 connected in parallel with resistor R11. The first source-end resistor RS1 and the second source-end resistor RS2 form a multi-stage resistor circuit. By lumping and connecting multiple resistors in series to achieve impedance matching of the source-end resistors, the transmission ratio of high-frequency signals can be appropriately improved (i.e., the voltage amplitude obtained by the load connected to the analog front-end circuit is increased), and the signal waveform of the output signal of the analog front-end circuit can be made smoother, thus improving the flatness of the analog front-end circuit and avoiding signal waveform overshoot.

[0092] It is understandable that combining the EQ equalizer 600 with the first source resistor RS1 and / or the second source resistor RS2 in the analog front-end circuit can improve the bandwidth of the output signal while avoiding overshoot of the output signal waveform through frequency compensation.

[0093] Furthermore, when noise exists in the power supply of the analog front-end circuit, this noise can easily interfere with the output of the analog front-end circuit. To achieve a low-noise output signal from the analog front-end circuit, such as... Figure 5 As shown, in this invention, the current-to-voltage module 100 includes: a target power supply AVDD33, a first conversion resistor R1, and a second conversion resistor R2; the target power supply AVDD33 is connected to one end of the first conversion resistor R1 and one end of the second conversion resistor R2; the other end of the first conversion resistor R1 is connected to the non-inverting input OUT+ of the digital-to-analog converter (DAC), and the other end of the second conversion resistor R2 is connected to the inverting input OUT- of the DAC. The target power supply AVDD33 provides differential current to the output of the DAC through the first conversion resistor R1 and the second conversion resistor R2, converting the differential analog current signal output by the DAC into a differential analog voltage signal.

[0094] The target power supply AVDD33 has a noise value less than a preset noise threshold, and / or the target power supply AVDD33 is connected to multiple grounding capacitors C1 and C2; the preset noise threshold can be 0.5μV rms or 0.8μV rms (microvolt root mean square), and is not specifically limited here. The target power supply AVDD33 can be a low-noise LDO (low dropout linear regulator). A low-noise power supply can prevent noise crosstalk from the power supply to the output signal, and / or the multiple grounding capacitors connected to the target power supply can couple noise from the power supply to ground, reducing noise from the power supply and preventing noise crosstalk from the power supply to the output signal. It is understood that in this invention, PI design (power integrity design) can also be performed to reduce the impedance of the PDN (power distribution network) in the operating frequency band, reduce power supply noise, and further prevent noise crosstalk from the power supply to the output signal.

[0095] Furthermore, the analog front-end circuit requires high accuracy in its output signal (e.g., within 1%). To improve this accuracy, the resistors in the analog front-end circuit are precision resistors with a resistance value accuracy less than a preset accuracy threshold. These resistors can be source-end resistors or resistors in various modules. The resistance value accuracy refers to the difference between the actual resistance value and the nominal resistance value. A precision resistor is one whose resistance value is known. The preset accuracy threshold can be 0.1% or 0.2%, and is not specifically limited here. The resistors in the analog front-end circuit can be 0.1% precision resistors with a low temperature coefficient.

[0096] Furthermore, in analog front-end circuits, as the frequency of the output signal increases, the output signal is prone to noise and harmonics. To achieve noise and harmonic suppression, options include... Figure 3 As shown, the analog front-end circuit of this utility model further includes: a mirror filter module 700 and / or a harmonic filter module 800; wherein, the input terminal of the mirror filter module 700 is connected to the output terminal of the current-to-voltage module 100, and the output terminal of the mirror filter module 700 is connected to the input terminal of the differential-to-single-ended module 200; the input terminal of the harmonic filter module 800 is connected to the output terminal of the second switch 400, and the output terminal of the harmonic filter module 800 is connected to the output terminal of the analog front-end circuit.

[0097] It is understandable that the output signal of a digital-to-analog converter, in addition to the main signal component, also contains a mirror image of the main signal with respect to the sampling rate, such as... Figure 6As shown, when the digital-to-analog converter outputs the first Nyquist domain signal in baseband mode, mirror signal components will also exist in the second and third Nyquist domains. This Nyquist frequency is typically 0.5 times the sampling rate of the digital-to-analog converter; the corresponding mirror filtering module can be a low-pass filter with a cutoff frequency of the Nyquist frequency. The low-pass filter filters out the mirror components, thus suppressing noise.

[0098] For harmonic components present in the output signal of the analog front-end circuit, a harmonic filtering module can be used for harmonic filtering. This harmonic filtering module can be a low-pass filter. Figure 4 In the circuit, F1), the cutoff frequency is the highest frequency fop of the output signal's operating frequency band, used to filter second harmonics with frequencies of 0.5*fop and above, and third harmonics with frequencies of 0.33*fop and above, thereby achieving harmonic suppression. In one feasible implementation, by switching the first switch 500, the harmonic filtering module 800 can perform harmonic filtering on both stages of the analog front-end circuit's output (direct output and output after gain amplification), enabling multiplexing of harmonic filtering and making the analog front-end circuit more compact.

[0099] This invention also provides an arbitrary waveform generator, comprising: a digital-to-analog converter (DAC) and the aforementioned analog front-end circuit, wherein the output terminal of the DAC is connected to the input terminal of the analog front-end circuit. The differential analog signal output from the DAC is processed by the analog front-end circuit, allowing multiple amplitude levels of output signals to be output at the output terminal of the analog front-end circuit.

[0100] This invention also provides a quantum measurement and control system, including the aforementioned analog front-end circuit, or the aforementioned arbitrary waveform generator. The analog front-end circuit or the arbitrary waveform generator is used to control the conduction state of a first switch in the analog front-end circuit through a control unit, based on the signal requirements of the qubits, and output corresponding control signals to the qubits to manipulate them. The analog front-end circuit or the arbitrary waveform generator outputs precise control signals to the qubits based on their signal requirements, enabling operations such as initialization, flipping, and reading of the qubits.

[0101] Understandably, when the quantum bit requires a low-noise signal, the input and second output of the first switch can be switched on. In this case, the single-ended analog voltage signal bypasses the gain amplifier module, reducing noise interference from the gain amplifier module and thus reducing noise interference to the quantum bit. When the quantum bit requires a high-amplitude signal, the input and first output of the first switch can be switched on. In this case, the single-ended analog voltage signal is amplified by the gain amplifier module, and the amplified signal is output to the quantum bit.

[0102] This invention also provides a quantum computing device, including the analog front-end circuit described above, or the arbitrary waveform generator described above, or the quantum measurement and control system described above. The quantum chip of the quantum computing device includes multiple qubits, each connected to the output of a different analog front-end circuit. Each qubit outputs a control signal through its corresponding analog front-end circuit. When a target qubit is in an idle state, the control unit controls the second switch in the analog front-end circuit corresponding to the target qubit to open, isolating the thermal noise of the circuit when the target qubit's channel is idle, and preventing idle disturbances between adjacent channels corresponding to multiple qubits. It is understood that opening the second switch disconnects the control signal output by the analog front-end circuit to the target qubit. At this time, the idle target qubit does not receive a control signal, effectively preventing interference from other qubits in operation and achieving noise isolation of the idle channel corresponding to the idle target qubit.

[0103] The analog front-end circuits disclosed in the above embodiments of this application can be applied to the above-mentioned quantum measurement and control system. However, the analog front-end circuits can also be applied to other suitable electronic devices. This application does not limit them. Any analog front-end circuits made based on the inventive concept of this application should fall within the protection scope of this application.

[0104] In this invention, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The term "multiple" refers to two or more unless otherwise expressly defined.

[0105] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model, and they should all be covered within the scope of the claims and specification of this utility model. If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the embodiments of this application. The aforementioned storage media include: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks or optical disks, and other media that can store program code.

Claims

1. An analog front-end circuit, characterized in that, include: Current-to-voltage module, differential-to-single-ended module, first switch, second switch, and gain amplifier module; The input terminal of the current-to-voltage module is connected to the output terminal of the digital-to-analog converter, and the output terminal of the current-to-voltage module is connected to the input terminal of the differential-to-single-ended module. The output terminal of the differential-to-single-ended module is connected to the input terminal of the first switch; the first output terminal of the first switch is connected to the input terminal of the gain amplification module; the second output terminal of the first switch and the output terminal of the gain amplification module are connected to the input terminal of the second switch; the output terminal of the second switch is connected to the output terminal of the analog front-end circuit; the output terminal of the analog front-end circuit is grounded. Under the control of the control unit, the first switch can selectively switch the input terminal of the first switch to be connected to the first output terminal of the first switch, or switch the input terminal of the first switch to be connected to the second output terminal of the first switch.

2. The analog front-end circuit according to claim 1, characterized in that, The output of the analog front-end circuit is connected to the quantum bit; when the quantum bit is in an idle state, the control unit controls the second switch to open.

3. The analog front-end circuit according to claim 1, characterized in that, The differential-to-single-ended module includes: a first amplification unit; the gain amplification module includes: a second amplification unit and a gain potentiometer; The input terminal of the first amplification unit is connected to the output terminal of the current-to-voltage module, and the output terminal of the first amplification unit is connected to the input terminal of the first switch. The non-inverting input terminal of the second amplification unit is connected to the first output terminal of the first switch, the inverting input terminal of the second amplification unit is connected to the output terminal of the second amplification unit via the gain potentiometer, and the output terminal of the second amplification unit is connected to the input terminal of the second switch.

4. The analog front-end circuit according to claim 3, characterized in that, The gain potentiometer includes: a first adjustable resistor and a second adjustable resistor; One end of the first adjustable resistor is grounded, and the other end of the first adjustable resistor is connected to the inverting input terminal of the second amplification unit and one end of the second adjustable resistor. The other end of the second adjustable resistor is connected to the output terminal of the second amplification unit.

5. The analog front-end circuit according to claim 3, characterized in that, The first amplification unit and the second amplification unit are integrated into a dual-stage amplification chip, and the first switch and the second switch are integrated into a dual-channel switch; The first input terminal of the dual-channel switch is connected to the output terminal of the first amplification unit, and the first output terminal of the dual-channel switch is connected to the output terminal of the analog front-end circuit. The second output terminal of the dual-channel switch is connected to the non-inverting input terminal of the second amplification unit, and the second input terminal of the dual-channel switch is connected to the output terminal of the second amplification unit. The dual-channel switch is used to switch the first input terminal of the dual-channel switch to be connected to the first output terminal of the dual-channel switch, or to switch the first input terminal of the dual-channel switch to be connected to the second output terminal of the dual-channel switch, and the second input terminal of the dual-channel switch to be connected to the first output terminal of the dual-channel switch.

6. The analog front-end circuit according to claim 3, characterized in that, The slew rate of the first amplification unit and the second amplification unit is higher than the preset slew rate; And / or, the parasitic capacitance in the analog front-end circuit is less than a preset capacitance value.

7. The analog front-end circuit according to claim 1, characterized in that, The analog front-end circuit also includes: an EQ equalizer; The input terminal of the EQ equalizer is connected to the output terminal of the current-to-voltage module, and the output terminal of the EQ equalizer is connected to the input terminal of the differential-to-single-ended module. The EQ equalizer is used to perform frequency compensation on the differential analog voltage signal.

8. The analog front-end circuit according to claim 1, characterized in that, The analog front-end circuit further includes: a first source resistor and / or a second source resistor, wherein both the first source resistor and the second source resistor include multiple resistors connected in series and a capacitor connected in parallel with the resistors. One end of the first source resistor is connected to the output terminal of the differential-to-single-ended module, and the other end of the first source resistor is connected to the input terminal of the first switch. One end of the second source resistor is connected to the output terminal of the gain amplification module, and the other end of the second source resistor is connected to the input terminal of the second switch.

9. The analog front-end circuit according to claim 1, characterized in that, The current-to-voltage module includes: a target power supply, a first conversion resistor, and a second conversion resistor; the noise value of the target power supply is less than a preset noise threshold, and / or the target power supply is connected to multiple grounding capacitors; The target power supply is connected to one end of the first conversion resistor and one end of the second conversion resistor; The other end of the first conversion resistor is connected to the non-inverting output of the digital-to-analog converter, and the other end of the second conversion resistor is connected to the inverting output of the digital-to-analog converter.

10. The analog front-end circuit according to claim 1, characterized in that, The resistors in the analog front-end circuit are precision resistors with a resistance value accuracy less than a preset accuracy threshold.

11. The analog front-end circuit according to claim 1, characterized in that, The analog front-end circuit further includes: a mirror filter module and / or a harmonic filter module; The input terminal of the mirror filter module is connected to the output terminal of the current-to-voltage module, and the output terminal of the mirror filter module is connected to the input terminal of the differential-to-single-ended module. The input terminal of the harmonic filtering module is connected to the output terminal of the second switch, and the output terminal of the harmonic filtering module is connected to the output terminal of the analog front-end circuit.

12. An arbitrary waveform generator, characterized in that, include: The digital-to-analog converter and the analog front-end circuit according to any one of claims 1 to 11, wherein the output terminal of the digital-to-analog converter is connected to the input terminal of the analog front-end circuit.

13. A quantum measurement and control system, characterized in that, The device includes the analog front-end circuit as described in any one of claims 1 to 11, or the arbitrary waveform generator as described in claim 12; the analog front-end circuit or the arbitrary waveform generator is used to control the conduction state of the first switch in the analog front-end circuit through the control unit based on the signal requirements of the quantum bit, and output a corresponding control signal to the quantum bit to manipulate the quantum bit.

14. A quantum computing device, characterized in that, It includes the analog front-end circuit as described in any one of claims 1 to 11, or the arbitrary waveform generator as described in claim 12, or the quantum measurement and control system as described in claim 13; The quantum chip of the quantum computing device includes multiple qubits, each of which is connected to the output of a different analog front-end circuit. When there is a target qubit in an idle state among the multiple qubits, the control unit controls the second switch in the analog front-end circuit corresponding to the target qubit to be turned off, so as to isolate the thermal noise of the circuit when the channel corresponding to the target qubit is idle and avoid idle disturbance between adjacent channels corresponding to the multiple qubits.

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