Patent Application
20220399870
The embodiments described herein relate generally to radio frequency (RF) interconnects, and more particularly, to frequency equalization and temperature compensation in RF devices.
RF devices are used for many applications, such as remote communication and sensing. The performance of such devices, for example, the ability of such devices to produce a desired output signal for a given input signal, may be affected by many different factors, such as a frequency of the input signal and a temperature of the RF device. For example, attenuation of RF signals generally increases as the frequency of the RF signal is increased. Further, as temperature increases, the attenuation of the RF signal generally increases correspondingly. Because RF devices are generally required to perform relatively consistently over a specified frequency range and/or temperature range, these interactions may be undesirable. However, the addition of compensation circuitry may increase costs of parts, manufacturing, and installation of the RF device, and once installed, may take up additional physical space within the RF application. A circuit that provides improved frequency equalization and temperature compensation is therefore desirable.
In one aspect, a frequency equalizer is provided. The frequency equalizer includes a coupler including a main segment extending between a first port and a second port and a coupled segment disposed in a coupling relationship with the main segment and extending between a third port and a fourth port. The frequency equalizer further includes a first thermistor electrically coupled in series between the first port and an input line, a second thermistor electrically coupled in series between the second port and an output line, and a first shunt resistor coupled across the third port. The frequency equalizer simultaneously provides frequency equalization and temperature compensation for signals transmitted through the frequency equalizer.
In another aspect, an electronics package for a frequency equalizer is provided. The electronics package includes a substrate having a first surface and a second surface, a ground plane disposed on the second surface, and a coupler including a main segment defined by a main strip disposed on the first surface and by the ground plane. The main segment extends between a first port and a second port. The coupler further includes a coupled segment defined by a coupled strip disposed on the second surface and by the ground plane. The coupled segment is disposed in a coupling relationship with the main segment and extends between a third port and a fourth port. The electronics package further includes a first thermistor disposed on the first surface and electrically coupled in series between the first port and an input line, a second thermistor disposed on the first surface and electrically coupled in series between the second port and an output line, and a first shunt resistor disposed on the first surface and electrically coupled across the third port. The electronics package simultaneously provides frequency equalization and temperature compensation for signals transmitted through the electronics package.
In another aspect, a method of manufacturing a frequency equalizer is provided. The method includes forming a coupler including a main segment extending between a first port and a second port and a coupled segment disposed in a coupling relationship with the main segment and extending between a third port and a fourth port, electrically coupling a first thermistor in series between the first port and an input line, electrically coupling a second thermistor in series between the second port and an output line, and electrically coupling a first shunt resistor across the third port. The frequency equalizer simultaneously provides frequency equalization and temperature compensation for signals transmitted through the frequency equalizer.
In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings.
The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.
Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.
The systems and methods described herein facilitate combined frequency equalization and temperature compensation for radio frequency (RF) applications using a single frequency equalizer circuit. The frequency equalizer circuit utilizes a combination of couplers and thermistors to perform both frequency equalization and temperature compensation. Accordingly, the frequency equalizer, as described herein, enables improved frequency equalization and temperature compensation in an RF application, and reduces the amount of material and physical space needed to perform frequency equalization and temperature compensation.
The subject matter described herein includes a frequency equalizer. The frequency equalizer includes a coupler that includes a main segment extending between a first port and a second port and a coupled segment disposed in a coupling relationship with the main segment and extending between a third port and a fourth port. The frequency equalizer further includes a first thermistor electrically coupled in series between the first port and an input line; a second thermistor electrically coupled in series between the second port and an output line, and a first shunt resistor coupled across the third port. The frequency equalizer simultaneously provides frequency equalization and temperature compensation for signals transmitted through the frequency equalizer.
In some implementations, the frequency equalizer further includes a second shunt resistor coupled across the fourth port.
In some implementations, the main segment and the coupled segment have different widths.
In some implementations, the coupler further includes a second coupled segment disposed in a second coupling relationship with the main segment and extending between a fifth port and a sixth port, and the frequency equalizer further includes a third shunt resistor and electrically coupled across the fifth port and a fourth shunt resistor and electrically coupled across the sixth port.
In some implementations, the coupler further includes a shunt line extending between the main segment and the coupled segment.
In some implementations, a length of the main segment is greater than a quarter wavelength of an input signal for the frequency equalizer.
In some implementations, the frequency equalizer further includes a first inductor electrically coupled in parallel with the first thermistor and a second inductor electrically coupled in parallel with the second thermistor.
In some implementations, at least one of the first thermistor and the second thermistor includes a thermistor paste.
In some implementations, the frequency equalizer further includes at least one impedance tuning structure electrically coupled across at least one of the input line, the output line, the first port, and the second port.
Referring now to
Coupler 102 includes a main segment 116 and a coupled segment 118. Main segment 116 is a transmission line segment extending between a first port 120 and a second port 122. Coupled segment 118 is a transmission line segment extending between a third port 124 and a fourth port 126. In some embodiments, main segment 116 and coupled segment 118 are implemented as microstrip, stripline, and/or another type of RF transmission line. Third port 124 is terminated with first shunt resistor 108, and fourth port 126 is terminated with second shunt resistor 110. In some embodiments, first shunt resistor 108 and second shunt resistor 110 have a resistance selected to be a matched impedance load for coupled segment 118. For example, in some embodiments, first shunt resistor 108 and second shunt resistor 110 each have a resistance of 50 ohms.
Coupled segment 118 is disposed in a coupling relationship with main segment 116. When RF power is received at first port 120, power is transmitted via second port 122 and fourth port 126. The amount of power transmitted at one of second port 122 and fourth port 126 depends on the frequency of the RF power received at first port 120. For example, when the input signal has a frequency (sometimes referred to herein as a “center frequency”) that corresponds to main segment 116 being one quarter wavelength, a maximum amount of RF power may be transferred to coupled segment 118 and transmitted via fourth port 126, and a minimum amount of power may be transmitted via second port 122. As the frequency of the input signal is increased above the center frequency, the amount of RF power transmitted via second port 122 increases. Accordingly, if coupler 102 is operated in a range greater than the center frequency, coupler 102 acts as an attenuator where the attenuation is inversely proportional to input frequency, and coupled segment 118 compensates for the tendency of RF signals to experience greater attenuation at increasingly higher frequencies.
In some embodiments, main segment 116 and coupled segment 118 have certain transmission line characteristics (e.g., characteristic impedance, electrical length, distance between transmission lines, etc.) selected to achieve a particular relationship between frequency and attenuation. For example, in some embodiments, main segment 116 and coupled segment 118 are microstrip lines each having a different width and/or shape that is selected to achieve a particular coupling relationship.
First thermistor 104 is electrically coupled between first port 120 of coupler 102 and an input 128, and second thermistor 106 is electrically coupled between second port 122 of coupler 102 and an output 130. In some embodiments, input 128 and output 130 are, for example, an input transmission line and an output transmission line, wherein frequency equalizer 100 receives an input signal at input 128 and transmits an output signal at output 130. First thermistor 104 and second thermistor 106 have a resistance that changes in response to a change in temperature of respective first thermistor 104 or second thermistor 106. For example, in some embodiments, first thermistor 104 and second thermistor 106 are negative temperature coefficient (NTC) thermistors that have a resistance that decreases as temperature increases. Accordingly, the attenuation of the input signal by first thermistor 104 and second thermistor 106 decreases as temperature increases, such that frequency equalizer 100 compensates for the tendency of RF signals to experience greater attenuation at increasing temperatures.
First inductor 112 is electrically coupled in parallel with first thermistor 104, and second inductor 114 is electrically coupled in parallel with second thermistor 106. First inductor 112 and second inductor 114 have each have an inductance that, at a predetermined operating frequency, tunes out a parasitic capacitance at first thermistor 104 and second thermistor 106, respectively.
Electronics package 200 includes conductive traces (e.g., microstrip) that, together with the ground plane, define, for example, main segment 116, coupled segment 118, first thermistor 104, second thermistor 106, first shunt resistor 108, second shunt resistor 110, first inductor 112, and second inductor 114. In some embodiments, at least one of first thermistor 104, second thermistor 106, first shunt resistor 108, and second shunt resistor 110 include a paste (e.g., a thermistor paste) disposed on substrate 202. Additionally or alternatively, in some embodiments, at least one of first thermistor 104, second thermistor 106, first shunt resistor 108, and second shunt resistor 110 include other types of resistive components (e.g., surface mount technology (SMT) components).
Impedance tuning structures 204 are coupled across input 128, output 130, first port 120, and second port 122. Impedance tuning structures 204 include microstrip disposed on the front surface of substrate 202 and a through hole 206 extending between and forming an electrical connection between the microstrip and the ground plane disposed on the back surface of substrate 202. In some embodiments, impedance tuning structures 204 have, for example, a length that is selected to tune out a parasitic capacitance in electronics package 200 at the predetermined operating frequency.
Second coupled segment 302 extends between a fifth port 308 and a sixth port 310. Fifth port 308 is terminated with third shunt resistor 304, and sixth port 310 is terminated with fourth shunt resistor 306. Third shunt resistor 304 and fourth shunt resistor 306 are matched impedance loads for second coupled segment 302. For example, in some embodiments, third shunt resistor 304 and fourth shunt resistor 306 each have a resistance of 50 ohms.
Second coupled segment 302 is disposed in a coupling relationship with main segment 116. Second coupled segment 302 generally functions as described with respect to coupled segment 118 (shown in
First shunt line 402 is a microstrip line extending between first port 120 and fourth port 126, and second shunt line 404 is a microstrip line extending between first port 120 and sixth port 310. First shunt line 402 and second shunt line 404 further increase coupling (e.g., a transfer of RF power away from main segment 116). Accordingly, electronics package 400 has an enhanced ability to achieve a particular desired relationship between frequency and attenuation.
Exemplary embodiments of methods and systems are described above in detail. The methods and systems are not limited to the specific embodiments described herein, but rather, components of systems and/or steps of the methods may be used independently and separately from other components and/or steps described herein. Accordingly, the exemplary embodiment can be implemented and used in connection with many other applications not specifically described herein.
Technical effects of the systems and methods described herein include at least one of (a) providing frequency equalization for attenuation in an RF device using a coupler having a length greater than one quarter wavelength of the input signal; (b) providing temperature compensation for attenuation in an RF device using one or more thermistors; and (c) reducing an amount of physical space of a frequency equalization and temperature compensation circuit by integrating frequency equalization and temperature compensation into a single electronics package.
Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the disclosure, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.
This written description uses examples to disclose various embodiments, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
This application claims priority to U.S. Provisional Patent Application No. 62/936,720 filed on Nov. 18, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety as part of the present application.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2020/060842 | 11/17/2020 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 62936720 | Nov 2019 | US |
