Ninety degree coupler for radio frequency degraded circuits
View Patent ↗The present invention provides a ninety degree coupler for a frequency range of 100 mHz to gigaHertz ranges and including a minimum number of components employing a four port device which receives an input signal and splits it between a transformer coil and another reactor and couples it to another port and splits it between the transformer and a capacitor, then cross-connecting to a capacitor where phase shift is created by the inductors and capacitors resulting in phase shift between the signal ports remaining at 90 degrees over a wide frequency band.
1. A four port coupling device comprising a 90 degree phase shifter having ports 1 , 2 , 3 , and 4 , port 1 for receiving an input signal, and having an output appearing across ports 2 and 3 and the input appearing across ports 1 and 4 ,
a transmission line capacitor coupled between each port and ground,
a first transformer having a first winding connected between ports 1 and 2 and a second winding connected between ports 3 and 4 , said first and second windings being coupled in phase, a second transformer having a first winding connected across port 1 and port 4 sides of said first and second windings of said first transformer respectively, a second winding connected across port 2 and port 3 sides of the first and second windings of said first transformer respectively, said windings of said second transformer being coupled in phase.
2. The coupling device of claim 1 wherein the windings of said first and second transformers respectively are closely coupled.
3. The coupling device of claim 2 wherein each winding of the first transformer has an inductance of 33.5 nH, each winding of the second transistor has a value of 47.5 nH and said capacitors each have a capacitance of 45 pF, whereby phases of substantially 90° and 180° respectively are provided at ports 2 and 3 at an input frequency of 170 mHz.
4. The coupling device of claim 2 wherein each winding of the second transformer has an inductance of 2.8 nH, each winding of the second transistor has a value of 3.9 nH and said capacitors each have a capacitance of 3.9 pF, whereby phases of substantially 900° and 180° respectively are provided at ports 2 and 3 at an input frequency of 2 GHz.