Lowpass filter formed in a multi-layer ceramic

• US 6,970,057 B2
• Filed: 04/02/2004
• Issued: 11/29/2005
• Est. Priority Date: 04/02/2004
• Status: Expired due to Fees

• Current Assignee: Chi Mei Communication Systems Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Chi Mei Communication Systems Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Li, Ko-Mai, Lin, Yo-Shen
• Primary Examiner(s): Ham, Seungsook
• Application Number:
  US10/708,942
• Publication Number:
  US 20050219011A1
• Time in Patent Office: 606 Days
• Field of Search: 333/167, 333177-181, 333/185
• US Class Current: 333/177
• CPC Class Codes: H01F 2017/0026 Multilayer LC-filter
• CPC Class Codes: H03H 2001/0085 Multilayer, e.g. LTCC, HTCC, green sheets
• CPC Class Codes: H03H 7/0123 comprising distributed impedance elements together with lumped impedance elements
• CPC Class Codes: H03H 7/09 Filters comprising mutual inductance
• CPC Class Codes: H05K 1/0306 Inorganic insulating substrates, e.g. ceramic, glass
• CPC Class Codes: H05K 1/162 incorporating printed capacitors
• CPC Class Codes: H05K 1/165 incorporating printed inductors

Abstract

A lowpass filter formed in a multi-layered substrate includes a first capacitor formed on at least one layer of the multi-layered substrate and being electrically connected to a first node, a first inductor being electrically connected to the first capacitor at the first node, and a second inductor being electrically connected to the first inductor and the first capacitor at the first node. In the lowpass filter, negative mutual inductance exists between the first inductor and the second inductor.

Claims

1. A lowpass filter formed in a multi-layered substrate comprising:

a first inductor having one end electrically connected to a first node;

a second inductor having one end electrically connected to a second node;

a third inductor having one end electrically connected to the first node and another end electrically connected to the second node, wherein the third inductor is formed on different layers of the multi-layered substrate than the first and second inductors;

a first capacitor formed on at least one layer of the multi-layered substrate and being electrically connected to the first node and to ground; and

a second capacitor formed on at least one layer of the multi-layered substrate and being electrically connected to the second node and to ground;

wherein negative mutual inductance exists between the first and third inductors and between the second and third inductors.

2. The lowpass filter of claim 1, further comprising:

a first via for electrically connecting the first inductor, the third inductor, and the first capacitor at the first node; and

a second via for electrically connecting the second inductor, the third inductor, and the second capacitor at the second node.

3. The lowpass filter of claim 1, wherein the first capacitor comprises a first metal sheet electrically connected to the first node and a second metal sheet electrically connected to ground, and the second capacitor comprises a third metal sheet electrically connected to the second node and a fourth metal sheet electrically connected to ground.

4. The lowpass filter of claim 1, wherein the first, second, and third inductors are formed out of metal strips.

5. The lowpass filter of claim 4, wherein the metal strips are patterned in spiral shapes.

6. A lowpass filter formed in a multi-layered substrate comprising:

a first layer of the multi-layered substrate comprising a first inductor having one end electrically connected to a first node and a second inductor having one end electrically connected to a second node;

a second layer of the multi-layered substrate comprising a third inductor having one end electrically connected to the first node and another end electrically connected to the second node;

a third layer of the multi-layered substrate comprising a first metal sheet electrically connected to ground and a second metal sheet electrically connected to ground; and

a fourth layer of the multi-layered substrate comprising a third metal sheet electrically connected to the first node and a fourth metal sheet electrically connected to the second node, wherein the first and third metal sheets constitute a first capacitor and the second and fourth metal sheets constitute a second capacitor;

wherein negative mutual inductance exists between the first and third inductors and between the second and third inductors.

7. The lowpass filter of claim 6, further comprising:

a first via for electrically connecting the first inductor, the third inductor, and the first capacitor at the first node; and

a second via for electrically connecting the second inductor, the third inductor, and the second capacitor at the second node.

8. The lowpass filter of claim 6, wherein the first, second, and third inductors are formed out of metal strips.

9. The lowpass filter of claim 8, wherein the metal strips are patterned in spiral shapes.