Coupled-resonator on-die filters for WiFi applications

A radio frequency filter circuit for rejecting one or more spurious components of an input signal, the filter circuit comprising:

• a first resonator circuit including a first capacitor and a first coupled inductor pair of a first inductor and a second inductor, the first and second inductors being magnetically coupled with a coupling coefficient of around 0.35 and indirectly electrically connected;
• a second resonator circuit including a second capacitor and a second coupled inductor pair of a third inductor and a fourth inductor, the third and fourth inductors being magnetically coupled with a coupling coefficient of around 0.35 and indirectly electrically connected;
• first and second resonator coupling capacitors each connected to the first resonator circuit and the second resonator circuit;
• a first port connected to at least one of the first resonator circuit and or the second resonator circuit;
• and
• a second port connected to at least one of the first resonator circuit or the second resonator circuit, the input signal being transmitted to one of the first port and the second port, and a filtered signal of the input signal passed through both the first resonator circuit and the second resonator circuit and outputted from the other one of the first port and the second port.

A radio frequency filter circuit for rejecting one or more spurious components of an input signal, the filter circuit comprising:

• a first resonator circuit including a first capacitor and a first coupled inductor pair of a first inductor and a second inductor, the first and second inductors being magnetically coupled and indirectly electrically connected;
• a second resonator circuit including a second capacitor and a second coupled inductor pair of a third inductor and a fourth inductor, the third and fourth inductors being magnetically coupled and indirectly electrically connected, an inductive coupling between the first coupled inductor pair and the second coupled inductor pair being near zero;
• a resonator coupling capacitor connected to the first resonator circuit and the second resonator circuit;
• a first port connected to at least one of the first resonator circuit or the second resonator circuit;
• and
• a second port connected to at least one of the first resonator circuit or the second resonator circuit, the input signal being transmitted to one of the first port and the second port, and a filtered signal of the input signal passed through both the first resonator circuit and the second resonator circuit and outputted from the other one of the first port and the second port.