Patent Application
20090201115
Inductors and transformers are useful components in electronic circuits. Inductors are useful for construction of passive filters, voltage-controlled oscillators (VCOs), matching networks, transformers, and the like.
Transformers are devices that transfer electrical energy from one circuit to another through inductively coupled electrical conductors. A changing current in a primary circuit creates a changing magnetic field that induces a changing voltage in a secondary circuit. A load applied to the secondary circuit creates current flow in the transformer, thereby transferring energy between circuits.
According to an embodiment of an electronic circuit in an integrated circuit package comprises an inductance element. The inductance element further comprises a plurality of separated metal strips formed on a substrate and a ferrite core coupled to the substrate. The metal strip plurality is formed between the substrate and the ferrite core. The inductance element further comprises a plurality of wires coupled to the separated metal strips whereby the metal strips and wires form a continuous coil. The ferrite core is interposed between the metal strip plurality and the wire plurality.
Embodiments of the invention relating to both structure and method of operation may best be understood by referring to the following description and accompanying drawings:
Referring to
The wires 110 can be bond wires that connect around the ferrite core 108 from the separated metal strips 104 formed on the substrate. In an example implementation, the bond wires 110 can be connected to the metal strips 104 using a semiconductor device auto-bonding process.
An insulating material (not shown) is formed around the ferrite core 108. For example, the ferrite core 108 can be wrapped in an insulating tape or other insulating material.
Fundamental elements of the electronic circuit 100 include the ferrite core 108 which is located in the package. The package has metallization below the ferrite core 108 which forms the metal strips 104. In an example configuration, for a coil 112 that includes four turns around the ferrite 108 the metallization can include five metal strips 104 below the ferrite 108. A typical cross-section of the inductance element 102 can include metallization, insulation, ferrite 108, then additional insulation above the ferrite 108. Then bond wire 110 can be used to connect diagonally from one strip 104 across the ferrite 108 to conductively contact an adjacent metal strip.
In some applications and embodiments, the inductance element 102 can be configured to operate as an inductor.
The separated metal strips 104 can be arranged as mutually parallel-aligned strips with the wires 110 coupled diagonally across the ferrite core 108 so that the metal strips 104 and wires 110 form a continuous coil 112.
Any suitable type of ferrite core 108 can be used for the inductance element 102. Some embodiments, for example as shown in
Referring to
In an example application, a power-switching transformer can be completely integrated in a single package with power output at a sink.
As depicted in
Referring to
The bond wires 110 connect around the ferrite core 108 from the separated metal strips 104 formed on the substrate 106 and can be connected to the metal strips 104 using a semiconductor device auto-bonding process.
Referring to
In an example implementation, an integrated circuit 100 can include an Ethernet physical layer (PHY) 132 and the inductance element 102 can function as a digital isolator 130 for the Ethernet PHY 132 whereby the Ethernet PHY 132 is split across the digital isolator 130.
The inductance element 102 can be implemented to attain several aspects of functionality. For example, the inductance element 102 can be used in an Ethernet interface that includes digital isolation. The Ethernet PHY can be split across the digital isolator. Implementations of the inductance element 102 can also be used to construct a transformerless PHY.
In various embodiments and applications, the number of turns of a coil 112 can be selected according to desired functionality. For example, a coil 112 can be constructed with four turns, five turns, or N turns. The size of the metal strips 104 and wires 110 can also be selected according to implementation or application. Typical sizes of the metal strips 104 are 2 millimeters or 4 millimeters in length, although any suitable length can be implemented. For example, a configuration of metal strips of 4 millimeters (mm) in length coupled by bond wires 110 can form a coil 112 on one side of a ferrite toroid 108 and a similar coil 112 can be formed on a second side of the ferrite toroid 108, for example to form a transformer 126 which can be coupled to the PHY 132.
The inductance element can be formed using a ferrite bar, however electromagnetic interference (EMI) can leak from the ends of the bar. Thus, a ferrite toroid can be used, which reduces EMI because the toroid is closed, avoiding EMI leakage.
For a configuration in which each turn of the bond wire 110 has an inductance of approximately 1-2 nanoHenry (nH). With addition of the toroid, inductance is substantially increased. For a configuration with inductance of 1-2 μH per turn and a coil with 5 or 6 turns, then a total inductance of 20 to 50 μH can be attained.
Referring to
The auto-former 136 configuration can be implemented for Ethernet applications for accessing a power-over-Ethernet PoE signal with digital isolation. The auto-former 136 includes transformer across the winding with a center tap that is accessed to pull power. The illustrative structures and associated manufacturing techniques enable the auto-former 136 to be constructed inside a package.
Referring to
The inductor 102 is shown in usage with the DC-DC converter 138 so that the inductor which is conventionally coupled outside an integrated circuit package can be moved inside the chip.
The integrated circuit 100 can comprise a an integrated circuit 146 coupled to the substrate 106, a power output terminal 148 of the integrated circuit package, and the inductance element 102 coupled between the integrated circuit 146 and the power output terminal 148 as a power inductor filter 150.
A further application of the illustrative inductance element structures is a filter for the inductor. Power supplies have inductors on the front end that connect to the power supply to ensure better supply fidelity. The illustrative structures and techniques enable front-end filtering on the power supply inside the package.
Referring to
The inductance element application including on the choke 140 can be used for various purposes such as electromagnetic interference (EM I) suppression. The choke 140 can be used in EMI circuits including a differential design and a shunt design wherein EMI is shunted to ground, for example at half an ohm. The illustrative structure can be used to form a common mode choke that is steering. The steering common mode choke 140 can be constructed inside an integrated circuit package in addition to a shunt, enabling formation of both a choke and shunt.
In various embodiments, for example as shown in
In various embodiments, for example as shown in
As shown in
Referring to
Referring to
The bond wires can be coupled 210 to the separated metal strips using a semiconductor device auto-bonding process.
Referring to
Referring to
Terms “substantially”, “essentially”, or “approximately”, that may be used herein, relate to an industry-accepted tolerance to the corresponding term. Such an industry-accepted tolerance ranges from less than one percent to twenty percent and corresponds to, but is not limited to, component values, integrated circuit process variations, temperature variations, rise and fall times, and/or thermal noise. The term “coupled”, as may be used herein, includes direct coupling and indirect coupling via another component, element, circuit, or module where, for indirect coupling, the intervening component, element, circuit, or module does not modify the information of a signal but may adjust its current level, voltage level, and/or power level. Inferred coupling, for example where one element is coupled to another element by inference, includes direct and indirect coupling between two elements in the same manner as “coupled”.
While the present disclosure describes various embodiments, these embodiments are to be understood as illustrative and do not limit the claim scope. Many variations, modifications, additions and improvements of the described embodiments are possible. For example, those having ordinary skill in the art will readily implement the steps necessary to provide the structures and methods disclosed herein, and will understand that the process parameters, materials, and dimensions are given by way of example only. The parameters, materials, and dimensions can be varied to achieve the desired structure as well as modifications, which are within the scope of the claims. Variations and modifications of the embodiments disclosed herein may also be made while remaining within the scope of the following claims. For example, various aspects or portions of a network interface are described including several optional implementations for particular portions. Any suitable combination or permutation of the disclosed designs may be implemented.
