Duplexer filter with an alternative signal path

• US 6,559,735 B1
• Filed: 10/31/2000
• Issued: 05/06/2003
• Est. Priority Date: 10/31/2000
• Status: Expired due to Term

• Current Assignee: CTS Corporation
• Original Assignee: CTS Corporation
• Inventors: Hoang, Truc, Vangala, Reddy
• Primary Examiner(s): LEE, BENNY T
• Application Number:
  US09/702,420
• Time in Patent Office: 917 Days
• Field of Search: 333/134, 333/206, 333/202
• US Class Current: 333/134
• CPC Class Codes: H01P 1/2136 using comb or interdigital filters; using cascaded coaxial cavities H01P1/2131, H01P1/2135 take precedence

Abstract

The present invention is a preferred monoblock ceramic bandpass duplexer filter. The preferred filter has at least three I/O pads. One of the pads is coupled to an antenna, another is connected to a transmission circuit and the last pad is connected to a receive circuit. The filter is comprised of two sections: a transmission section and a receive section. The transmission and receive sections include resonators disposed on respective sides of the antenna pad. A first alternative signal path is disposed adjacent the ends of the transmission resonators. A second alternative signal path is disposed adjacent to the ends of the receive resonators. Each alternative signal path couples adjacent and non-adjacent resonators. A further feature of the filter of the present invention includes a shunt zero resonator for the transmission section. To the contrary, the present invention allows the elimination of a shunt zero resonator for the receive section of the filter.

Claims

1. A monoblock duplexer filter adapted for connection to an antenna, a transmitter and a receiver for filtering an incoming signal from the antenna to the receiver and for filtering an outgoing signal from the transmitter to the antenna, the duplexer filter comprising a parallelepiped dielectric block having a top, a bottom and four sides, and including:

an antenna electrode pad on the block;

a transmit section extending between the antenna electrode and a first side of the block;

a receive section extending between the antenna electrode and a second side of the block opposing the first side;

each section having a plurality of through-hole resonators, each through-hole resonator extending between the top and the bottom;

a transmit electrode pad on the block and spaced apart from the antenna electrode along the length of the block and positioned in the transmit section;

a receive electrode pad on the block and spaced apart from the antenna electrode along the length of the block and positioned in the receiver section;

an isolated resonator by-pass electrode plating on the top in the transmit section and extending from a position adjacent a first resonator of the plurality of through-hole resonators to a position adjacent a second resonator of the plurality of through-hole resonators, the first and second resonators being separated by at least one resonator therebetween; and

a second isolated resonator by-pass electrode plating on the top in the receive section and extending from a position adjacent a third resonator of the plurality of through-hole resonators to a position adjacent a fourth resonator of the plurality of through-hole resonators in the receive section, the third and fourth resonators being separated by at least one resonator therebetween.

2. A monoblock duplexer filter adapted for connection to an antenna, a transmitter and a receiver for filtering an incoming signal from the antenna to the receiver and for filtering an outgoing signal from the transmitter to the antenna, the duplexer filter comprising a parallelepiped dielectric block having a top, a bottom and four sides, and including:

an antenna electrode pad on the block;

a transmit section extending between the antenna electrode and a first side of the block;

a receive section extending between the antenna electrode and a second side of the block opposing the first side;

each section having a plurality of through-hole resonators, each through-hole resonator extending between the top and the bottom;

a transmit electrode pad on the block and spaced apart from the antenna electrode along the length of the block and positioned in the transmit section;

a receive electrode pad on the block and spaced apart from the antenna electrode along the length of the block and positioned in the receiver section; and

an isolated resonator by-pass electrode plating on the top in the transmit section and extending from a position adjacent a first resonator of the plurality of through-hole resonators to a position adjacent a second resonator of the plurality of through-hole resonators, the first and second resonators being separated by at least one resonator therebetween,

wherein at least one of the plurality of resonators of the transmit section is a shunt zero resonator which is positioned between the first side of the block and the transmit electrode pad.

3. A monoblock duplexer filter adapted for connection to an antenna, a transmitter and a receiver for filtering an incoming signal from the antenna to the receiver and for filtering an outgoing signal from the transmitter to the antenna, the duplexer filter comprising a parallelepiped dielectric block having a top, a bottom and four sides, and including:

an antenna electrode pad on the block;

a transmit section extending between the antenna electrode and a first side of the block;

a receive section extending between the antenna electrode and a second side of the block opposing the first side;

each section having a plurality of through-hole resonators, each through-hole resonator extending between the top and the bottom;

a transmit electrode pad on the block and spaced apart from the antenna electrode along the length of the block and positioned in the transmit section;

a receive electrode pad on the block and spaced apart from the antenna electrode along the length of the block and positioned in the receiver section; and

an isolated resonator by-pass electrode plating on the top in the transmit section and extending from a position adjacent a first resonator of the plurality of through-hole resonators to a position adjacent a second resonator of the plurality of through-hole resonators, the first and second resonators being separated by at least one resonator therebetween,

wherein the by-pass electrode plating is elongate and rectangular in shape.

4. The filter according to claim 3 having nine through-hole resonators.

5. The filter according to claim 3 wherein the transmit section includes five through-hole resonators and the receive section includes four through-hole resonators.

6. A monoblock duplexer filter adapted for connection to an antenna, a transmitter and a receiver for filtering an incoming signal from the antenna to the receiver and for filtering an outgoing signal from the transmitter to the antenna, the duplexer filter comprising a parallelepiped dielectric block having a top, a bottom and four sides, and including:

an antenna electrode pad on the block;

a transmit section extending between the antenna electrode and a first side of the block;

a receive section extending between the antenna electrode and a second side of the block opposing the first side;

each section having a plurality of through-hole resonators, each through-hole resonator extending between the top and the bottom;

a transmit electrode pad on the block and spaced apart from the antenna electrode along the length of the block and positioned in the transmit section;

a receive electrode pad on the block and spaced apart from the antenna electrode along the length of the block and positioned in the receiver section; and

an isolated resonator by-pass electrode plating on the top in the receive section and extending from a position adjacent a first resonator of the plurality of through-hole resonators to a position adjacent a second resonator of the plurality of through-hole resonators, the first and second resonators being separated by at least one resonator therebetween,

wherein the by-pass electrode plating is elongate and rectangular in shape.

7. A monoblock duplexer filter adapted for connection to an antenna, a transmitter and a river for filtering an incoming signal from the antenna to the receiver and for filtering an outgoing signal from the transmitter to the antenna, the duplexer filter comprising a monolithic, parallelepiped dielectric block having a top, a bottom and four sides, and including:

an antenna electrode pad on the block;

a transmit section extending between the antenna electrode and a first side of the block;

a receive section extending between the antenna electrode and a second side of the block opposing the first end;

each section having a plurality of through-hole resonators, each through-hole resonator extending between the top and the bottom;

a transmit electrode pad on the block and spaced apart from the antenna electrode along the length of the block and positioned in the transmit section;

a receive electrode pad on the block and spaced apart from the antenna electrode along the length of the block and positioned In the receive section;

a first isolated by-pass electrode plating on the block in the transmit section and having portions adjacent to at least three of the plurality of through-hole resonators of the transmit section; and

a second Isolated by-pass electrode plating on the block in the receive section and having portions adjacent to at least three of the plurality of through-hole resonators of the receive section.