Patent Application
20130089199
Not applicable.
The disclosed subject matter relates generally to communication systems and, more particularly, to a communication system-in-package (SIP) formed on a metal microstructure.
Voice communication systems, such as central offices, private branch exchanges (PBXs), residential gateways, and Voice over IP (VOIP) adapters generally incorporate electronic circuits to form what is commonly known as a foreign exchange subscriber (FXS). FXS circuits provide BORSCHT functions, standing for Battery feed, Over-voltage support, integrated Ringing, line Supervision, Codec, Hybrid (2W/4W), and Testing.
In the 1970's and 1980's, FXS circuits included discrete components, large transformers and/or coils, and some simple integrated circuits that made up fairly large line cards. With advances in technology, integrated circuits (ICs) were developed to provide much of these functions. These ICs typically include a high-voltage Subscriber Line Integrated Circuit (SLIC) and a mixed signal Subscriber Line Audio Controller (SLAC).
Some communication companies have combined the high-voltage (SLIC) and mixed-signal (SLAC) dies into a single multi-chip module (MCM) device. One example device is the Zarlink Le88111. Subscriber line circuits require a high-voltage negative supply to provide battery feed and ringing signals to telephones. These subscriber line power (SLP) circuits are bulky and normally include a driver circuit, a power transistor, a power inductor or transformer, one or more rectifiers, a compensation network, input (CIN) and output (GOUT) capacitors and an optional current limit resistor (RLIM). A programmable SLP circuit typically employs an inverting buck-boost, inverting-boost, or flyback technique to convert a positive input voltage, commonly 5-15V, to a negative voltage (VBAT), commonly −24 to −100V.
The subscriber line power supply is controlled by a DC-DC controller which can be a part of the SLAC functionality. The DC-DC controller may include an error amplifier and a transistor driver. The DC-DC controller provides dynamic control to the switcher circuit so that the output voltage (VBAT) corresponds to the state of the telephone line. For example, if the telephone is idle (on-hook), VBAT is normally set to −48VDC. If the telephone set goes off-hook, VBAT is set to a voltage that provides a programmable current to the line, such as 25 mA, irrespective of the length of the telephone loop. If the telephone needs to be rung (for an incoming call), VBAT may go up to −100V in order to provide the SLIC ringing amplifier enough headroom for a 60 Vrms sinusoidal ringing signal. The DC-DC controller adjusts the switching frequency and duty cycle limit using pulse width modulation (PWM) to obtain the desired VBAT voltage and/or supply current for the given state of the telephone line. Sophisticated algorithms are employed to ensure efficiency and to detect and respond to fault conditions. The subscriber line power (SLP) circuit is commonly implemented using discrete components, many of which are large and bulky. Such circuits typically take up 10-20 cm2 on a printed circuit board.
The same issues are also present in other telecommunications applications, such as Power over Ethernet (PoE) Powered Devices (PD), whereby available ICs do not provide complete system solutions and modules are large and expensive. A PoE PD interface controller, which may be integrated on the same device as the DC-DC controller includes circuitry and logic for inrush current limit, and signature and classification according to industry standards.
Given that subscriber line circuits are used in very large numbers (tens of millions per year), there has been a commercial need to reduce the size of these circuits and provide modules that integrate as much functionality as possible (SLIC, SLAC, SLP). This need also extends to integrating some or all of the external components that are required by the SLIC and SLAC that are not a part of the switcher circuit (such as filter capacitors, protection, EMC capacitors, and others). The resulting devices are packaged modules that can be integrated into the end product (such as VoIP boxes or CO line cards) with minimal design effort.
Conventional modules use a PCB or ceramic substrate to connect the components that form the subscriber circuit. Such modules are generally expensive due to the added cost of the PCB or substrate material, but serve a commercial need of providing a more complete “drop-in” solution than what is possible with SLIC and SLAC ICs by integrating the high-voltage switcher circuit.
Conventional integrated subscriber line systems are not complete, as many use external components (e.g., inductors), they are expensive due to the cost of the substrate, and they fail to offer optimum thermal dissipation. The package sizes are also fairly large when the inductor and other external components are added.
This section of this document is intended to introduce various aspects of art that may be related to various aspects of the disclosed subject matter described and/or claimed below. This section provides background information to facilitate a better understanding of the various aspects of the disclosed subject matter. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art. The disclosed subject matter is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.
The following presents a simplified summary of the disclosed subject matter in order to provide a basic understanding of some aspects of the disclosed subject matter. This summary is not an exhaustive overview of the disclosed subject matter. It is not intended to identify key or critical elements of the disclosed subject matter or to delineate the scope of the disclosed subject matter. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.
One aspect of the disclosed subject matter is seen in an apparatus including a metal frame, a switching power circuit, and at least one semiconductor die implementing a communication interface. The metal frame includes a plurality of external pads, and a plurality of base pads coupled to selected external pads. The switching power circuit is mounted to selected base pads and includes an input terminal, an output terminal, an energy storage device mounted to a first subset of the base pads and coupled to the output terminal, and a switching element mounted to a second subset of the base pads and coupled to the input terminal and the energy storage element. The at least one semiconductor die provides a control signal to the switching device to control an output voltage present at the output terminal.
The disclosed subject matter will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and:
While the disclosed subject matter is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the disclosed subject matter to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the disclosed subject matter as defined by the appended claims.
One or more specific embodiments of the disclosed subject matter will be described below. It is specifically intended that the disclosed subject matter not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. Nothing in this application is considered critical or essential to the disclosed subject matter unless explicitly indicated as being “critical” or “essential.”
The disclosed subject matter will now be described with reference to the attached figures. Various structures, systems and devices are schematically depicted in the drawings for purposes of explanation only and so as to not obscure the disclosed subject matter with details that are well known to those skilled in the art. Nevertheless, the attached drawings are included to describe and explain illustrative examples of the disclosed subject matter. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than that understood by skilled artisans, such a special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase.
Referring now to the drawings wherein like reference numbers correspond to similar components throughout the several views and, specifically, referring to
The switching power circuit 4 generally includes a switching element, such as a transistor, and an energy storage device, such as a capacitor, as described below in greater detail. The power controller 6 implements a switching technique, such as pulse width modulation, to control the frequency and duty cycle of the switching transistor to affect the storage of energy in the energy storage device (e.g., capacitive and/or inductive elements) to generate the output voltage, Vout. The communication interface die 2 directs the operation of the power controller 6 to control the output voltage. The input voltage may be received from an external source or it may be generated within the device 1, such as by the communication interface die 2. The output voltage may be used internally within the SiP device 1, such as by the communication interface die 2. Alternatively or additionally, the output voltage may be available on an external output of the SiP device 1 for powering an external device or load. Exemplary applications for the SiP device 1 include a telephony line interface, a power over Ethernet (POE) device, or a lighting controller.
In a first illustrative embodiment shown in
A simplified functional block diagram of the SLIC 25, SLAC 30, and SLP 35 is illustrated in
The general operation and configuration of SLAC devices is also known to those of ordinary skill in the art, so only a high level description is provided. The SLAC 30 provides higher-level functions, such as audio signal conversion and processing, worldwide impedance matching, and call control signal generation and detection. The SLAC 30 includes a DC-DC controller 75 (e.g., the power controller 6 of
In general, the SLP 35 implements the switching power circuit 4 of
The switching power circuit 4 illustrated in
Turning now to
The circuitry for supporting the SLIC 25 includes the EMC filter 50 of
Circuitry for supporting the SLAC 30 includes a resistor 205 is used to set the current reference in the SLAC 30, a reference capacitor 210 (e.g., a ceramic capacitor) connected between the internally-generated precision reference voltage, VREF, of the SLAC 30 and ground to remove high-frequency noise components, and a filtering capacitor 215 (e.g., a ceramic capacitor) used to form a low-pass filter to remove noise and voice signals from the command signal to the DC-DC controller 75.
The input capacitor 150 shown in
External pin pads 265 are provided to allow the use of an external inductor (not shown). A base pad 270 is provided for efficient heat transfer and a high current connection for the switching transistor 130. High voltage isolation gaps 275 are provided for separating high and low voltage components. As seen in
Turning now to
As shown in
As shown in
The use of the metal frame 8, 45 described herein allows the communication interface semiconductor die 2 and components used in implementing the switching power circuit 4 and power controller 6 to be packaged without the need for a substrate to support the metal interconnections. For example, the metal frame 8, 45 may be a lead frame or a sintered silver frame. The metal microstructure provides all of the necessary interconnections. The particular processes used to generate the metal frame 8, 45, mount the die 2 and other components, and complete the packaging of the SiP device 1 are known to those of ordinary skill in the art. In general, the metal frame 8 including the external pin pads 46, the base pads 47, and the bond wires 48 and the components mounted thereto are encapsulated with a resin or polymer material to complete the package. The use of the metal frame 8, 45 eliminates the need to employ a printed circuit board or a ceramic substrate to support some or all of the components and interconnections, thereby allowing a reduced package size and/or reduced cost.
The particular embodiments disclosed above are illustrative only, as the disclosed subject matter may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the disclosed subject matter. Accordingly, the protection sought herein is as set forth in the claims below.
