Multiplexers using weakly-coupled networks in rf front end circuitry

Patent metadata

Field	Value
Publication number	US-2016126922-A1
Application number	US-201514927546-A
Country	US
Kind code	A1
Filing date	Oct 30, 2015
Priority date	Nov 3, 2014
Publication date	May 5, 2016
Grant date	—

Abstract

Multiplexing circuitry is disclosed that includes filtering circuitry, which provides a first transfer function between a common port and a first port and a second transfer function between the common port and a second port. The first transfer function and second transfer function provide a first passband and a second passband, respectively. The first transfer function also has a stopband provided within the second passband of the second transfer function due to the filtering circuitry including a first parallel resonant circuit provided in series in a first filter path being weakly coupled to a second parallel resonant provided in shunt with respect to a second filter path. The weak coupling between the first parallel resonant circuit and the second parallel resonant circuit thus naturally provides a stopband in the first transfer function within the second passband of the second transfer function.

First claim

What is claimed is:

1 . Multiplexing circuitry comprising:
a common port, a first port, and a second port; filtering circuitry coupled to the common port, the first port, and the second port and configured to provide a first transfer function between the common port and the first port and a second transfer function between the common port and the second port wherein:
the first transfer function has a first passband and a first stopband;
the second transfer function has a second passband wherein the first stopband of the first transfer function is within the second passband;
a first parallel resonant circuit is provided in series in a first filter path connected between the common port and the first port; and
a second parallel resonant circuit is provided in shunt with respect to a second filter path that is connected to the second port, wherein the second parallel resonant circuit is weakly coupled to the first parallel resonant circuit such that the first stopband is within the second passband.

2 . The multiplexing circuitry of claim 1 wherein:
the first parallel resonant circuit comprises a first inductor and a first capacitive element connected in parallel; and
the second parallel resonant circuit comprises a second inductor and a second capacitive element wherein the second inductor is coupled in parallel with the second capacitive element.

3 . The multiplexing circuitry of claim 2 wherein the first inductor is magnetically coupled to the second inductor.

4 . The multiplexing circuitry of claim 3 wherein the filtering circuitry further comprises a third capacitive element provided in series within the second filter path and connected to the first filter path so as to electrically couple the first parallel resonant circuit to the second parallel resonant circuit.

5 . The multiplexing circuitry of claim 1 wherein the filtering circuitry further comprises a capacitive element connected between the first parallel resonant circuit and the second parallel resonant circuit so as to electrically couple the first parallel resonant circuit to the second parallel resonant circuit.

6 . The multiplexing circuitry of claim 1 wherein:
the first parallel resonant circuit is configured to resonate at a first frequency within the second passband; and
the second parallel resonant circuit is tunable to resonate at a second frequency within the second passband.

7 . The multiplexing circuitry of claim 1 wherein the second filter path is coupled capacitively to the first filter path.

8 . The multiplexing circuitry of claim 1 wherein the second filter path is coupled magnetically to the first filter path.

9 . The multiplexing circuitry of claim 1 wherein the filtering circuitry further comprises a first matching network provided within the first filter path and connected to the first port, wherein the first matching network is tunable so as to match a port impedance of the first port to a filter path impedance of the first filter path.

10 . The multiplexing circuitry of claim 1 wherein the filtering circuitry further comprises a series resonant circuit provided in series within the first filter path between the common port and the first parallel resonant circuit wherein the series resonant circuit is configured to resonate at a frequency within the first passband.

11 . The multiplexing circuitry of claim 1 wherein the filtering circuitry further comprises a variable capacitive element having a variable capacitance and wherein:
the variable capacitive element is provided in series within the second filter path and is connected to the second port; and
the variable capacitive element is tunable so as to match a port impedance of the second port with a path impedance of the second filter path.

12 . The multiplexing circuitry of claim 1 further comprising a third port wherein the filtering circuitry further comprises a third filter path connected to the third port wherein the filtering circuitry is further configured to provide a third transfer function between the common port and the third port and the third filter path is configured to provide a third passband in the third transfer function.

13 . The multiplexing circuitry of claim 12 wherein the second parallel resonant circuit is weakly coupled to the first parallel resonant circuit such that the third transfer function defines a second stopband within the second passband.

14 . The multiplexing circuitry of claim 13 wherein the filtering circuitry comprises a common path connected between the common port and a connection node wherein:
the first filter path branches from the common path so as to extend from the connection node to the first port; and
the third filter path branches from the common path so as to extend from the connection node to the third port.

15 . The multiplexing circuitry of claim 14 further comprising a fourth port wherein the filtering circuitry is coupled to the fourth port so as to provide a fourth transfer function between the common port and the fourth port and wherein:
the fourth transfer function has a fourth passband;
a third parallel resonant circuit is provided in series in the common path; and
a fourth parallel resonant circuit is provided in shunt with respect to a fourth filter path that is connected to the fourth port, wherein the fourth parallel resonant circuit is weakly coupled to the third parallel resonant circuit such that the first transfer function defines a third stopband within the fourth passband and the third transfer function defines a fourth stopband within the fourth passband.

16 . The multiplexing circuitry of claim 14 further comprising a fourth port wherein the filtering circuitry is coupled to the fourth port so as to provide a fourth transfer function between the common port and the fourth port and wherein:
the fourth transfer function has a fourth passband;
a third parallel resonant circuit is provided in series in the third filter path;
a fourth parallel resonant circuit is provided in shunt with respect to a fourth filter path that is connected to the fourth port, wherein the fourth parallel resonant circuit is weakly coupled to the third parallel resonant circuit such that the first transfer function defines a third stopband within the fourth passband and the third transfer function defines a fourth stopband within the fourth passband.

17 . The multiplexing circuitry of claim 13 further comprising a fourth port wherein the filtering circuitry is coupled to the fourth port so as to provide a fourth transfer function between the common port and the fourth port and wherein:
the fourth transfer function has a fourth passband;
a third parallel resonant circuit is provided in series in the first filter path;
a fourth parallel resonant circuit is provided in shunt with respect to a fourth filter path that is connected to the fourth port, wherein the fourth parallel resonant circuit is weakly coupled to the third parallel resonant circuit such that the first transfer function defines a third stopband within the fourth passband and the third transfer function defines a fourth stopband within the fourth passband.

18 . The multiplexing circuitry of claim 1 further comprising a third port wherein:
the filtering circuitry is coupled to the third port to provide a third transfer function between the common port and the third port such that the third transfer function defines a third passband;
the filtering circuitry comprises a common path connected between the common port and a connection node wherein:

Assignees

• Rf Micro Devices Inc

Inventors

• Leipold Dirk Robert Walter
• Maxim George
• Scott Baker

Classifications

• H01F2027/2809

  on stacked layers · CPC title

• H03H7/38

  Impedance-matching networks · CPC title

• H01F27/2804 Primary

  Printed windings · CPC title

• H04J1/08

  Arrangements for combining channels {(branching filters H01P1/213, H03H7/46)} · CPC title

• H04B1/40

  Circuits · CPC title