Compact diplexer

• US 7,876,175 B2
• Filed: 11/03/2008
• Issued: 01/25/2011
• Est. Priority Date: 03/28/2008
• Status: Active Grant

• Current Assignee: Ralink Technology Corporation (MediaTek, Inc.)
• Original Assignee: Ralink Technology Corporation (MediaTek, Inc.)
• Inventors: Hsu, Min-Shun
• Primary Examiner(s): Summons; Barbara
• Application Number:
  US12/264,221
• Publication Number:
  US 20090243752A1
• Time in Patent Office: 813 Days
• Field of Search: 333126-129, 333/132, 333/134, 333/136, 455/78, 455/82, 455/552.1, 455/553.1
• US Class Current: 333/126
• CPC Class Codes: H03H 7/38 Impedance-matching networks
• CPC Class Codes: H03H 7/463 Duplexers

Abstract

A diplexer for receiving and transmitting a first bandwidth signal corresponding to a first central frequency and a second bandwidth signal corresponding to a second central frequency includes a first signal end, a second signal end, a third signal end, a first impedance unit, a second impedance unit and a third impedance unit. The first impedance unit forms an impedance match with the third impedance unit when the third signal end receives or transmits the first bandwidth signal, and forms a high impedance unit when the third signal end receives or transmits the second bandwidth signal. The second impedance unit forms an impedance match with the third impedance unit when the third signal end receives or transmits the second bandwidth signal, and forms a high impedance unit when the third signal end receives or transmits the first bandwidth signal.

Claims

1. A diplexer for receiving and transmitting a first bandwidth signal corresponding to a first central frequency and a second bandwidth signal corresponding to a second central frequency, the diplexer comprising:

a first signal end;

a second signal end;

a third signal end for receiving or transmitting the first bandwidth signal and the second bandwidth signal;

a first impedance unit comprising a first end coupled to the first signal end, and a second end, the first impedance unit forming an impedance match with a third impedance unit coupled to the third signal end when the third signal end receives or transmits the first bandwidth signal, and forming a high impedance unit when the third signal end receives or transmits the second bandwidth signal;

a second impedance unit comprising a first end coupled to the second signal end, and a second end, the second impedance unit forming an impedance match with the third impedance unit when the third signal end receives or transmits the second bandwidth signal, and forming a high impedance unit when the third signal end receives or transmits the first bandwidth signal; and

the third impedance unit comprising a first end coupled to the third signal end, and a second end coupled to the second end of the first impedance unit and the second end of the second impedance unit;

wherein the first impedance unit comprises;

a first signal transmission line comprising a first end coupled to the second end of the third impedance unit, and a second end;

a second signal transmission line comprising a first end opened, and a second end; and

a sub impedance unit comprising a first end coupled to the first signal end, and a second end coupled to the second end of the first signal transmission line and the second end of the second signal transmission line;

wherein a length of the first signal transmission line and a length of the second signal transmission line correspond to a quarter of a wavelength corresponding to the second central frequency.

2. The diplexer of claim 1, wherein the second impedance unit is a parallel inductor-capacitor resonant circuit whose resonant frequency corresponds to the first central frequency.

3. The diplexer of claim 1, wherein the first central frequency is 2.4 gigahertz.

4. The diplexer of claim 1, wherein the second central frequency is 5 gigahertz.

5. The diplexer of claim 1 being made on a dielectric substrate made of FR4 fiberglass.

6. A wireless communicator comprising the diplexer of claim 1, wherein the wireless communicator is a wireless access point device, a wireless router, or a wireless network card.

7. A radio frequency (RF) transceiver of a wireless communication device, for receiving and transmitting a first bandwidth signal corresponding to a first central frequency, and a second bandwidth signal corresponding to a second central frequency, the RF transceiver comprising:

an antenna for receiving and transmitting the first bandwidth signal and the second bandwidth signal;

a first RF signal process unit, for processing the first bandwidth signal;

a second RF signal process unit, for processing the second bandwidth signal;

a diplexer coupled to the antenna, the diplexer comprising;

a first signal end;

a second signal end;

a third signal end for receiving or transmitting the first bandwidth signal and the second bandwidth signal;

a first impedance unit comprising a first end coupled to the first signal end, and a second end, the first impedance unit forming an impedance match with a third impedance unit coupled to the third signal end when the third signal end receives or transmits the first bandwidth signal, and forming a high impedance unit when the third signal end receives or transmits the second bandwidth signal;

a second impedance unit comprising a first end coupled to the second signal end, and a second end, the second impedance unit forming an impedance match with the third impedance unit when the third signal end receives or transmits the second bandwidth signal, and forming a high impedance unit when the third signal end receives or transmits the first bandwidth signal; and

the third impedance unit comprising a first end coupled to the antenna and a second end coupled to the second end of the first impedance unit and the second end of the second impedance unit;

wherein the first impedance unit comprises;

a first signal transmission line comprising a first end coupled to the second end of the third impedance unit, and a second end;

a second signal transmission line comprising a first end opened, and a second end; and

a sub impedance unit comprising a first end coupled to the first signal end, and a second end coupled to the second end of the first signal transmission line and the second end of the second signal transmission line;

wherein a length of the first signal transmission line and a length of the second signal transmission line correspond to a quarter of a wavelength corresponding to the second central frequency.

8. The RF transceiver of claim 7, wherein the second impedance unit is a parallel inductor-capacitor resonant circuit whose resonant frequency corresponds to the first central frequency.

9. The RF transceiver of claim 7, wherein the first central frequency is 2.4 gigahertz.

10. The RF transceiver of claim 7, wherein the second central frequency is 5 gigahertz.

11. The RF transceiver of claim 7, wherein the diplexer is made on a dielectric substrate made of FR4 fiberglass.

12. The RF transceiver of claim 7, wherein the wireless communicator is a wireless access point device, a wireless router, or a wireless network card.