Comb signal generator and method of providing a phase and amplitude reference

Abstract

A comb signal generator that includes at least two signal sources that each provide a signal, wherein the signals provided by the at least two signal sources are shaped similarly. The com signal generator also has a combining circuit connected with the at least two signal sources, wherein the combining circuit is configured to combine the signals provided by the at least two signal sources, thereby generating a combined signal. Further, the com signal generator includes a clipping circuit connected with the combining circuit, wherein the clipping circuit is configured to receive and process the combined signal, thereby generating a comb signal. Further, a method of providing a phase and amplitude reference is described.

Claims

1. A comb signal generator, comprising: at least two signal sources that each provide a signal, wherein the signals provided by the at least two signal sources are shaped similarly; a combining circuit connected with the at least two signal sources, wherein the combining circuit is configured to combine the signals provided by the at least two signal sources, thereby generating a combined signal; and a clipping circuit connected with the combining circuit, wherein the clipping circuit is configured to receive and process the combined signal, thereby removing certain portions of the combined signal forwarded to the clipping circuit and generating a comb signal that has several discrete frequency lines.

2. The comb signal generator according to claim 1, further comprising an output that is configured to output an output signal.

3. The comb signal generator according to claim 2, wherein the output signal corresponds to the comb signal generated by the clipping circuit or wherein the output signal is derived from the comb signal generated by the clipping circuit.

4. The comb signal generator according to claim 1, wherein the signals provided by the at least two signal sources are sinusoidal signals.

5. The comb signal generator according to claim 1, wherein the combined signal generated by the combining circuit is a two-tone signal.

6. The comb signal generator according to claim 1, wherein the combining circuit is configured to combine the signals provided by the at least two signal sources linearly.

7. The comb signal generator according to claim 1, wherein the combining circuit is a passive combining circuit and/or wherein the combining circuit comprises at least one of a passive adder and a passive combiner.

8. The comb signal generator according to claim 1, wherein the comb signal generator comprises more than two signal sources that are connected with the combining circuit.

9. The comb signal generator according to claim 1, wherein the at least two signal sources, the combining circuit and the clipping circuit together establish a module.

10. The comb signal generator according to claim 9, wherein the comb signal generator comprises at least two modules that are connected with each other via a combiner that is connected with the respective clipping circuits of the modules.

11. The comb signal generator according to claim 1, wherein the comb signal generator comprises a third signal source that provides a third signal, wherein the third signal source and the clipping circuit both are connected to a combiner that is configured to combine the third signal and the comb signal generated by the clipping circuit, thereby generating a further combined signal.

12. The comb signal generator according to claim 11, wherein the comb signal generator comprises a clipper that is connected with the combiner, and wherein the clipper is configured to receive and process the further combined signal, thereby generating a further comb signal.

13. The comb signal generator according to claim 1, wherein the at least two signal sources are independent of each other and/or free-running oscillators.

14. The comb signal generator according to claim 1, wherein at least one of the at least two signal sources is a frequency-locked or phase-locked signal source.

15. The comb signal generator according to claim 1, wherein at least one of the at least two signal sources is derived from a common reference source.

16. The comb signal generator according to claim 1, wherein the clipping circuit is established by a single diode, a network of diodes or a linearized circuit.

17. A method of providing a phase and amplitude reference for a device to be calibrated, the method comprising: generating, by using a first signal source, a first signal with a first frequency; generating, by using a second signal source, a second signal with a second frequency that is different from the first frequency; feeding the first signal and the second signal into a combining circuit; combining the first signal and the second signal passively, thereby generating a combined signal that is a two-tone signal; and feeding a clipping circuit with the two-tone signal, which processes the two-tone signal, wherein the respective amplitudes of the two tones are such that the clipping circuit is forced to clip as much as possible of respective signal components, thereby shaping the combined signal during signal processing by the clipping circuit while removing certain portions of the combined signal forwarded to the clipping circuit and generating a comb signal.

18. A comb signal generator, comprising: at least two signal sources that each provide a signal, wherein the signals provided by the at least two signal sources are shaped similarly, wherein the signals provided by the at least two signal sources are sinusoidal signals that have different frequencies; a combining circuit connected with the at least two signal sources, wherein the combining circuit is configured to combine the signals provided by the at least two signal sources, thereby generating a combined multiple tone signal; and a clipping circuit connected with the combining circuit, wherein the clipping circuit is configured to receive and process the combined multiple tone signal, wherein the clipping circuit is configured to shape the respective waveform of the combined multiple tone signal while altering the spectral components of the combined multiple tone signal, thereby generating a comb signal.

Description

DESCRIPTION OF THE DRAWINGS

(1) The foregoing aspects and many of the attendant advantages of the claimed subject matter will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

(2) FIG. 1 schematically shows an overview of a comb signal generator according to a first embodiment of the present disclosure;

(3) FIG. 2 schematically shows an overview of a comb signal generator according to a second embodiment of the present disclosure;

(4) FIG. 3 schematically shows an overview of a comb signal generator according to a third embodiment of the present disclosure;

(5) FIG. 4 schematically shows an overview of a comb signal generator according to a fourth embodiment of the present disclosure;

(6) FIG. 5 shows an overview illustrating the combined signal;

(7) FIG. 6 shows an overview illustrating the comb signal; and

(8) FIG. 7 shows an overview illustrating information concerning the spectral lines of the comb signal.

DETAILED DESCRIPTION

(9) The detailed description set forth below in connection with the appended drawings, where like numerals reference like elements, is intended as a description of various embodiments of the disclosed subject matter and is not intended to represent the only embodiments. Each embodiment described in this disclosure is provided merely as an example or illustration and should not be construed as preferred or advantageous over other embodiments. The illustrative examples provided herein are not intended to be exhaustive or to limit the claimed subject matter to the precise forms disclosed.

(10) FIG. 1 shows a comb signal generator 10 that comprises a housing 12 in which components of the comb signal generator 10 are encompassed. In the shown embodiment, the comb signal generator 10 comprises two signal sources 14 that each provide a signal, wherein the signals provided by the signal sources 14 are shaped similarly.

(11) In some embodiments, both signal sources 14 output or rather provide a sinusoidal signal wherein the sinusoidal signals provided by the signal sources 14 have different frequencies as illustrated by the respective diagrams associated with the signal sources 14.

(12) The signal sources 14 are connected with a combining circuit 16 that may also be called a summing junction, as the combining circuit 16 receives the signals provided by the signal sources 14, namely the sinusoidal signals having different frequencies. The combining circuit 16 is configured to combine the signals received from the signal sources 14, thereby generating a combined signal that relates to a two-tone signal as illustrated by the respective diagram associated with the combining circuit 16.

(13) Generally, the combining circuit 16 or rather the summing junction may be established, for example, by a power splitter, a power combiner, etc. However, there are many ways to realize the combining circuit 16 or rather the summing junction. The respective selection depends on the frequency range of use as well as the sensitivity of the signal sources 14 to frequency/load-pulling. For instance, a resistive combiner may be used or even a Wilkinson combiner. In some embodiments, the resistive combiner has a wide bandwidth, but no isolation, whereas the Wilkinson combiner has excellent isolation, but a lower bandwidth compared to the resistive combiner.

(14) In some embodiments, the combining circuit 16 is configured to combine the signals provided by the signal sources 14 linearly, thereby generating the two-tone signal. A more detailed overview regarding the combined signal, namely the two-tone signal, is shown in FIG. 5. In FIG. 5, the combined signal is shown in time domain and in frequency domain.

(15) In some embodiments, the combining circuit 16 is a passive combining circuit, as it comprises a passive adder and/or a passive combiner, thereby establishing the summing junction that sums the individual sinusoidal signals provided the signal sources 14 in order to generate the combined signal.

(16) The comb signal generator 10 also comprises a clipping circuit 18 that is connected with the combining circuit 16 such that the clipping circuit 18 receives the combined signal from the combining circuit 16. The clipping circuit 18 is configured to process the combined signal, thereby generating a comb signal that has several discrete frequency lines or rather spectral lines as illustrated in the respective diagram that is associated with the clipping circuit 18. A more detailed overview regarding the comb signal, e.g., its spectral lines, is shown in FIG. 6. In FIG. 6, the comb signal is shown in time domain and in frequency domain.

(17) Further information regarding the spectral lines is provided by the overview shown in FIG. 7, wherein information regarding the amplitude and the phase of the spectral lines is illustrated.

(18) In the shown embodiment, the clipping circuit 18 is directly connected with an output 20 of the comb signal generator 10 that is located in an outer surface of the housing 12. Via the output 20, an output signal is outputted, wherein the output signal corresponds to the comb signal generated by the clipping circuit 18 in the shown embodiment.

(19) In some embodiments, the signal sources 14, the combining circuit 16 as well as the clipping circuit 18 together establish a module 22, which may be provided in an integrative and modular manner Therefore, the comb signal generator 10 may be extended by encompassing more than one module 22.

(20) A representative embodiment is shown in FIG. 2, as the comb signal generator 10 comprises two modules 22 that are connected with each other via a combiner 24. The combiner 24 is directly connected with the respective clipping circuit 18 of the modules 22 such that the comb signal provided by the respective clipping circuit 18 are combined by the combiner 24 appropriately thereby generating a further combined signal that corresponds to the output signal of the comb signal generator 10, as the combiner 24 is directly connected with the output 20 of the comb signal generator 10.

(21) The embodiment shown in FIG. 2 is also called corporate variant, as it comprises two modules 22, each having two signal sources 14, one combining circuit 16 and one clipping circuit 18, wherein the modules 22 are connected with each other by the combiner 24, for example a passive combiner such as a passive adder.

(22) In FIG. 3, another embodiment of the comb signal generator 10 is shown that substantially corresponds to the one shown in FIG. 1.

(23) In some embodiments, the comb signal generator 10 comprises three signal sources 14 that are connected with the combining circuit 16 such that the combining circuit 16 processes three different signals, namely three sinusoidal signals having different frequencies, in order to generate a three-tone signal that corresponds to the combined signal. The three-tone signal is forwarded to the clipping circuit 18 for being processed by the clipping circuit 18 appropriately.

(24) In some embodiments, the three signal sources 14, the combining circuit 16 as well as the clipping circuit 18 together may establish the module 22.

(25) In some embodiments, the comb signal generator 10 shown in FIG. 3 is also called N-way variant, as it comprises n=3 signal sources 14 that provide n=3 signals. In FIG. 4, a further embodiment of the comb signal generator 10 is shown that is based on the embodiment shown in FIG. 1. In some embodiments, the embodiment shown in FIG. 4 also comprises the module 22, wherein the comb signal generator 10 additionally comprises a third signal source 26 that provides a third signal.

(26) In contrast to the embodiment shown in FIG. 3, the third signal source 26 is connected with a combiner 28 that is also connected with the clipping circuit 18 of the module 22.

(27) Thus, both the clipping circuit 18 and the third signal source 26 are connected with the combiner 28 that is configured to combine the third signal provided by the third signal source 26 and the comb signal generated by the clipping circuit 18. The combiner 28 generates a further combined signal based on the comb signal and the third signal received.

(28) The comb signal generator 10 according to the fourth embodiment further comprises a clipper 30, such as clipper circuitry, that is connected with the combiner 28 such that the clipper 30 receives and processes the further combined signal generated by the clipper 30. The clipper 30 processes the further combined signal, thereby generating a further comb signal that has the respective characteristics of a comb signal, namely the several spectral lines.

(29) In any case, it is ensured that the comb signal generator 10 outputs an output signal that substantially corresponds to a comb signal having several discrete frequencies with a well-known amplitude and phase relationship.

(30) Therefore, the respective output signal outputted by the comb signal generator 10 can be used for accurate and precise calibration of a device to be calibrated, e.g. a receiver.

(31) Moreover, the embodiments shown are based on a passive combination of the signals provided by the signal sources 14. Therefore, the combining circuit 16 relates to a passive combining circuit that passively combines the signals received, e.g., without any active control.

(32) The combined signal generated by the combining circuit 16 undergoes the clipping while being processed by the clipping circuit 18 such that a comb signal is obtained that is used for calibrating the device to be calibrated.

(33) In a certain embodiment, a 5G measurement device that typically operates over several 100 MHz at 40 GHz shall be calibrated. According to the prior art, a comb generator with a 10 MHz reference may be used that has to generate the 4.000.sup.th harmonic with an extremely low signal-to-noise ratio (SNR) that is not usable anymore. Alternatively, it was known in the state of the art to use a 4 GHz reference, for instance. Thus, the 10.sup.th harmonic would already be sufficient for calibrating the 5G measurement device. However, the frequency grid, also called raster, is significantly larger, namely step size of 4 GHz, compared to the previous prior art solution. In some embodiments, the frequency grid or rather the step size is larger than the frequency band of interest. Hence, interpolation calculations are required which are time-consuming and which require respective computational resources.

(34) In contrast to the prior art, the comb signal generator 10 according to embodiments of the present disclosure may make use of the two signal sources 14 that provide tones of 39.995 GHz and 40.005 GHz, respectively. Thus, a 10 MHz spacing around 40 GHz can be obtained.

(35) Thus, the signal-to-noise ratio (SNR) is improved compared to the first known solution in the prior art mentioned above, while simultaneously providing a small frequency grid compared to the second known solution in the prior art mentioned above.

(36) Hence, the signal levels at the output 20, for example the signal levels of the comb signal generated by the clipping circuit 18, are at their highest level in that frequency range, e.g., several 10s of dBs higher than the ones provided by the comb generator mentioned above. Further, the amplitudes of those tones have a precise level (as well as phase), enabling to perform a real vector calibration.

(37) Moreover, a narrower frequency grid as well as a more accurate reference signal, e.g. the output signal, can be created by the comb signal generator 10, for example for any given frequency of interest.

(38) In summary, the comb signal generator 10 provides a precise phase and amplitude reference with high signal levels at high frequencies, thereby ensuring a faster and more accurate calibration. Additionally, a fine frequency grid or rather frequency resolution is obtained such that post-processing and interpolation techniques can be reduced or rather minimized, for example avoided completely.

(39) Certain embodiments disclosed herein, for example the respective module(s), utilize circuitry (e.g., one or more circuits) in order to implement standards, protocols, methodologies or technologies disclosed herein, operably couple two or more components, generate information, process information, analyze information, generate signals, encode/decode signals, convert signals, transmit and/or receive signals, control other devices, etc. Circuitry of any type can be used. It will be appreciated that the term “information” can be use synonymously with the term “signals” in this paragraph. It will be further appreciated that the terms “circuitry,” “circuit,” “one or more circuits,” etc., can be used synonymously herein.

(40) In an embodiment, circuitry includes, among other things, one or more computing devices such as a processor (e.g., a microprocessor), a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a system on a chip (SoC), or the like, or any combinations thereof, and can include discrete digital or analog circuit elements or electronics, or combinations thereof. In an embodiment, circuitry includes hardware circuit implementations (e.g., implementations in analog circuitry, implementations in digital circuitry, and the like, and combinations thereof).

(41) In an embodiment, circuitry includes combinations of circuits and computer program products having software or firmware instructions stored on one or more computer readable memories that work together to cause a device to perform one or more protocols, methodologies or technologies described herein. In an embodiment, circuitry includes circuits, such as, for example, microprocessors or portions of microprocessor, that require software, firmware, and the like for operation. In an embodiment, circuitry includes one or more processors or portions thereof and accompanying software, firmware, hardware, and the like.

(42) The present application may reference quantities and numbers. Unless specifically stated, such quantities and numbers are not to be considered restrictive, but exemplary of the possible quantities or numbers associated with the present application. Also in this regard, the present application may use the term “plurality” to reference a quantity or number. In this regard, the term “plurality” is meant to be any number that is more than one, for example, two, three, four, five, etc. The terms “about”, “approximately”, “near” etc., mean plus or minus 5% of the stated value. For the purposes of the present disclosure, the phrase “at least one of A and B” is equivalent to “A and/or B” or vice versa, namely “A” alone, “B” alone or “A and B.”. Similarly, the phrase “at least one of A, B, and C,” for example, means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C), including all further possible permutations when greater than three elements are listed.

(43) The principles, representative embodiments, and modes of operation of the present disclosure have been described in the foregoing description. However, aspects of the present disclosure which are intended to be protected are not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. It will be appreciated that variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present disclosure. Accordingly, it is expressly intended that all such variations, changes, and equivalents fall within the spirit and scope of the present disclosure, as claimed.