Wave transmission lines and networks – Coupling networks – With impedance matching
Reexamination Certificate
1999-07-15
2001-12-18
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Coupling networks
With impedance matching
C333S260000, C333S246000, C333S247000
Reexamination Certificate
active
06331806
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement in a microwave circuit package for sealing therein microwave circuitry having monolithic microwave integrated circuits (hereinafter referred to as MMICs), as well as to ribbons and bonding wires for use in fabricating the microwave circuit package.
2. Description of the Related Art
Conventionally, bonding wires having uniform diameters along their lengths, ribbons of uniform thickness and/or mesh ribbons, have been used for mounting high-frequency devices to a metallic substrate in a microwave circuit package.
Japanese Patent Laid-Open Publication No. HEI 1-300546 discloses a microwave circuit package in which electrostatic capacity is provided externally of an area of an MMIC chip by forming a dielectric layer between a metallic substrate and a biasing direct current (DC) terminal.
In such a microwave circuit package, discontinuity of impedance is likely to arise at places where ribbons and bonding wires are provided. As a result, it is likely that components such as MMICs vary in their bare characteristics after mounting or assemblage thereof, leading to deteriorated characteristics of the components.
Certain occasions arise wherein it is desired that a microwave circuit package be fabricated using metallic substrates, MMICs and bonding wires which are altered in their materials, while rendering the microwave circuit package to be compatible with a separate microwave circuit package fabricated using the same components but not involving such changes in material, by varying the post-mounting high-frequency characteristics of the MMIC and so forth.
The post-mounting high-frequency characteristics of the MMICs may be varied by changing the lengths of the ribbons and bonding wires. However, connection through the bonding wires requires of the latter to be gently curved in a proper manner. In addition, length alteration of the bonding wires is limited due to the limited space within the microwave circuit package. Another possible approach would be to change the spacing between the components such as the MMICs to allow alteration of the lengths of the ribbons. However, the space alteration is also limited and hence is not an effective solution.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a ribbon and a bonding wire which can be connected to an input and an output of a microwave circuit and allow intentional variation of the frequency characteristics of the microwave circuit.
Another object of the present invention is to provide a microwave circuit package having a metallic substrate and sealing therein an MMIC mounted to the metallic substrate, the microwave circuit package further comprising a circuit or circuit element having a ribbon and/or a bonding wire assembled thereinto for allowing intentional variation of the frequency characteristics of the resulting microwave circuit.
According to the present invention, there are provided a ribbon and a bonding wire, the width and thickness of which are varied at at least a portion other than a portion thereof used for bonding. Specifically, the ribbon width and bonding wire thickness may be varied continuously or discontinuously. The ribbon and bonding wire involving such variation may be used for the connection of a high-frequency input/output of a microwave circuit sealed in a microwave circuit package.
Effects resulting from the variation of the ribbon width and bonding wire thickness at portions other than portions thereof used for bonding may be explained as below:
The ribbon and bonding wire have such components as resistance R and reactance X, as well as the total opposition, namely, impedance Z which is a combination of the former two. Using resistance R and reactance X, the correlations may be represented by Z=(R
2
+X
2
)
½
. Magnitude of reactance X may be represented by X=&ohgr;L with respect to inductance L and by X=1/&ohgr;C with respect to capacitance C.
Reactance X is a function of frequency f (or angular frequency &ohgr;=2&pgr;f). In a circuit of high frequency (1-100 GHz) such as a microwave circuit, it is possible to vary reactance X significantly and hence impedance Z by slightly varying inductance L through variation of the ribbon width and bonding wire thickness.
Accordingly, by varying the width of the ribbon and the thickness of the bonding wire at portions other than portions thereof used for bonding, it becomes possible to intentionally vary the discontinuity of impedance within a microwave circuit and to thus vary the frequency characteristics of the microwave circuit
Consequently, it also becomes possible to vary impedance in the respective microscopic portions of the ribbon and bonding wire gradually (or continuously) by continuously varying the ribbon width and bonding wire thickness.
By varying the ribbon width and bonding wire thickness discontinuously, it becomes possible to vary impedance in the respective microscopic portions of the ribbon and bonding wire suddenly (or in a phased fashion).
In a preferred form, the MMIC sealed within the microwave circuit package according to the present invention is provided with a high-frequency compensating circuit positioned closely to the bonding portions of the ribbon and bonding wire. Apart from varying the frequency characteristics of the microwave circuit through the variation of the ribbon width and bonding wire thickness, provision of such a high-frequency compensating circuit also makes it possible to independently vary the frequency characteristics of the microwave circuit in that impedance can be regulated using the high-frequency compensating circuit. The high-frequency compensating circuit may be comprised of an impedance regulating stub. As a result, it become possible to delicately vary the frequency characteristics of the microwave circuit using the ribbon, bonding wire and the high-frequency compensating circuit having different characteristics.
Alternatively, the high-frequency input/output of the microwave circuit within the microwave circuit package may be connected by means of the ribbon varied in thickness at at least a portion other than a portion thereof used for bonding. By varying the thickness of the ribbon at a portion other than a portion thereof used for bonding, it becomes possible to intentionally vary the discontinuity of impedance within the microwave circuit so as to effect the intentional variation of the frequency characteristics of the microwave circuit.
The high-frequency input/output of the microwave circuit within the microwave circuit package according to the present invention may desirably be connected by means of the ribbon varied in width at a portion other than a portion thereof used for bonding and having opposed ends narrower than the widths of the microwave circuit high-frequency input/output ends to which the ribbon is to be bonded. By varying the width of the ribbon at a portion other than a portion thereof used for bonding, it becomes possible to intentionally vary the discontinuity of impedance in the microwave circuit to thereby intentionally vary the frequency characteristics of the microwave circuit. By making the widths of the opposed ribbon ends narrower than the widths of the high-frequency input/output ends to which the ribbon is to be bonded, positioning of the ribbon upon bonding thereof becomes easy, leading to reduced production costs of the microwave circuit package.
The microwave circuit package according to the present invention includes a support member disposed on the metallic substrate for supporting the ribbon thereon. By disposing the support member on the metallic substrate for supporting the ribbon, increased mechanical strength may be imparted to the ribbon, thus resulting in increased reliability of the microwave circuit. When there is a height difference between the MMICs and other components, a sloped surface corresponding to the height difference may be provided on the support member so that the ribbon can be posit
Shingyoji Masahito
Takeuchi Nobuyoshi
Honda Giken Kogyo Kabushiki Kaisha
Lee Benny
Lyon & Lyon LLP
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