Compact multilayer BALUN for RF integrated circuits

• US 6,396,362 B1
• Filed: 01/10/2000
• Issued: 05/28/2002
• Est. Priority Date: 01/10/2000
• Status: Active Grant

• Current Assignee: MediaTek, Inc.
• Original Assignee: International Business Machines Corporation
• Inventors: Imbornone, James, Mourant, Jean-Marc
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): TAKAOKA, DEAN O
• Application Number:
  US09/480,032
• Time in Patent Office: 869 Days
• Field of Search: 333/26,25 336/200 437/60
• US Class Current: 333/25
• CPC Class Codes: H01F 2021/125 Printed variable inductor with taps, e.g. for VCO
• CPC Class Codes: H03H 7/42 Networks for transforming balanced signals into unbalanced signals and vice versa, e.g. baluns

Abstract

A compact BALUN transformer comprises a primary and a secondary conductor loop. Each of these loops are disposed in a substantially flat spiral configuration. However, one of these loops, either the primary or the secondary, is preferably disposed in a multi-layer (stacked) configuration. The stacking of at least one of the primary or secondary layers in a multi-layer arrangement provides an increase of impedance in one of the loops. This increased impedance for impedance matching purposes comes with the advantage that parasitic capacitance between primary and secondary layers as would normally be introduced in a multi-layer configuration is absent. In another embodiment of the present invention, both conductor loops are disposed in a multi-layer configuration. Such configurations are particularly useful for 1 to 1 impedance matching conditions and for somewhat lower frequency BALUN circuits.

Claims

1. A balun transformer comprising:

a first loop conductor having a first portion wound in a flat spiral pattern in a first plane and a second portion wound in a flat spiral pattern with the same winding orientation as said first portion of said first loop conductor in a second plane parallel to said first plane; and

a second loop conductor wound in a flat spiral pattern in said first plane horizontally adjacent said first portion of said first loop conductor,

wherein at least one of said conductor loops is disposed in a rectangular pattern.

2. A balun transformer comprising:

a first loop conductor having a first portion wound in a flat spiral pattern in a first plane and a second portion wound in a flat spiral pattern with the same winding orientation as said first portion of said first loop conductor in a second plane parallel to said first plane; and

a second loop conductor wound in a flat spiral pattern in said first plane horizontally adjacent said first portion of said first loop conductor,

wherein said transformer is operative at a frequency of approximately 850 megahertz, provides a 4 to 1 impedance matching and is configured in a rectangular pattern which is approximately 235 microns on each side.

3. A balun transformer comprising:

a first loop conductor having a first portion wound in a flat spiral pattern in a first plane and a second portion wound in a flat spiral pattern with the same winding orientation as said first portion of said first loop conductor in a second plane parallel to said first plane; and

a second loop conductor having a first portion wound in a flat spiral pattern in said first plane horizontally adjacent said first portion of said first loop conductor and a second portion wound in a flat spiral pattern with the same winding orientation as said first portion of said second loop conductor in a second plane horizontally adjacent said second portion of said first loop conductor,

wherein said transformer is operative at a frequency of approximately 850 megahertz, provides a 1 to 1 impedance matching and is configured in a rectangular pattern which is approximately 235 microns on each side.