SYSTEM AND METHOD FOR MEASURING THE RADIO FREQUENCY PHASE SHIFT OF AN INLINE DEVICE

Abstract

A test apparatus includes an oscillator circuit with an inline device. The oscillator circuit contains a loop with a variable-gain amplifier and a variable-feedback block. The inline device is installed between the variable-gain amplifier and the variable-feedback block. An output from the variable-feedback block is fed into the variable-gain amplifier. A processor varies the phase of the variable-feedback block to locate a block phase shift at which the oscillator circuit produces an output signal. From this block phase shift, the processor determines a device phase shift of the inline device and sets up the operation of a driven circuit powered by the output of the oscillator circuit using the device phase shift of the inline device.

Description

[0001] The present disclosure relates to inline devices and in particular to a system and a method for measuring the phase shift for an inline device and for compensating for the phase shift introduced by the inline device.

[0002] Various electronic devices, such as beam shaping devices, require precise phase relationships to operate correctly. Repeated device installation, temperature changes, varying mechanical conditions, and other factors can introduce additional phase shifts into the signal path, all of which must be accounted for to maintain the desired phase relationship. Therefore, it is desirable to provide a system and method for measuring and compensating for phase shifts resulting from the insertion of an inline device.

[0003] US 4,988,957 A discloses an electronically controlled oscillator in the RF / microwave range that uses a stacked quartz filter in the feedback path as the frequency-determining element and adjusts the phase by means of a controllable impedance so that the Barkhausen conditions are met. In one embodiment, an overmodulated quartz filter with comb-filter characteristics is used, with an additional delay quartz filter enabling an adjustable phase delay to tune the oscillator to different resonances. US 2012 / 0308227 A1 describes a digital coherent receiver that uses a sampling phase detector to detect the phase of a sampled digital signal and adjusts it accordingly via a phase adjuster.

[0004] Several filters with different equalization, sensitivity-monitoring phase detectors, correction coefficient generators and an adder are used to generate a corrected and stable phase signal.

[0005] It is an object of the invention to provide an improved method for determining a phase shift of an inline device as well as an improved oscillator circuit.

[0006] This problem is solved by the method according to claim 1 and the oscillator circuit according to claim 4.

[0007] The invention relates to a method for determining the phase shift of an inline device. The inline device is installed in an oscillator circuit containing a loop with a variable-gain amplifier and a variable-feedback block. The inline device is installed between the variable-gain amplifier and the variable-feedback block. An output from the variable-feedback block is fed into the variable-gain amplifier. The phase of the variable-feedback block is varied to locate the block phase shift at which the oscillator circuit generates an output signal. From the block phase shift, the device phase shift of the inline device is determined.Using the inline device's phase shift, the operation of a driven device powered by the oscillator circuit's output is set. Furthermore, localizing the block phase shift involves varying the phase of the variable-feedback block and amplifying the amplifier until the loop satisfies a Barkhausen phase condition. The method further includes determining a first block phase shift of the variable-feedback block that satisfies the Barkhausen phase condition without the inline device, inserting the inline device into the loop, determining a second block phase shift that satisfies the Barkhausen phase condition for the loop with the inline device, and determining the inline device's phase shift from the difference between the first and second block phase shifts.

[0008] In addition to one or more of the features described herein, and if the variable feedback block includes an adjustable phase shifter, the method further includes varying the phase of the adjustable phase shifter to locate the block phase shift.

[0009] In addition to one or more of the features described here, the adjustable phase shifter is a mechanically adjustable phase shifter, an electrically adjustable phase shifter, a variable capacitance diode (varicap diode), or a time delay device.

[0010] In addition to one or more of the features described herein, the method further includes increasing the gain of the variable-gain amplifier to operate the oscillator circuit to generate a square wave in a saturated state, and adjusting the phase of the variable-feedback block to determine the block phase shift with the oscillator circuit in the saturated state.

[0011] In addition to one or more of the features described herein, the method further includes the use of the output of the oscillator circuit in a beamforming circuit and / or a radar circuit and / or a mobile communications network.

[0012] Another aspect of the invention relates to an oscillator circuit. The oscillator circuit includes a variable-gain amplifier, a variable-feedback block, an inline device, and a processor. The inline device is installed between the variable-gain amplifier and the variable-feedback block to form a loop. An output from the variable-feedback block is fed into the variable-gain amplifier.The processor is configured to vary the phase of the variable feedback block to locate a block phase shift at which the oscillator circuit generates an output signal, to determine a device phase shift of the inline device from the block phase shift, and to use the device phase shift of the inline device to set the operation of a driven circuit powered by the output of the oscillator circuit. Furthermore, the processor is configured to locate the block phase shift by varying the phase of the variable feedback block until the loop satisfies a Barkhausen phase condition.Furthermore, the processor is configured to determine a first block phase shift of the variable feedback block that satisfies the Barkhausen phase condition without the inline device, a second block phase shift that satisfies the Barkhausen phase condition for the loop with the inline device inserted into the loop, and the device phase shift of the inline device from a difference between the first block phase shift and the second block phase shift.

[0013] In addition to one or more of the features described herein, and wherein the variable feedback block includes an adjustable phase shifter, the processor is further configured to localize the block phase shift by varying the phase of the adjustable phase shifter.

[0014] In addition to one or more of the features described here, the adjustable phase shifter is a mechanically adjustable phase shifter, an electrically adjustable phase shifter, a variable capacitance diode (varicap diode), or a time delay device.

[0015] In addition to one or more of the features described here, the processor is further configured to increase the gain of the variable-gain amplifier to operate the oscillator circuit to generate a square wave in a saturated state, and to localize the block phase shift with the oscillator circuit in the saturated state by adjusting the phase of the variable-feedback block.

[0016] In addition to one or more of the features described here, the output is sent to a beamforming circuit and / or a radar circuit and / or a mobile network.

[0017] According to a further exemplary embodiment, a test device is disclosed. The test device comprises an oscillator circuit and a processor. The oscillator circuit includes a variable-gain amplifier and a variable-feedback block, wherein an inline device can be installed between the variable-gain amplifier and the variable-feedback block to form a loop, and an output from the variable-feedback block is fed into the variable-gain amplifier.The processor is configured to vary a phase of the variable feedback block to locate a block phase shift of the variable feedback block at which the oscillator circuit produces an output signal, to determine a device phase shift of the inline device from the block phase shift, and to use the device phase shift of the inline device to set an operation of a driven circuit that is operated by the output of the oscillator circuit.

[0018] In addition to one or more of the features described here, the processor is further configured to locate the block phase shift by varying the phase of the block with variable feedback until the loop satisfies a Barkhausen phase condition.

[0019] In addition to one or more of the features described herein, the processor is further configured to determine a first block phase shift of the variable feedback block satisfying the Barkhausen phase condition without the inline device, a second block phase shift satisfying the Barkhausen phase condition for the loop with the inline device inserted into the loop, and the device phase shift of the inline device from a difference between the first block phase shift and the second block phase shift.

[0020] In addition to one or more of the features described herein, and wherein the variable feedback block includes an adjustable phase shifter, the processor is further configured to vary the phase of the adjustable phase shifter to localize the block phase shift.

[0021] In addition to one or more of the features described here, the adjustable phase shifter is a mechanically adjustable phase shifter, an electrically adjustable phase shifter, a variable capacitance diode (varicap diode), or a time delay device.

[0022] In addition to one or more of the features described here, the processor is further configured to increase the gain of the variable-gain amplifier to operate the oscillator circuit to generate a square wave in a saturated state, and to localize the block phase shift with the oscillator circuit in the saturated state by adjusting the phase of the variable-feedback block.

[0023] The features and advantages described above, and further features and advantages of the disclosure, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0024] Further features, advantages and details appear only as examples in the following detailed description, which refers to the drawings; they show: Fig. 1 an electrical circuit in accordance with an exemplary embodiment; Fig. 2 a representation of the oscillator circuit in an alternative embodiment; Fig. 3 a modified oscillator circuit in an illustrative embodiment; Fig. 4. a gain-phase space for a loop; and Fig. 5. A flowchart of a procedure for searching in the amplification phase space by examining only the phase parameters.

[0025] The following description is merely exemplary and is not intended to limit the present disclosure, its application, or uses. It should be noted that in the course of the drawings, corresponding reference numerals denote similar or corresponding sections and features.

[0026] Fig. Figure 1 shows an electrical circuit 100 according to an exemplary embodiment. The electrical circuit 100 comprises an oscillator circuit 102 and a driven device or driven circuit 104. An output from the oscillator circuit 102 is provided to the driven circuit 104. The driven circuit 104 can be a beamforming circuit, a radar circuit, a mobile communication network, or any other suitable electrical device that can be operated with an input of an oscillator signal.

[0027] The oscillator circuit 102 contains an amplifier 106 (e.g., an operational amplifier) ​​and a feedback network 108. The amplifier 106 is designated A and the feedback network 108 is designated B. The output of the amplifier 106 is fed into the input of the feedback network 108, and the output of the feedback network is fed into the input of the amplifier.

[0028] For oscillation to occur, a feedback circuit must satisfy the Barkhausen conditions at a specific frequency. The Barkhausen conditions include that 1) the overall gain of the loop is uniform and 2) the overall phase shift of the loop is a multiple of 360 degrees (2π). The first Barkhausen condition (the Barkhausen gain condition) is shown in Eq. (1): |A|*|B|=1 where |A| is the magnitude of the amplifier gain and |B| is the magnitude of the feedback network gain. The second condition according to Barkhausen (Barkhausen phase condition) is shown in Eq. (2): ang(A)+ang(B)=k*2π where ang(A) is the phase of the amplifier, ang(B) is the phase of the feedback network, and k is an integer. In general, the gain of the amplifier |A| is a constant value, and the phase shift of the amplifier ang(A) is a constant value. Similarly, the gain of the feedback network |B| is a constant value, and the phase shift of the feedback network ang(B) is a constant value.

[0029] Fig. Figure 2 shows a representation 200 of the oscillator circuit 102 in an alternative embodiment. The oscillator circuit 102 comprises the amplifier 106, the feedback network 108, and an inline device 202. The inline device 202 can be a wire, a filter, a transmission line, or another suitable device. The output of the amplifier 106 is fed into the inline device 202. The output of the inline device 202 is fed into the feedback network 108, and the output of the feedback network is fed into the input of the amplifier 106.

[0030] The inclusion of the inline device 202 in the loop changes both the gain and the phase of the loop. The conditions according to Barkhausen are valid for the oscillator circuit 102. Fig. 2 shown in Eqs. (3) and (4): |A|*|B|*|C|=1 where |C| is the magnitude of the inline device. ang(A)+ang(B)+ang(C)=k*2π where ang(C) is the phase of the inline device. By balancing the change in gain and phase caused by inserting the inline device 202 into the loop, it is possible to determine the additional device phase shift introduced by the inline device.

[0031] Fig. Figure 3 shows an adapted oscillator circuit 300 in an illustrative embodiment. The adapted oscillator circuit 300 can be used as part of a test apparatus for testing a device phase shift introduced by an inline device. The adapted oscillator circuit 300 includes a variable-gain amplifier 302 and a variable-feedback block 304. The variable-feedback block 304 is designated B' and includes the feedback network 108, the inline device 202, and an adjustable phase shifter 306.

[0032] A controller 308 controls the operation of the variable-gain amplifier 302 and the adjustable phase shifter 306. The controller 308 may include a processing circuit arrangement that may contain an application-specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or a group) with memory executing one or more software or firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functionality. The controller 308 may include a non-transient, computer-readable medium that stores instructions which, when processed by one or more processors of the controller 308, implement a method for determining a device phase shift of the inline device 202 according to one or more embodiments described in detail herein.

[0033] The gain |A| of the variable-gain amplifier 302 can be increased or decreased. Both the gain and the phase shift of the adjustable phase shifter 306 can be adjusted. As a non-limiting set of examples, the adjustable phase shifter 306 can be a mechanically adjustable phase shifter, an electrically adjustable phase shifter (e.g., a mechanical phase shifter adjusted by an electric motor), a variable-capacitance diode (varicap diode), a device based on one or more varicap diodes, a time-delay device, or a device with multiple time-delay sections, etc. According to one embodiment, the output of the inline device 202 is fed into the adjustable phase shifter 306. The feedback network 108 and the adjustable phase shifter 306 are connected in series.

[0034] Since the device phase shift of the inline device 202 is most likely not zero (i.e., ang(C) ≠ 0), the adjustable phase shifter 306 can be operated such that the loop of Fig. 3 satisfies the Barkhausen phase condition. Once a block phase shift (ang(B')) for the variable feedback block 304 (and the gain of the variable amplifier 302) is found that satisfies the Barkhausen phase condition, namely ang(A) + ang(B') = k*2π, it is possible to extract ang(C) (i.e., the device phase shift introduced by the inline device 202). This is shown in Eq. (4): ang(C)=ang(B')−ang(B)

[0035] To determine the conditions according to Barkhausen, the gain and phase of the loop must be adjusted until the conditions are met. This corresponds to searching in the gain-phase space of the loop circuit.

[0036] The phase shift of the inline device can be determined using separate measurements. A first block phase shift of the variable feedback block is determined that satisfies the Barkhausen phase condition when the inline device 202 is not in the loop. The inline device 202 is then inserted into the loop. A second block phase shift of the variable feedback block is determined that satisfies the Barkhausen phase condition for the loop containing the inline device 202. The gain of the variable feedback block can be adjusted before determining the second phase shift. The phase shift of the inline device 202 is determined from the difference between the first and second block phase shifts.

[0037] Fig. Figure 4 shows a gain-phase space 400 for a loop. A gain axis (G) and a phase axis (ϕ) are shown. An amplitude axis (A) indicates the strength of the oscillation signals and / or whether the oscillations decrease or increase abruptly. The space in which the gain and phase satisfy the Barkhausen conditions is defined as a first region 402. Where the gain and phase do not satisfy the Barkhausen conditions, a second region 404 is defined. In the modified oscillator circuit 300, oscillations are present when the loop satisfies both Barkhausen conditions, but generally not present when either of these conditions is not met. A sharp boundary 406 lies between the first region 402 and the second region 404.When searching in the amplification phase space, oscillations therefore appear quickly (as shown by the extension of the boundary along the amplitude axis) when the conditions according to Barkhausen are met (i.e. in the first region 402) and disappear quickly when the conditions are not met (i.e. in the second region 404).

[0038] The adjustable phase shifter 306 generally exhibits an insertion loss, which results in a gain relationship between the input signal and the output signal. This insertion loss can be measured and stored independently. When the adjustable phase shifter 306 is added to the loop, the stored data can be retrieved and used as an output value when searching for the loop's gain.

[0039] The insertion loss of the inline device 202 is generally unknown. Therefore, when the inline device 202 is introduced into the loop, a search algorithm can be executed to determine a value of the gain |A| of the variable-gain amplifier 302 that compensates for the insertion loss of the inline device 202 such that the loop satisfies the Barkhausen gain condition.

[0040] Although a two-dimensional search in the amplification phase space can be performed to locate the conditions according to Barkhausen, due to the sharpness of the boundary 406 between the first region 402 and the second region 404, such a two-dimensional search can be a time-consuming process. It is therefore desirable to search in the amplification phase space in a way that can be completed in a shorter time.

[0041] Fig.Figure 5 shows a flowchart 500 of a method for searching in gain-phase space, in which only the phase parameters are searched. In block 502, the inline device is inserted into the oscillator circuit, which contains a variable-gain amplifier 302 and an adjustable phase shifter 306. In block 504, the gain of the variable-gain amplifier 302 is increased to a value that saturates the oscillator circuit. In this saturated state, the variable-gain amplifier 302 generates square waves instead of sine waves. Since the square wave contains several harmonic frequencies (more than just a fundamental frequency), the search can only be performed by varying the phase parameter. In block 506, a one-dimensional search of the phase parameter can be performed to locate a phase that satisfies the Barkhausen condition for the loop.Compared to a two-dimensional search in gain-phase space, this one-dimensional search can be performed in a shorter time. In block 508, the gain of the adjustable phase shifter is determined, which ensures that the loop satisfies the Barkhausen gain condition for the localized phase.

[0042] The terms "a" and "an" do not denote a limit on the number of elements, but rather indicate the presence of at least one of the referenced element. The term "or" means "and / or" unless clearly indicated otherwise by context. A reference to "an aspect" in the application text means that a specific element (e.g., a feature, a structure, a step, or a property) described in connection with that aspect is contained in at least one aspect described therein and may or may not be present in other aspects. It should also be understood that the described elements in the various aspects may be combined in any suitable manner.

[0043] When an element, such as a layer, a thin layer, an area, or a substrate, is described as "attached" to another element, it may be located directly adjacent to that element, or there may be intervening elements. Conversely, when an element is described as "directly adjacent" to another element, there are no intervening elements.

[0044] Unless otherwise specified herein, all testing standards shall be the most recent valid standard as of the filing date of this application or, if priority is claimed, as of the filing date of the earliest priority application in which the testing standard appears.

[0045] Unless otherwise defined, technical and scientific terms used herein have the same meaning as would normally be understood by a person skilled in the field to which this disclosure belongs.

[0046] While the disclosure described above has been described with reference to exemplary embodiments, those skilled in the art will understand that various modifications can be made and elements can be replaced by their equivalents without altering its scope. Furthermore, many adaptations can be made to fit a particular situation or material to the instructions given in the disclosure without deviating from its essential scope. Therefore, it is intended that the present disclosure is not limited to the specific embodiments disclosed, but includes all embodiments that fall within its scope.

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