US 12,407,320 B2
Bridge filters
Edgar Schmidhammer, Stein an der Traun (DE); and Juha Sakari Ella, Salo (FI)
Assigned to RF360 Singapore Pte. Ltd., Republic Plaza (SG)
Filed by RF360 SINGAPORE PTE. LTD., Singapore (SG)
Filed on Apr. 28, 2022, as Appl. No. 17/661,197.
Prior Publication US 2023/0353117 A1, Nov. 2, 2023
Int. Cl. H03H 7/42 (2006.01); H03H 7/01 (2006.01); H03H 7/38 (2006.01); H03H 9/205 (2006.01); H04B 1/40 (2015.01)
CPC H03H 7/42 (2013.01) [H03H 7/0138 (2013.01); H03H 7/38 (2013.01); H03H 9/205 (2013.01); H04B 1/40 (2013.01)] 18 Claims
OG exemplary drawing
 
1. An apparatus comprising:
a filter circuit comprising:
a first current balun comprising:
a first terminal, a second terminal, a third terminal, and a fourth terminal, the first terminal coupled to a first port of the filter circuit, the third terminal coupled to a ground;
a first inductor galvanically coupled between the first terminal and the second terminal; and
a second inductor galvanically coupled between the third terminal and the fourth terminal;
a filter core coupled between the first current balun and a second port of the filter circuit, the filter core galvanically coupled to the second terminal of the first current balun and to the fourth terminal of the first current balun, the filter core comprising: a first resonator coupled between the second terminal of the first current balun and a first node; a second resonator coupled between the fourth terminal of the first current balun and a second node; a third resonator coupled between the second terminal of the first current balun and the second node; and a fourth resonator coupled between the fourth terminal of the first current balun and the first node;
a second current balun comprising:
a first terminal coupled to the second port, a second terminal, a third terminal coupled to a ground, and a fourth terminal, the second terminal of the second current balun is coupled to the second node, and the fourth terminal of the second current balun is coupled to the first node;
a first inductor galvanically coupled between the first terminal of the second current balun and the second terminal of the second current balun; and
a second inductor galvanically coupled between the third terminal of the second current balun and the fourth terminal of the second current balun;
an inductor coupled between the second terminal of the first current balun and the fourth terminal of the first current balun; and
another inductor coupled between the second terminal of the second current balun and the fourth terminal of the second current balun;
a resonant circuit coupled between the second terminal of the first current balun and a ground, the resonant circuit comprising:
an inductor; and
a capacitor coupled in parallel with the inductor between the second terminal of the first current balun and the ground; and
a matching network coupled between the first port and the first current balun.