Local ground plane for high frequency circuits

• US 5,485,036 A
• Filed: 08/03/1994
• Issued: 01/16/1996
• Est. Priority Date: 08/03/1994
• Status: Expired due to Fees

• Current Assignee: Hazeltine Corporation (BAE Systems Plc)
• Original Assignee: Hazeltine Corporation (BAE Systems Plc)
• Inventors: LaRosa, Richard
• Primary Examiner(s): Crane, Sara W.
• Assistant Examiner(s): Clark, S. V.
• Application Number:
  US08/285,571
• Time in Patent Office: 531 Days
• Field of Search: 257/691, 257/728, 257/664
• US Class Current: 257/691
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/4911 the connectors being bonded to at least one common bonding area, e.g. daisy chain
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 23/66 High-frequency adaptations
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/49 of a plurality of wire connectors
• 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 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01037 Rubidium [Rb]
• CPC Class Codes: H01L 2924/1305 Bipolar Junction Transistor [BJT]
• CPC Class Codes: H01L 2924/19041 being a capacitor
• CPC Class Codes: H01L 2924/19107 off-chip wires
• CPC Class Codes: H01L 2924/30107 Inductance
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding

Abstract

A local R.F. ground plane for high frequency active device. The R.F. grounded terminal of each active device is connected directly to its local R.F. ground plane. In the case of a transistor, there are common emitter, common base, or common collector circuits. The common electrode or terminal is connected directly to the local R.F. ground plane. In the case of a FET, the common electrode can be the source, gate or drain. In the case of a thermionic vacuum tube, the common electrode can be the cathode, grid or plate. In the case of a vacuum microelectronic device, the names are still evolving. The local R.F. ground is bypassed to the case of the package near the local R.F. input and/or output connections. This design permits double bond wires from the emitter to the local R.F. ground plane and eliminates parasitic oscillations where the potential oscillation frequency of the active device being protected is at least twice as great as the operating frequency of the package.

Claims

1. An apparatus for a planar circuit, said planar circuit being defined as having a circuit surface, a plurality of electronic components attached to said circuit surface, and having a main ground plane separated therefrom said circuit surface by an insulating substrate, with said main ground plane serving as DC ground for said planar circuit, said apparatus comprising:

at least one of said plurality of electronic components of said planar circuit being an active device, said active device having a bias network, said bias network having a R.F. bypass capacitance, said active device having a potential oscillating frequency that is substantially greater than the operating frequency of said planar circuit, said active device and said bias network attached to said circuit surface;

a local R.F. ground plane, connected between said active device and said bias network of said active device, and positioned between said bias network of said active device and the main ground plane with said local ground plane having a pre-determined surface geometry corresponding to said active device and said bias network wherein said active device has a low inductance path to said local ground plane thereby preventing parasitic oscillations in said planar circuit.

2. The apparatus of claim 1 further comprising an intermediate land and an attached insulating substrate, said intermediate land and its attached substrate connected between said local ground plane and said active device and wherein said active device is first connected to said intermediate land by at least one bond and then said intermediate land is connected to said local ground plane, thereby permitting the use of shorter bond wires than would be obtained by directly connecting said active device to said local ground plane.

3. The apparatus of claim 1 where said active device is connected to said apparatus using a conductive land and said local ground plane further comprising an opening corresponding to the geometry of said conductive land.

4. The apparatus of claim 1 where said active device has an oscillation frequency that is at least twice that of the operating frequency of said planar circuit.

5. The apparatus of claim 1 where said capacitance that is connected between said local R.F. ground plane and said main ground plane is selected in accordance with the operating frequency of said planar circuit.

6. The apparatus of claim 1 wherein said local ground plane has at least one window to accommodate a land.

7. The apparatus of claim 1 wherein at least another one of said plurality of electronic components is associated with said active element and is shielded from said main ground plane by said local R.F. ground plane.

8. The apparatus of claim 1 wherein at least another one of said plurality of said electronic components is associated with said active element, is not connected to said local ground plane, and is shielded from said main ground plane by said local R.F. ground plane.