Wideband signal generator and wideband signal generation method

Abstract

To generate wideband signals.SOLUTION: A wideband signal generator 30 has one or more DACs 32, each of which having one or more pipes and a sample rate, a multiplexer 38 to receive analog output signals from at least two pipes from the DACs 32 and multiplex the analog output signals and zero into an output stream, a bandpass filter 40 to receive the output stream and filter out frequency components in the output stream that are outside a target frequency band and produce a radio frequency (RF) output signal in the target frequency band, and one or more processors 36. The one or more processors 36 are configured to execute a program that causes the one or more processors 36 to generate digital samples and transfer the digital samples to the one or more DACs 32, and the digital samples are generated to produce analog outputs that cause the RF output signal to match a target RF frequency band.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to test and measurement instruments, and more particularly to wideband signal generating instruments. [Background technology]

[0002] Wired and wireless communications are driving ever-increasingly high-speed signaling. For example, 400Gb (Gigabit) and 800Gb Ethernet are being deployed and developed for data centers to support wireless communications as "backhaul". 5G wireless is being deployed and 6G wireless is being developed. Both 5G and 6G are exploring higher frequency bands. For example, 5G wireless is exploring mmWave frequency bands from 24GHz to 300GHz, and 6G wireless is exploring both mmWave and sub-THz. The radio frequency (RF) range of the signal generator needs to be up to 100GHz or higher.

[0003] As shown in Figure 1, a mobile unit 10 communicates with a base station 12 over an airborne radio channel 14. The base station 12 is connected to a server 16 over a wired channel 18 (eg, an optical cable). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-120374 A [Patent Document 2] JP 2020-113978 A [Non-patent literature]

[0005] [Non-Patent Document 1] "Signal generator" introduction site, Tektronix, [online], [searched July 7, 2024], Internet<https: / / www.tek.com / ja / products / signal-generators> Summary of the Invention [Problem to be solved by the invention]

[0006] To achieve transmission frequencies above 100 GHz, current signal generators usually use mixers to up-convert baseband signals from an arbitrary waveform generator (AWG) to RF bands, as shown in FIG. 2. In FIG. 2, the signal generator is composed of an AWG 20 that generates a baseband signal, and a mixer 22 up-converts it to RF bands. A filter 24 shapes the signal to retain signals in the target RF band and reject out-of-band signals. For signal generators, the mixing signal needs to be adjusted to different frequencies to obtain different target RF bands. Signal generators usually use multiple mixing stages to generate target RF signals in higher frequency bands with wider instantaneous bandwidth (IBW).

[0007] There is a need for a signal generator that can be built with reduced complexity, cost and power consumption. [Means for solving the problem]

[0008] The present embodiment describes a new device called Wideband Signal Generator (WSG), which uses a multiplexer and bandpass filters along with paired digital-to-analog converters (DACs) to generate a wideband RF signal. Conventional mixer approaches require adjusting the frequency of the mixed signal to cover different RF bands. In contrast, the WSG multiplexer operates at a fixed rate. The WSG can be built with less complexity, cost, and power consumption, and allows for a larger number of RF channels in a single device. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 shows a diagram of wired and wireless systems for 5G / 6G wireless. [Diagram 2] FIG. 2 is a diagram of a conventional radio frequency (RF) signal generating device. [Diagram 3] FIG. 3 illustrates an embodiment of a wideband signal generator (WSG) in accordance with an embodiment of the disclosed technique. [Figure 4] Figure 4 shows an example of the arrangement of pipe sampling times. [Diagram 5] Figure 5 shows an example of bandpass filter bandwidth constraint. [Figure 6] FIG. 6 shows an embodiment of the input and output of the WSG algorithm. [Figure 7] FIG. 7 is a diagram for a first frequency range of the RF band. [Figure 8] FIG. 8 illustrates the second frequency range of the RF band. [Figure 9] FIG. 9 shows a diagram of the sample spectrum for the first frequency range. [Figure 10] FIG. 10 shows a diagram of the sample spectrum for the second frequency range. [Figure 11] FIG. 11 shows a screen shot of a simulated WSG showing the high RF frequency range. [Figure 12]FIG. 12 shows a simulated WSG two-tone screen with one tone having multiple tones in separate DAC pipes. [Figure 13] Figure 13 shows a screen shot of a simulated WSG with one tone at DC. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] FIG. 3 illustrates a wideband signal generator (WSG) 30 according to an embodiment of the disclosed technique. One or more processors (e.g., 36) generate samples according to an algorithm. A memory 34 may load samples created by a WSG algorithm to a DAC 32, or a processor 36 may load the samples to the memory 34 or directly to the DAC 32. The processor 36 may be one or more processors, including, among other things, a system processor, a specific field programmable gate array (FPGA), another DAC control processor, or a digital signal processor. As used herein, the use of the term "one or more processors configured to execute a program (code)" includes configuring an FPGA to generate samples. The memory 34 and / or processor 36 must be capable of generating digital samples according to an algorithm and sending them to a DAC.

[0011] The multiplexer 38 switches between two different DAC pipes and zero during the pattern as shown in Figure 3. The two DAC pipes can be two pipes from a single DAC or two separate DACs. The pipes have a delay and a sample period as shown in Figure 4. The output of the multiplexer is the following sequence of analog output signals: … DAC0, DAC1, 0, 0, 0,…, 0, DAC0, DAC1, 0, 0, 0,…, 0, DAC0, DAC1, 0, 0, 0,…

[0012] The specific implementation of the WSG is designed based on the RF range and instantaneous bandwidth (IBW) requirements. In the WSG, the DAC pipe delay and pipe sample rate are selected based on two criteria: 1. The inverse pipe delay of the DAC is at least twice the target RF range of the WSG. 2. The sample rate of the DAC pipe is greater than the target IBW of the WSG. For example, to get an RF range of 110 GHz and an IBW of 12.5 GHz, select a pipe delay of 4 picoseconds (ps) and a pipe sample rate of f s =15.625 giga-samples per second (GS / s). This configuration of the WSG satisfies both the conditions 1 / (4ps)=250GS / s>220GHz (2 x 110GHz) and 15.625GHz>12.5GHz. In this case, the sample period of the DAC pipe is 64ps, or 16 times 4ps.

[0013] The filters in FIG. 3 are generally constructed from band-pass (BP) filters and are selected based on the following criteria: 1. The bandwidth of the BP filter is larger than the target bandwidth of the WSG and smaller than the sample rate of the pipe. The passband of the BP filter [f1 pass ,f2 pass ] is the frequency band of interest [f1 interest ,f2 interest The frequency constraints are described in Equation 1 and shown in Figure 5. [Number 1] f1≦f1 stop <f1 pass ≦f1 interest <f2 interest ≦f2pass <f2 stop ≦f2=f1+f s In this example, the bandwidth of the BP filter is between the frequency of interest, 12.5 GHz, and the sample rate of the pipe, 15.625 GHz. According to various embodiments of the present disclosure, the BP filter may be fixed or tunable and may be configured in a filter bank. A low pass (LP) filter is treated as a special BP filter. The BP filter may be built into the test and measurement instrument or may be added as an external attachment connected to the output of the test and measurement instrument.

[0014] To generate the target RF signal, the WSG algorithm determines samples for two DAC pipes, as shown in Figure 6. The goal of the WSG algorithm is to calculate samples for the two DAC pipes so that when the resulting analog output signals from the two pipes are multiplexed with zeros and then filtered by the filter of Figure 3, the RF output signal matches the target RF signal. One or more processors use an algorithm, as described above, to generate digital samples to send to the DAC pipes, either directly or through memory. The digital samples are generated such that the RF output signal matches the target RF signal.

[0015] In Figure 6, f1 is the start frequency that satisfies the constraints of the BP filter defined in Equation 1. The WSG algorithm calculates the spectrum of the two DAC pipes. The digital samples of the DAC pipes can be obtained by IFFT on the spectrum calculated by the WSG algorithm.

[0016] Figure 3 and Equation 1 show f1 and f1+f s This shows that only frequency components within the frequency band between f1 and f1+f pass through the BP filter stage to the final RF output. The BP filter filters out other frequency components in the multiplexer output signal. The WSG algorithm uses thes It is only necessary to ensure that the spectrum of the frequency components in the frequency band between matches the spectrum of the target RF signal in that same frequency band.

[0017] In the WSG algorithm, there are two cases to consider. Figure 7 shows case 1, where the starting frequency f1 is 100% of the sample rate f s and the sample rate f s from the Nyquist frequency f Nyquist =f s It is between 0 and 2 minus 1 / 2. [Number 2] n f s -f Nyquist ≦f1 <n·f s n is an integer

[0018] Figure 8 shows case 2, where the starting frequency f1 is equal to the sample rate f s and multiples of f s Nyquist frequency f Nyquist It is between the above and the above. [Number 3] n f s ≦f1 <n·f s +f Nyquist n is an integer

[0019] In Case 1 and Case 2, the digital samples of DAC pipe 0 and pipe 1 determine the spectral content of the output RF signal. The spectral content of pipe 0 and pipe 1 determine the frequency content shown in Figures 7 and 8, which range from DC to f as shown in Figures 9 and 10, respectively. Nyquist It is between.

[0020] For case 1, nf in Fig. 7 s The spectra X2 and X3 around low It is generated from n f in Figure 7. s +f NyquistThe spectrum X0, X1 around the higher frequency X of DAC pipe 0 and pipe 1 in Figure 9. high is generated from

[0021] Using the following notation, it will be easier to understand how the spectrum of each pipe is determined. D: DAC pipe 0 to pipe 1 delay. P0: The spectrum of samples on DAC pipe 0 generated by the processor from the target spectrum. P0 low :f DC and n·f s The low frequency components of P0 between -f1 and X low This is the pipe 0 version of P0 high :n·f s -f1 and f Nyquist The high frequency components of P0 between X high This is the pipe 0 version of f low :P0 low The frequency of, which is a vector. f high :P0 high The frequency of, which is a vector. P1: The spectrum of the samples on DAC pipe 1 generated by the processor from the target spectrum. P1 low :f DC and n·f s The low frequency components of P1 between -f1 and X low This is the pipe 1 version of P1 high :n·f s -f1 and f Nyquist The high frequency components of P1 between X high This is the pipe 1 version of

[0022] In case 1, spectrum P0 in Fig. 10 low and P1 low The solution can be derived as follows:

number

[0023] P0 in Figure 10 high and P1 high The solution can be derived as follows:

number

[0024] Figures 11-13 show a numerical example, each a frame of an animated simulation of a two-tone signal swept from DC to 110 GHz, with the two tones spaced 12.5 GHz apart. For each frequency setting, the WSG algorithm finds the spectrum of DAC pipe 0 and pipe 1. The pipe delay D=4 ps and the sample rate of each DAC pipe f s =15.625GS / s. When the two tone signal is swept, both Case 1 and Case 2 are covered. This numerical example shows that an RF range from DC to 110GHz and an IBW of 12.5GHz is supported by the WSG.

[0025] Three frequency settings based on the frequency sweep are shown in Figures 11 to 13.

[0026] The spectra of the two DAC pipes are shown by the vertical dotted lines (e.g. 58). Nyquist In the left subplot, the amplitude spectrum is different and the phase is different for the two pipes in the screen shown in FIG. 11. The WSG algorithm generates digital samples and sends them to the two DAC pipes. Using the multiplexer 38 and filter 40 of FIG. 3, the spectrum of the generated signal matches the spectrum of the target signal.

[0027] Both the amplitude and phase spectra of the two DAC pipes are different for the frequency settings shown in Figure 12. The spectrum of the generated signal matches the spectrum of the target RF signal.

[0028] The frequency settings shown in FIG. 13 include DC.

[0029] In a conventional mixer-based RF signal generator system shown in Figure 2, the frequency of the mixing signal needs to be adjusted to cover various RF bands. In contrast, the multiplexer of the WSG shown in Figure 3 operates at a fixed rate and fixed multiplexer sequence. The WSG can be built with reduced complexity, cost, and power consumption, allowing one test and measurement instrument to support more RF channels. The WSG of this embodiment can be easily tuned to various frequency bands desired by users.

[0030] For 5G and 6G wireless testing, it is desirable to have more RF channels on a single signal generator. MIMO (Multiple-Input-Multiple-Output) is a key technology to enable 5G and 6G wireless systems. Multiple RF signals from a single signal generator can be better synchronized than multiple RF signals from multiple separate signal generators. More RF channels also improve test throughput.

[0031] One consideration when choosing between using two DAC pipes from one DAC or two DAC pipes from different DACs is that using two DAC pipes from one DAC may result in better matching between the pipes, which can lead to more accurate calibration and potentially better SFDR (spurious free dynamic range).

[0032] The embodiments of this application describe a WSG that can be used to test wideband high frequency RF applications such as 5G and 6G wireless. The WSG has a simplified structure that uses multiplexers instead of mixers. The algorithm of the WSG determines the signal for the DAC based on the configuration of the WSG and the target RF signal. The numerical example shows the accurate RF signal generation by the WSG. The WSG can operate in any target frequency band without adjusting the mixing signal.

[0033] Aspects of the disclosed technology can operate on specially created hardware, firmware, digital signal processors, or specially programmed general-purpose computers, including processors that operate according to programmed instructions. The term "controller" or "processor" in this application contemplates microprocessors, microcomputers, ASICs, and dedicated hardware controllers, among others. Aspects of the disclosed technology can be implemented in computer-available data and computer-executable instructions, such as one or more program modules, executed by one or more computers (including a monitoring module) or other devices. Generally, program modules include routines, programs, objects, components, data structures, and the like, which, when executed by a processor in a computer or other device, perform particular tasks or implement particular abstract data formats. The computer-executable instructions may be stored in computer-readable storage media, such as hard disks, optical disks, removable storage media, solid-state memory, RAM, and the like. As will be appreciated by those skilled in the art, the functionality of the program modules may be combined or distributed as desired in various embodiments. Furthermore, such functionality may be embodied in whole or in part in firmware or hardware equivalents, such as integrated circuits, field programmable gate arrays (FPGAs), etc. Certain data structures may be used to more effectively implement one or more aspects of the disclosed techniques, and such data structures are considered to be within the scope of the computer-executable instructions and computer-usable data described herein.

[0034] The disclosed aspects may, in some cases, be implemented in hardware, firmware, software, or any combination thereof. The disclosed aspects may also be implemented as instructions carried by or stored on one or more computer-readable media that may be read and executed by one or more processors. Such instructions may be referred to as computer program products. A computer-readable medium as described herein means any medium that can be accessed by a computing device. By way of example, and not limitation, computer-readable media may include computer storage media and communication media.

[0035] Computer storage media means any medium that can be used to store computer-readable information. By way of example and not limitation, computer storage media may include random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital video disc (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, and any other volatile or non-volatile removable or non-removable media implemented in any technology. Computer storage media excludes signals themselves and transitory forms of signal transmission.

[0036] A communication medium refers to any medium capable of communicating computer readable information. By way of example, and not limitation, communication media may include coaxial cables, fiber optic cables, air, or any other medium suitable for communicating electrical, optical, radio frequency (RF), infrared, acoustic, or other types of signals. Working Example

[0037] In the following, examples useful for understanding the technology disclosed in the present application are presented. The embodiment of the technology may include one or more of the examples described below and any combination thereof.

[0038] Example 1 is a wideband signal generating device comprising one or more digital-to-analog converters (DACs), each having one or more pipes and a sample rate; a multiplexer that receives analog output signals from at least two pipes of the one or more DACs and multiplexes the analog output signals with zeros to generate an output stream; a bandpass filter that receives the output stream and filters out frequency components in the output stream outside a target frequency band to generate a radio frequency (RF) output signal within the target frequency band; and one or more processors, the one or more processors being configured to execute a program that causes the one or more processors to perform a process of generating digital samples and a process of transferring the digital samples to the one or more DACs, the digital samples being generated to generate an analog output signal that matches the RF output signal to the target RF frequency band.

[0039] Example 2 is the wideband signal generating apparatus of example 1, in which the one or more DACs include one DAC, and the at least two pipes are from the one DAC.

[0040] Example 3 is a wideband signal generating device described in either Example 1 or Example 2, wherein the one or more DACs include at least two DACs, and the at least two pipes include at least one pipe for each of the at least two DACs.

[0041] Example 4 is the wideband signal generating device of any of Examples 1 to 3, wherein the one or more processors are configured to transfer the digital samples directly to the one or more DACs.

[0042] A fifth embodiment is the wideband signal generating device according to any one of the first to fourth embodiments, further comprising a memory.

[0043] Example 6 is a wideband signal generating device of Example 5, wherein the one or more processors are configured to transfer the digital samples to the memory, and the memory transfers the digital samples to the one or more DACs.

[0044] Example 7 is a wideband signal generating device of any of Examples 1 to 6, wherein the bandpass filter has a bandwidth wider than the target bandwidth of the RF output signal and narrower than the sample rate.

[0045] Example 8 is a wideband signal generating device of any of Examples 1 to 7, wherein the program that causes the one or more processors to perform a process of generating the digital samples causes the one or more processors to perform a process using a start frequency and a spectrum of the target frequency band.

[0046] Example 9 is a wideband signal generating device of Example 8, wherein the one or more processors are further configured to execute a program that causes the one or more processors to perform processing to set a pipe delay in the one or more DACs to be greater than or equal to twice a target RF frequency band and to set the sample rate to be greater than a target instantaneous bandwidth of the wideband signal generating device.

[0047] Example 10 is the wideband signal generating apparatus of example 8, wherein the start frequency is between a multiple of the sample rate and a multiple of the sample rate minus a Nyquist frequency.

[0048] Example 11 is the wideband signal generating apparatus of Example 8, wherein the start frequency is between the sample rate and a multiple of the sample rate plus the Nyquist frequency.

[0049] Example 12 is a method for generating a wideband signal, comprising: generating an analog output signal using at least two pipes of one or more DACs, each having one or more pipes and a sample rate; multiplexing the analog output signal from the at least two pipes with zeros to generate an output stream; filtering the output stream to remove frequency components outside a target frequency band in the output stream to generate a radio frequency (RF) output signal in the target frequency band; and generating digital samples such that the RF output signal matches the target RF frequency band.

[0050] Example 13 is the method of example 12, wherein filtering the output stream includes filtering the output stream using a bandpass filter having a bandwidth wider than a target bandwidth of the RF output signal and narrower than the sample rate.

[0051] Example 14 is the method of any of examples 12 or 13, wherein generating the digital samples includes determining a spectrum of the digital samples using a start frequency and a spectrum of the target frequency band.

[0052] Example 15 is the method of example 14, further comprising setting a pipe delay in the one or more DACs to greater than or equal to twice the target RF frequency band and setting a sample rate greater than a target instantaneous bandwidth of the wideband signal generator.

[0053] Example 16 is the method of example 14, wherein the start frequency is between a multiple of the sample rate and a multiple of the sample rate minus a Nyquist frequency.

[0054] Example 17 is the method of example 14, wherein the start frequency is between the sample rate and a multiple of the sample rate plus a Nyquist frequency.

[0055] Example 18 is the method of any one of examples 12 to 17, in which the process using at least two pipes includes a process using at least two pipes from one DAC.

[0056] Example 19 is the method according to any one of examples 12 to 17, in which the process using at least two pipes includes a process using one pipe from each of at least two DACs.

[0057] In addition, the present description refers to specific features. It should be understood that the disclosure herein includes all possible combinations of those specific features. When a specific feature is disclosed in connection with a particular aspect or embodiment, that feature can also be used in connection with other aspects and embodiments, to the extent possible.

[0058] Furthermore, when the application refers to a method having two or more defined steps or processes, those defined steps or processes may be performed in any order or simultaneously, unless the context precludes such a possibility.

[0059] All features disclosed in the specification, claims, abstract and drawings, and all steps in any disclosed method or process, may be combined in any combination, except where at least some of such features or steps are mutually exclusive combinations. Each feature disclosed in the specification, abstract, claims and drawings may be replaced by an alternative feature serving the same, equivalent or similar purpose, unless expressly stated otherwise.

[0060] For convenience of illustration, specific embodiments of the disclosed technology have been illustrated and described, but it will be understood that various modifications can be made therein without departing from the spirit and scope of the invention. Accordingly, the disclosed technology should not be limited, except as by the appended claims. [Explanation of symbols]

[0061] 30 Wideband Signal Generator (WSG) 32 DAC 34 Memory 36 processors 38 Multiplexer 40 Filters

Claims

1. A wideband signal generating device, comprising: one or more digital-to-analog converters (DACs), each having one or more pipes and sample rates; a multiplexer that receives analog output signals from at least two pipes of the one or more DACs and multiplexes the analog output signals and zeros into an output stream; a bandpass filter that receives the output stream and filters out frequency components in the output stream that are outside a target frequency band to generate a radio frequency (RF) output signal within the target frequency band; One or more processors Equipped with The one or more processors are configured to execute a program that causes the one or more processors to generate digital samples and transfer the digital samples to the one or more DACs, the digital samples being generated to generate an analog output signal that matches the RF output signal to a target RF frequency band.

2. 2. The wideband signal generating apparatus of claim 1, wherein the one or more DACs include a single DAC, and the at least two pipes are from the single DAC.

3. 2. The wideband signal generating apparatus of claim 1, wherein the one or more DACs include at least two DACs, and the at least two pipes include at least one pipe for each of the at least two DACs.

4. 2. The wideband signal generator of claim 1, wherein the bandpass filter has a bandwidth wider than the target bandwidth of the RF output signal and narrower than the sample rate.

5. 2. The wideband signal generator of claim 1, wherein the program causing the one or more processors to perform a process for generating the digital samples causes the one or more processors to perform a process using a start frequency and a spectrum of the target frequency band.

6. 6. The wideband signal generating device of claim 5, wherein the one or more processors are further configured to execute a program that causes the one or more processors to perform processing to set a pipe delay in the one or more DACs to more than twice a target RF frequency band and to set the sample rate to greater than a target instantaneous bandwidth of the wideband signal generating device.

7. 6. The wideband signal generating apparatus of claim 5, wherein said start frequency is between a multiple of said sample rate and a multiple of said sample rate minus the Nyquist frequency.

8. 1. A method for generating a wideband signal, comprising the steps of: generating an analog output signal using at least two pipes of one or more DACs each having one or more pipes and a sample rate; multiplexing said analog output signals from said at least two pipes with zeros to generate an output stream; filtering the output stream to remove frequency components in the output stream outside a target frequency band to generate a radio frequency (RF) output signal in the target frequency band; generating digital samples such that the RF output signal matches a target RF frequency band; A method for generating a wideband signal comprising:

9. 9. The method of claim 8, wherein filtering the output stream comprises filtering the output stream with a bandpass filter having a bandwidth wider than a target bandwidth of the RF output signal and narrower than the sample rate.

10. 9. The method of claim 8, wherein generating the digital samples comprises determining a spectrum of the digital samples using a start frequency and a spectrum of the target frequency band.

11. 11. The method of claim 10, further comprising: setting a pipe delay in the one or more DACs to greater than or equal to twice the target RF frequency band and setting a sample rate greater than a target instantaneous bandwidth of the wideband signal generator.

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