High-performance package for monolithic microwave integrated circuits

• US 4,901,041 A
• Filed: 09/30/1988
• Issued: 02/13/1990
• Est. Priority Date: 09/30/1988
• Status: Expired due to Term

• Current Assignee: Grumman Aerospace Corporation (Northrop Grumman Corporation)
• Original Assignee: Grumman Corp. (Northrop Grumman Corporation)
• Inventors: Pengelly, Raymond S.
• Primary Examiner(s): GENSLER, PAUL L
• Application Number:
  US07/251,446
• Time in Patent Office: 501 Days
• Field of Search: 333/33, 333/204, 333/238, 333/246, 333/247, 357/74, 357/80, 361/401, 174/52.4
• US Class Current: 333/33
• CPC Class Codes: H01L 23/66 High-frequency adaptations
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H01P 1/2039 Galvanic coupling between Input/Output
• CPC Class Codes: H01P 5/085 Coaxial-line/strip-line transitions

Abstract

The present invention incorporates a specially-designed low-pass filter into the feedthrough of a monolithic microwave integrated circuit (MMIC) to provide compensation for discrepancies from the impedance required for an MMIC package to be matched to a transmission line. The compensation allows all parameters to be adjusted and the complete filter to be printed.

The main features of the invention include minimum width for the under-wall conductor and brazing metallization, two open-circuited stubs at the package-die interface for wire bonding ease, and metal-filled vias connecting the ground plane base and the lid sealing ring to bring the lid sealing ring to RF ground.

The present ivention also includes a method for designing the desired feedthrough that obviates the need for scale-model feedthrough design before printing, a prior art method that requires precision in the scale model. An electrical model of a feedthrough is first derived. The electrical model is then adjsuted according to the parameters desired for a new, compensated feedthrough using any known method, including software such as Touchstone. Finally, the new feedthrough is fabricated based upon the adjusted electrical model.

Claims

1. A compensated feedthrough for a monolithic microwave integrated circuit package, comprising:

a first microstrip transmission line section including a first microstrip signal conductor;

a pseudostrip transmission line section electrically connected to said first microstrip transmission line section, including a pseudostrip signal conductor electrically connected to said first microstrip signal conductor, wherein at least a portion of the length of said pseudostrip signal conductor is no greater than 6 mil in width; and

a second microstrip transmission line section electrically connected to said pseudostrip transmission line section, including a second microstrip signal conductor electrically connected to said pseudostrip signal conductor, said second microstrip signal conductor having first and second ends, wherein said first end is electrically connected to said pseudostrip conductor and said second end is arranged to form two open-circuited studs.

2. A monolithic microwave integrated circuit package, comprising:

a die cavity;

a transition portion substantially surrounding the die cavity in two dimensions, said transition portion including a lid sealing ring and a ground plane base separated by a dielectric material, said dielectric material including at least one aperture formed in the dielectric material to enable electric connection of the sealing ring to the ground plane base, wherein said aperture is filled with electrically conductive material to substantially reference the lid sealing ring electrically to the ground plane base.

3. A monolithic microwave integrated circuit package as claimed in claim 2, wherein said transition portion includes at least one compensated feedthrough, said compensated feedthrough comprising:

a first microstrip transmission line section including a first microstrip signal conductor;

a pseudostrip transmission line section electrically connected to said first microstrip transmission line section, including a pseudostrip signal conductor electrically connected to said first microstrip signal conductor, wherein at least a portion of said pseudostrip signal conductor is no greater than 6 mil in width; and

a second microstrip transmission line section electrically connected to said pseudostrip transmission line section, including a second microstrip signal conductor having first and second ends, wherein said first end is electrically connected to said pseudostrip signal conductor and said second end is arranged to form two open-circuited stubs at the interface between the second microstrip transmission line section and the die cavity.

4. A monolithic microwave integrated circuit package, comprising:

a die cavity;

a waveguide transition portion substantially surrounding the die cavity in two dimensions, wherein said waveguide transition portion includes at least one compensated feedthrough, said compensated feedthrough comprising;

a first microstrip transmission line section including a first microstrip signal conductor;

a pseudostrip transmission line section electrically connected to said first microstrip transmission line section, including a pseudostrip signal conductor electrically connected to said first microstrip signal conductor, wherein at least a portion of the length of said pseudostrip signal conductor is no greater than 6 mil in width; and

a second microstrip transmission line section electrically connected to said pseudostrip transmission line section, including a second microstrip signal conductor having first and second ends, wherein said first end is electrically connected to said pseudostrip signal conductor and said second end is arranged to form two open-circuited stubs at the interface between the second microstrip transmission line section and the die cavity.

5. A method for designing a compensated feedthrough for an integrated circuit package, comprising the steps of:

(a) establishing a desired equivalent electric circuit representing the electrical characteristics for a desired feedthrough;

(b) designing physical characteristics for the desired feedthrough based upon the desired equivalent electrical circuit;

(c) building the desired feedthrough having said physical characteristics;

(d) testing the desired feedthrough; and

(e) adjusting the feedthrough by comparing the characteristics obtained by testing of the desired feedthrough with the characteristics of the desired equivalent electrical circuit.

6. A method for designing a compensated feedthrough for an integrated circuit package as claimed in claim 5, further comprising, before step (a) the step of:

(a) establishing a temporary equivalent electrical circuit representing the electrical characteristics of an existing feedthrough,

wherein said desired electrical circuit is established by adjusting the temporary electrical circuit to achieve the desired electrical characteristics.