Balun transformer with improved harmonic suppression

Balance to unbalance conversion transformer with improved harmonic suppression

The present invention generally relates to an electronic assembly and a method of forming an electronic assembly, and more specifically to a balanced-to-unbalanced conversion transformer with improved harmonic suppression.

This application was filed in the United States under Patent Application No. 12/025,315 on February 4, 2008.

In recent years, wireless communication devices, such as mobile phones, continue to provide users with more and more functions, as well as improved performance and computing capabilities, while the overall size of their devices is also decreasing. An important component visible in these devices is a transformer called a "balanced-to-unbalanced conversion". Generally speaking, a balanced-to-unbalanced converter converts a single-ended or "unbalanced" signal that is usually received and transmitted by an antenna into a differential or "balanced" signal that is usually seen in the processing electronics of wireless communication devices.

Two important parameters in the design of a balanced-to-unbalanced converter are insertion loss and common-mode rejection, because they determine the value selection and layout of transformers and capacitors. Therefore, the design of a balanced-to-unbalanced converter often rarely considers other performance factors, such as harmonic suppression. However, good harmonic suppression is often very beneficial and important to the overall circuit performance.

In order to improve the effectiveness of harmonic suppression, a specific harmonic filter is often added to the balanced-to-unbalanced conversion circuit. However, these harmonic filters generally increase the insertion loss and the manufacturing cost of the system and increase the overall size required for the balanced-to-unbalanced converter.

Therefore, it is best to provide an electronic assembly that includes a balanced-to-unbalanced converter with improved harmonic performance while avoiding the use of conventional harmonic filters. In addition, other desirable features and characteristics of the present invention will become apparent from the following [Embodiments] and the scope of the attached patent application, as well as the combination of the accompanying drawings and the prior art field and prior art.

The following detailed description is actually only exemplary and is not intended to limit the present invention or the application and use of the present invention. In addition, it is not meant to be bound by any expressed or implied theory presented in the prior art, prior art, summary of the invention, or the following detailed description. It should also be noted that Figures 1 to 9 are merely illustrative and not drawn to scale.

The present invention will be described below in conjunction with the following drawings, in which the same numbers represent the same elements.

Figures 1 to 9 illustrate an electronic assembly. The electronic assembly includes: a substrate; a balanced-to-unbalanced conversion transformer, which is formed on the substrate and includes a first winding and a second winding, each of the first winding and the second winding has its own And a reaction circuit component formed on the substrate and electrically coupled between the first and second ends of the second winding.

In an embodiment, the midpoint of the second winding of the balanced-to-unbalanced conversion transformer is connected to ground via a reactive component (for example, an inductor, a capacitor, or a combination thereof), which makes the circuit in the balanced to unbalanced state. The second harmonic resonance of the fundamental frequency of the balun. The value of the added reactive components is such that when combined with the existing balanced-to-unbalanced converter, it generates a resonance in the output signal of the second harmonic frequency, thereby generating a notch. Therefore, the second harmonic suppression is significantly improved.

Figure 1 illustrates a transmitter system 20 according to an embodiment of the invention. The system 20 includes transmitter electronics (or transmitter) 22, a transformer circuit 24, a power amplifier 26, and an antenna 28. In one embodiment, the transmitter 22 is in the form of an integrated circuit formed on a semiconductor substrate, as generally understood, and includes a first port 30 and a second port 32 (ie, input and/or output) , As discussed in more detail. As shown in FIG. 1, the transformer circuit 24 includes a first "unbalanced" (or single-ended) port 34, a second "unbalanced" (or single-ended) port 36, and a first "balanced" (or differential) port. Port 38 and the second "balanced" (or differential) port 40. The antenna 28 is connected to the first unbalanced port 34 of the transformer circuit through the power amplifier 26, and the second unbalanced port 36 of the transformer circuit 24 is connected to ground (or a reference voltage). The first balance port 38 and the second balance port 40 of the transformer circuit 24 are respectively connected to the first port 30 and the second port 32 of the transmitter 22.

Figures 2 and 3 illustrate the transformer circuit 24 in more detail. Referring to FIG. 2, the transformer circuit further includes a balanced-to-unbalanced converter 42, a first tuning capacitor 44 and a second tuning capacitor 46, and a reaction (or resonance) circuit 48. The balun 42 includes a first winding (or coil) 50 and a second winding (or coil) 52 on the respective first side 54 and second side 56 of the transformer circuit 24. Those familiar with the art will understand that the first side 54 of the transformer circuit 24 (or the balanced-to-unbalanced converter 42) is "unbalanced" and the second side 56 is "balanced". The first tuning capacitor 44 is connected across the opposite end (not shown) of the first winding 50 and is between the first unbalanced port 34 and the second unbalanced port 36, and the second tuning capacitor 46 is horizontally connected. The opposite end of the second winding 52 is connected between the first balance port 38 and the second balance port 40.

The reaction circuit 48 includes a resonant capacitor 58 and a resonant inductor 60 (ie, two reaction circuit components), which are connected in series to the second winding 52 of the balun 42 and a reference terminal ( Or reference voltage) 62 between. The reaction circuit 48 is connected to the second winding 52, connected between the ends of the second winding 52, and more specifically connected to a midpoint (for example, a central point of the second winding 52). Connector) 64. The electrical values (ie, capacitance and inductance) of the resonant capacitor 58 and the resonant inductor 60 are selectively selected so that the balance-to-unbalance converter 42, the tuning capacitors 44 and 46, and the reaction circuit 48 together form a Harmonic suppression is balanced to unbalanced conversion transformer, as described in more detail below. The harmonic suppression balanced to unbalanced conversion transformer has a fundamental frequency, such as 2.450 gigahertz (GHz).

As shown in FIG. 3, the transformer circuit 24 is formed on a substrate 66, such as a semiconductor substrate mainly made of silicon (Si), germanium (Ge), gallium arsenide (GaAs) or a combination thereof. The substrate 66 may be, for example, a semiconductor wafer having a diameter of approximately 150, 200, or 300 millimeters (mm) and divided into a plurality of dies or "dice". The substrate 66 is used in conjunction with complementary metal oxide semiconductor (CMOS), integrated passive device manufacturing processes, or other semiconductor manufacturing processes to form the circuit 24 on a wafer. The substrate 66 defines a circuit plane on which etching, deposition or other techniques are used to form the transformer circuit 24 in one or more layers.

The first winding 50 and the second winding 52 are composed of, for example, aluminum (Al), copper (Cu), gold (Au) or any actual combination thereof (for example, AlCu) and use, for example, heat or electron beam evaporation, physical gas Conductive traces formed by phase deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD) or electroplating. The tuning capacitors 44 and 46 and the resonant capacitor 58 (FIG. 2) may be metal-insulator-metal (MIM) capacitors, as generally understood, and included on the opposite side of an insulator (for example, made of silicon nitride) Of two conductive plates.

FIG. 4 is an enlarged view of the substrate 66. As shown in the figure, various electronic components can be formed on the substrate 66, such as a thin film (TF) resistor 68, an inductor 70, and a MIM capacitor 72. Those skilled in the art will understand that the TF resistor 68 and the inductor 70 can be at least partially formed during the same processing steps used to form the transformer circuit 24 shown in FIGS. 1-3. Although not specifically shown, a plurality of components formed on the substrate 66 can be coupled such that a harmonic filter, a coupler, a switch, and an additional transformer are formed thereby. The electronic components shown in FIG. 3 combined with the transformer circuit 24 of FIG. 2 can form a microelectronic or electronic assembly or integrated passive device (IPD) 74. The IPD 74 can be a discrete component with no other electronic devices formed on the substrate 66. Alternatively, the transmitter 22 may be formed on the substrate 66 together with the IPD 74.

After the final processing steps, the final processing steps may include forming contact formations (for example, solder balls) and interconnecting electronic components and conductors (for example, wire bonding) of the contact formations, and the substrate 66 may be sawed into A single microelectronic die block (or IPD or semiconductor wafer), which is packaged and installed in various electronic or computing systems. FIG. 5 schematically illustrates an exemplary power amplifier (PA) module 76 in which the IPD 74 can be utilized. In the depicted embodiment, the PA module 76 includes a power amplifier (or power integrated circuit) 78, a decoupling circuit 80, a matching/tuning circuit 82, a harmonic filter 84, a duplexer 86, and a control circuit 88.

Although not described in detail, the power amplifier can be a "small" power integrated circuit, as generally understood, and can include a power circuit component configured to manage power and a power circuit component configured to control, regulate, monitor, At least one additional component that affects or reacts to the operation of the power circuit. In fact, the power circuit component may include a power transistor, and the at least one additional component may include, but is not limited to: a sensor (for example, an environmental condition sensor, an electromagnetic sensor, an organic inductance sensor) , An electrical property sensor, a converter or the like); a power control component; an analog component; a digital logic component or any combination thereof.

During operation, referring to FIGS. 1 and 2, a differential or "balanced" signal is generated by the transmitter electronics 22 and sent to the circuit 24 via the first balance port 38 and the second balance port 40. Since the differential signal passes through the balanced side 56 of the circuit 24, in particular the balanced to the second winding 52 of the unbalanced converter 42, where the first and second windings 50 of the balanced to unbalanced converter 42 Inductive coupling occurs between and 52, so that the signal is converted into a single-ended or "unbalanced" signal on the unbalanced side 54 of the circuit 24, as generally understood. The single-ended signal is sent through the first unbalanced port 34 of the transformer circuit 24 and amplified by the amplifier 26 before being sent to the antenna 28.

Figure 6 graphically illustrates the insertion loss (IL) of an experimental embodiment with a capacitor and an inductor in the reaction circuit. As shown, the transformer circuit (or harmonic suppression balanced to unbalanced conversion transformer) operates at a fundamental frequency of 2.450 GHz, as shown at the peak 90, and the second harmonic at the fundamental frequency of 4.900 GHz is in the insertion loss A notch 92 appears. The insertion loss is -0.537 decibels (dB) at the fundamental frequency and -19.441 dB at the second harmonic.

FIG. 7 illustrates a transformer circuit 94 according to another embodiment of the present invention. The transformer circuit 94 may include many components similar to the components of the transformer circuit 24 shown in FIG. 2. However, a reaction circuit 96 in the transformer circuit 94 shown in FIG. 7 includes a resonant capacitor 98 and two resonant inductors 100. FIG. 8 graphically illustrates the insertion loss of an experimental embodiment similar to that shown in FIG. 7. Similar to the embodiment of FIG. 6, the transformer circuit of FIG. 7 operates at a fundamental frequency of 2.450 GHz, as shown at the peak 102, and a notch 104 appears at the second harmonic of the fundamental frequency of 4.900 GHz. The insertion loss is -0.585 decibels (dB) at the fundamental frequency and -18.447 dB at the second harmonic. It should also be noted that a second notch 106 (that is, caused by the second inductor) appears at about 3.100 GHz, but does not affect the operation of the circuit at the fundamental frequency. Figure 9 illustrates the common mode rejection ratio (CMRR) of the transformer circuit of Figures 7 and 8. As shown in the peak 108, the CMRR of the transformer circuit is 27.754dB, so it will not be adversely affected by the reaction circuit.

One advantage of the above electronic assembly is that the reactive components in the reaction circuit make the balanced-to-unbalanced converter transformer resonate at the second harmonic (or other selected harmonics) of its fundamental frequency. Therefore, the second harmonic suppression performance and the overall performance of the device are significantly improved. Another advantage is that the reactive components of the reaction circuit can be formed using conventional semiconductor processing steps and can therefore be integrated with other components of the device. Therefore, the impact on the overall size and manufacturing cost of the device is greatly reduced.

It should also be understood that the reaction circuit can also be used with a receiver and transceiver system similar to the transmitter system shown in FIG. 1, except that the transmitter is replaced by a receiver or a transceiver. In an embodiment using a receiver, a single-ended or "unbalanced" signal is received by an antenna and amplified by an amplifier before passing through an unbalanced port of the transformer circuit. Since the single-ended signal passes through the unbalanced side of the circuit, inductive coupling occurs between the first winding and the second winding of the balanced-to-unbalanced converter, so that the signal is converted into a difference on the balanced side of the circuit Dynamic or "balanced" signals are generally understood in this technology. The differential signal is sent to the transmitter through the balance ports of the transformer circuit.

Other embodiments may include reactive components in the reaction circuit, the reactive components containing selected electrical values such that the harmonics suppress harmonics that occur outside the second harmonic, such as the third harmonic or the fourth harmonic . The reaction circuit can be formed with only a single capacitor or inductor. For example, a single inductor may take the form of a wire bond that is long enough to have a suitable inductance for the desired electrical effect. As will be appreciated, other processes can be used to form the various components described above. As mentioned above, active electronic components (such as transistors) and other integrated circuit components can be formed on the silicon substrate together with passive electronic components.

Provide an electronic assembly. The electronic assembly includes: a substrate; a balanced-to-unbalanced conversion transformer, which is formed on the substrate and includes a first winding and a second winding, each of the first winding and the second winding has its own And a reaction circuit component formed on the substrate and electrically coupled between the first and second ends of the second winding. The balanced-to-unbalanced conversion transformer and the reaction circuit component can jointly form a harmonic suppression balanced-to-unbalanced conversion transformer with a fundamental frequency. The reaction circuit component can be tuned so that the harmonic suppression is balanced to a selected harmonic resonance of the balun transformer at the fundamental frequency.

The selected harmonic frequency may be the second harmonic of the fundamental frequency. The reaction circuit component may include a capacitor. The reaction circuit assembly may be electrically coupled to the midpoint of the second winding.

The electronic assembly may further include an antenna electrically coupled to the first end of the first winding of the balanced-to-unbalanced conversion transformer. The electronic assembly may further include a ground terminal electrically coupled to the second end of the first winding of the balun transformer.

The second winding of the balanced-to-unbalanced conversion transformer may include a center tap, and the reaction circuit component is electrically coupled to the second winding through the center tap. The electronic assembly may also include an amplifier electrically coupled to the first winding of the balanced-to-unbalanced conversion transformer. The reaction circuit component may also include an inductor. The substrate may include silicon, germanium, gallium arsenide, or a combination thereof.

Provide an electronic assembly. The electronic assembly includes: a substrate; a balanced-to-unbalanced conversion transformer, which is formed on the substrate and includes a first winding and a second winding, each of the first winding and the second winding has its own An antenna formed on the substrate and electrically coupled to the first end of the first winding of the balun transformer; a ground terminal on the substrate and Is electrically coupled to the second end of the first winding of the balun transformer; an amplifier is electrically coupled to the first end of the first winding of the balun transformer; and a reaction A circuit component is formed on the substrate and is electrically coupled between the first end and the second end of the second winding. The balanced-to-unbalanced conversion transformer and the reaction circuit component jointly form a harmonic suppression balanced-to-unbalanced conversion transformer with a fundamental frequency. The reaction circuit component is tuned so that the harmonic suppression balance-to-unbalanced converter transformer resonates at a selected harmonic of the fundamental frequency.

The reaction circuit component may include a capacitor. The selected harmonic may be the second harmonic of the fundamental frequency.

The electronic assembly may also include a transmitter on the substrate and electrically coupled to the first end and the second end of the second winding of the balun transformer. The second winding of the balanced-to-unbalanced conversion transformer may include a center tap and the reaction circuit component is electrically coupled to the second winding through the center tap. The electronic assembly may also include a second ground terminal electrically coupled to the reaction circuit assembly.

Another method of forming an electronic assembly is provided. A first winding is formed on a substrate. The first winding has a first end and a second end. A second winding is formed on the substrate. The second winding has a first end and a second end. The first winding and the second winding together form a balanced-to-unbalanced conversion transformer. A reaction circuit component is formed on the substrate. The reaction circuit assembly is electrically coupled between the first end and the second end of the second winding. The reaction circuit component is tuned so that the balanced-to-unbalanced conversion transformer and the reaction circuit component jointly form a harmonic suppression balance-to-unbalanced conversion transformer with a fundamental frequency and resonate at a selected harmonic of the frequency.

The reaction circuit component may include a capacitor. The selected harmonic frequency may be the second harmonic of the fundamental frequency. The method may also include forming an antenna on the substrate. The antenna may be electrically coupled to the first end of the first winding. The second winding may include a center tap and the reaction circuit component is electrically coupled to the second winding through the center tap.

Although at least one exemplary embodiment has been presented in the above detailed description of the present invention, it should be understood that many variations are possible. It should also be understood that the exemplary embodiment or the exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the present invention in any way. To be precise, the above detailed description will provide convenient instructions for those skilled in the art to implement the exemplary embodiments of the present invention. It should be understood that the present invention is set forth in the appended claims and their legal equivalents without departing from Various changes can be made to the function and configuration of the elements described in an exemplary embodiment within the scope.

<p>20. . . Launcher system</p><p>twenty two. . . Transmitter electronics</p><p>twenty four. . . Transformer circuit</p><p>26. . . Power amplifier</p><p>28. . . antenna</p><p>30. . . First port</p><p>32. . . Second port</p><p>34. . . The first "unbalanced" port</p><p>36. . . The second "unbalanced" port</p><p>38. . . The first "balanced" port</p><p>40. . . The second "balanced" port</p><p>42. . . Balanced to unbalanced converter</p><p>44. . . First tuning capacitor</p><p>46. . . Second tuning capacitor</p><p>48. . . Reaction circuit</p><p>50. . . First winding</p><p>52. . . Second winding</p><p>54. . . First side</p><p>56. . . Second side</p><p>58. . . Resonant capacitor</p><p>60. . . Resonant inductor</p><p>62. . . Reference terminal</p><p>64. . . midpoint</p><p>66. . . Substrate</p><p>68. . . Thin film resistors</p><p>70. . . Inductor</p><p>72. . . Metal-insulator-metal capacitors</p><p>74. . . Integrated passive device</p><p>76. . . Power amplifier module</p><p>78. . . Power amplifier</p><p>80. . . Decoupling circuit</p><p>82. . . Matching/tuning circuit</p><p>84. . . Harmonic filter</p><p>86. . . Diplexer</p><p>88. . . Control circuit</p><p>90. . . crest</p><p>92. . . Notch</p><p>94. . . Transformer circuit</p><p>96. . . Reaction circuit</p><p>98. . . Resonant capacitor</p><p>100. . . Resonant inductor</p><p>102. . . crest</p><p>104. . . Notch</p><p>106. . . Second notch</p><p>108. . . crest</p>

Fig. 1 is a schematic block diagram of a transmitter system according to an embodiment of the present invention;

Fig. 2 is a schematic diagram of a transformer circuit in the transmitter system of Fig. 1;

Fig. 3 is a plan view of a substrate on which the transformer circuit of Fig. 2 is formed;

Figure 4 is a cross-sectional side view of an integrated passive device (IPD);

FIG. 5 is a schematic diagram of a power amplifier (PA) module, in which the IPD of FIG. 4 can be used;

6 is a graph comparing the operating frequency and insertion loss of an embodiment of the present invention similar to FIG. 2;

Fig. 7 is a schematic diagram of a transformer circuit according to another embodiment of the present invention;

FIG. 8 is a graph comparing the operating frequency and insertion loss of an embodiment of the present invention similar to FIG. 7; and

FIG. 9 is a graph comparing the operating frequency and the common mode rejection ratio of an embodiment of the present invention similar to FIG. 7.