Package for integrated circuit with internal matching

ABSTRACT

An integrated circuit package houses and connects to a die to form an integrated circuit with internal matching. The package comprises a lead frame comprising at least one transmission line, a die paddle, and at least one input lead and at least one output lead. Bond wires connect select locations along the at least one transmission line to ground through impedance matching circuit components located within the integrated circuit to provide an impedance matching network associated with at least one of the output leads. A plastic mold compound substantially encases the lead frame, while exposing the die paddle and the input/output leads. Incorporating the transmission line into the lead-frame avoids having to place the matching network outside of the integrated circuit package. That is, etching the lead frame to provide the transmission line, and placing components (e.g., capacitors, inductors, etc.) of the impedance transform matching circuit within the integrated circuit and connecting the components between select locations on the transmission line and ground is relatively inexpensive.

INFORMATION

DETAILED DESCRIPTION OF THE INVENTION

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a functional block diagram of a prior art matching circuit configuration that provides an output signal on a line . In one embodiment, the output signal on the line is from an RF power amplifier (PA) within an integrated circuit . The integrated circuit provides the output signal on the line to an impedance transformation network (also referred to herein as a “matching network”), which provides an impedance matched output signal on a line . For example, the impedance matched output signal on the line may for example have an output impedance of fifty ohms, whereas the impedance of the signal on the line may for example be two ohms. The impedance matching network includes a plurality of capacitors C1 and C2 that are precisely positioned to provide the required impedance transformation and harmonic filtering. For example, the capacitor C1 is precisely positioned (e.g., to a 0.001″ tolerance) from edge of the integrated circuit , while the distance between capacitors C1 and C2 is also precisely controlled. As set forth above, these positioning constraints lead to a problematic and relatively costly matching network that is external to the integrated circuit .

FIG. 2 is a cut-a-way top view of a first integrated circuit that includes a first die , and a second die within a plastic package. The first die provides an output signal via bond wires , to a first transmission line located on a lead frame (e.g., etched copper). The second die provides an output signal via bond wires , to a second transmission line located on the lead frame. The lead frame also includes a plurality of input/output (I/O) leads (e.g., -). Bond wires interconnect bonding pads on the dies and the I/O leads. According to an aspect of the present invention, the lead frame also includes at least one transmission line (e.g., 0.1 mm thick in non-exposed areas, and 0.2 mm thick in exposed areas) that cooperates with circuit components within the integrated circuit to provide an integrated circuit with internal matching. Specifically, in this embodiment matching circuit components such as capacitors and/or inductors (not shown) located on the first die are connected to the first transmission line . For example, a first capacitor located on the first die is connected to a first selected location on the transmission line by bond wires , . Two bond wires are shown in this embodiment for current handling. However, a skilled person will recognize of course that more or less bond wires may be used to connect the matching circuit component on the die to the transmission line, depending upon the current handling required. In addition, a second capacitor (now shown) may be located on the die and connected to a second location (e.g., location ) on the transmission line by bond wires (not shown) to provide a matching circuit that is functionally similar to the circuit illustrated in FIG. . However, in the embodiment of FIG. 2, the matching network is located within the integrated circuit. That is, the integrated circuit of FIG. 2 includes internal matching.

The second die may also include an internal matching network that is established by connecting a matching circuit component(s) within the second die , to the transmission line for example via bond wires , .

FIG. 3 is a functional block diagram illustration of the internal matching network associated with the first die illustrated in FIG. . For example an output amplifier located on the die provides an output signal that is conducted by the transmission line to an I/O lead . A first lead of a capacitor located on the die is connected to a first select location on the transmission line via the bond wires , . A second lead of the capacitor is connected to a first electrical potential, for example ground. Significantly, this provides an impedance matching circuit that is located within the integrated circuit .

FIG. 4 is a cut-a-way top view of a second integrated circuit that includes a die (not shown in FIG. ), that is placed onto a die paddle of a lead frame (e.g., etched copper) that includes plurality of I/O leads (e.g., -). Interconnect bonding pads located on the die are connected for example via bond wires to the I/O leads. The lead frame also includes a first transmission line shown in cross hatch. In this embodiment, the package also includes a second transmission line that is also not exposed on the exterior of the package. The first transmission line is associated with a first output signal from the package, while the second transmission line is associated with a second output signal from the package. Matching circuit components such as capacitors and/or inductors (not shown) located on the die and associated with the first output signal, are connected between a first electrical potential (e.g., ground) and at least one select location on the first transmission line .

FIG. 5 illustrates a section taken along line A—A in FIG. 4. A die is located on the paddle , and at least one bond wire connects lead and a bond pad (not shown) on the die . FIG. 6 illustrates a bottom view of the second integrated circuit. As shown, the lead frame includes the paddle and the plurality of I/O leads, for example -. Referring to FIGS. 5 and 6, the package also includes a plurality of exposed wire bond support structures - that represent select locations along the transmission lines at which the matching circuit components may be connected. For example, in one embodiment, these support structures (e.g., etched copper) are connection points for bond wires between the matching components on the die, and the transmission lines within the lead frame of the package. For example, bonding wire (FIG. 5) runs between a matching component (e.g., a capacitor) on the die and the support structure (i.e., a select location on the transmission line ).

FIG. 7 is a side view of the package of FIG. .

FIG. 8 is a cut-a-way top view of a third integrated circuit that includes a die , and a lead frame of a third plastic package. FIG. 9 is a top view of the lead frame of FIG. 8 shown in cross hatch. The lead frame includes a die paddle and a plurality of I/O leads -. The lead frame also includes a transmission line that connects an output on the die to selected I/O leads -. In this embodiment, the die output is connected to the transmission line by a plurality of bond wires . The die includes at least one component (e.g., a capacitor, inductor, etc) of an impedance matching/transformation network. The network matching component within the die is connected to a first select location along the transmission line . As a result, a circuit configuration as shown in FIG. 3 is provided. Depending upon the impedance matching and filtering requirements, the matching circuit component within the die may be connected to the transmission line at one of a plurality of select locations - along the transmission line, rather than at the selected location . In the embodiment of FIG. 8, the integrated circuit is 4 mm×4 mm (i.e., L is equal to 4 cm). As shown in FIG. 8, the path length of the transmission line will vary pending upon the select location (e.g., ) along the transmission line that the matching circuit component is connected to.

FIG. 10 is a bottom view of the lead frame of FIG. 8 shown in cross hatch. In this view, support structures associated with the select locations , along the transmission line (FIG. 9) are exposed on the underside of the integrated circuit .

FIG. 11 is a cut-a-way top view of a fourth integrated circuit that includes a die , and a lead frame of a fourth plastic package. This embodiment is substantially the same as the embodiment illustrated in FIGS. 8-10, with the principal exception that an internal matching network component (e.g., a capacitor) is located between die paddle and a first select location on the transmission line . That is, the internal matching circuit component is not located on the die. However, the internal matching circuit is still resident within the integrated circuit to provide the internal matching.

FIG. 12 is a cut-a-way top view of a fifth integrated circuit that includes a die , and a lead frame of a fifth plastic package. This embodiment is substantially the same as the embodiments illustrated in FIGS. 8-10, and FIG. 11, with the principal exception that a first internal matching network component (e.g., a capacitor) is located between a die paddle and a first select location on the transmission line , and second internal matching network component (not shown) is located within the die and connected to a second select location on the transmission line.

FIG. 13 is a functional block diagram illustration of the internal matching network associated with the integrated circuit of FIG. . For example, an output amplifier located on the die provides an output signal that is conducted by the transmission line to the I/O lead . A first lead of a capacitor located on the die is connected to the second select location on the transmission line via bond wires . A second lead of the capacitor on the die is connected to a first electrical potential, for example ground. A first lead of the capacitor is connected to the first selected location on the transmission line , while a second lead of the capacitor is connected to the die paddle (i.e., ground).

Advantageously, the integrated circuit and package of the present invention provide internal impedance matching, thus for example freeing a handset manufacturer (or board manufacturer) from having to provide room on the board for the impedance transformation matching circuitry.

Although the present invention has been discussed in the context of a package for power amplifiers for wireless handsets, it is contemplated that the many other applications will find it desirable to replace applications that require impedance matching, conventionally performed on a circuit board or as lumped element components, with matching circuitry contained within the integrated circuit. Advantageously, this obviates many of the manufacturability problems associated with having to precisely position the components of the matching circuit. In addition, although the matching network components have been connected between the transmission line and ground, the first electrical potential does not necessarily have to be ground.

Although the present invention has been shown and described with respect to several preferred embodiments thereof, various changes, omissions and additions to the form and detail thereof, may be made therein, without departing from the spirit and scope of the invention.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates a functional block diagram of a prior art matching circuit configuration for an RF output signal;

FIG. 2 is a cut-a-way top view of a first integrated circuit that includes a first die, and a second die within a first plastic package;

FIG. 3 is a functional block diagram illustration of the internal matching network associated with the first die illustrated in FIG. 2;

FIG. 4 is a cut-a-way top view of a lead frame of a second integrated circuit that provides at least one output signal;

FIG. 5 illustrates a section taken along line A—A in FIG. 4;

FIG. 6 illustrates a bottom view of the second plastic package of FIG. 4;

FIG. 7 illustrates a side view of the package of FIG. 6;

FIG. 8 is a cut-a-way top view of a lead frame of a third integrated circuit that includes an internal matching circuit located within a die;

FIG. 9 is a top view of the lead frame of FIG. 8 shown in cross hatch;

FIG. 10 is a bottom view of the lead frame of FIG. 8 with exposed sections of the lead frame shown in cross hatch;

FIG. 11 is a cut-a-way top view of a lead frame of a fourth integrated circuit that includes an internal matching network located between the die paddle and a first select location on the transmission line;

FIG. 12 is a cut-a-way top view of a lead frame of a fifth integrated circuit that includes a first internal matching network component located between the die and a first select location on the transmission line, and a second internal matching network component located between the die paddle and a second select location on the transmission line; and

FIG. 13 is a functional block diagram illustration of the internal matching network associated with the integrated circuit of FIG. .

CLAIMS

1. An internally matched integrated circuit, comprising: a package that includes a lead frame comprising at least one input signal lead, at least one output signal lead, and at least one transmission line that is connected to said at least one output signal lead; and a die that is electrically connected to and housed within said package, and provides a signal onto said at least one transmission line; wherein a select location along said at least one transmission line is electrically connected to a first electrical potential through an impedance matching circuit located on said die.

2. The internally matched integrated circuit of claim 1, wherein said select location along said transmission line and said impedance matching circuit are connected via at least one bond wire.

3. The internally matched integrated circuit of claim 2, wherein said impedance matching circuit comprises a capacitor.

4. The internally matched integrated circuit of claim 2, wherein said impedance matching circuit comprises an inductor.

5. The internally matched integrated circuit of claim 2, wherein said die comprises a GaAs device.

6. The internally matched integrated circuit of claim 2, wherein said die comprises a silicon die.

7. An internally matched integrated circuit, comprising: a package that includes a lead frame comprising at least one transmission line, a die paddle, at least one input signal lead, and at least one output signal lead that is connected to said at least one transmission line; and a die that is electrically connected to and housed within said package, and provides a signal onto said at least one transmission line; wherein at least one select location on said at least one transmission line is electrically connected to said die paddle through an impedance matching circuit.

8. The internally matched integrated circuit of claim 7, wherein said impedance matching circuit comprises a capacitor having a first lead connected to said select location along said transmission line, and a second lead connected to said die paddle.

9. The internally matched integrated circuit of claim 7, wherein said impedance matching circuit comprises an inductor having a first lead connected to said select location along said transmission line, and a second lead connected to said die paddle.

10. The internally matched integrated circuit of claim 7, wherein said impedance matching circuit includes a first lead connected to said select location along said transmission line, and a second lead connected to said die paddle.

11. The internally matched integrated circuit of claim 7, wherein said transmission line has a length of at least one millimeter.

12. An integrated circuit package that houses and electrically connects to a die to form an integrated circuit with internal matching, said package comprising: a lead frame comprising a transmission line, a die paddle, a plurality of input leads, and a plurality of output leads at least one which is connected to said transmission line, wherein at least one select location alone said transmission line is electrically connected to a first electrical node through an impedance matching circuit contained within said package to provide an impedance matching network associated with said at least one of said output leads connected to said transmission line: and a member that substantially encases said lead frame, while exposing said die paddle and said input leads and said output leads, wherein said first electrical node is located on said die paddle, and said impedance matching circuit includes a capacitor having a first lead connected to said die paddle and a second lead connected to said select location on said transmission line.

13. The integrated circuit package of claim 12, wherein said transmission line comprises etched copper.

14. The integrated circuit package of claim 12, wherein said impedance matching circuit comprises a capacitor.

15. The integrated circuit package of claim 12, wherein said impedance matching circuit comprises an inductor.

16. The integrated circuit package of claim 12, wherein said impedance matching circuit is located within the die mounted on said die paddle.

COPYRIGHT

User acknowledges that Fairview Research and its third party providers retain all right, title and interest in and to this xml under applicable copyright laws. User acquires no ownership rights to this xml including but not limited to its format. User hereby accepts the terms and conditions of the License Agreement.