PA Output Notch Filter Consideration

1. PA output Notch Filter
Consideration

2. PA output Notch Filter type selection
n F = 433.2 MHz, 2F = 866.4 MHz
n We need to put notch filter at PA output
to enhance 2 order harmonics rejection
n But, series type or shunt type ?

3. PA output Notch Filter type selection
n Series type is better than shunt type in all aspects
IL (dB) Rejection (dB) Impedance
Series Type 0.12 18.86 50.46 + 14.3j
Shunt Type 0.2 16.06 42.83 – 17j

4. PA output Notch Filter type selection
n Series type has three impedance discontinuity, but
shunt type has only one
n Series type has worse impedance discontinuity
(9mil => 20mil) than shunt type(9mil => 12mil)
n Impedance discontinuity effect leads to mismatch loss.
In other words, series type seems to have less loss in
simulation, but actually it has more loss

5. Stub for notch filter ?
n For shunt type, with stub,
there is still impedance discontinuity effect
n In addition, the 2F rejection becomes worse
than the original one due to
the parasitic inductance.

6. Stub for notch filter ?
2fo Rejection (dB)
With Stub 10.44
Without Stub 16.06
Delta 5.6 dB

7. Notch Filter location
n Case A affects PA’s load-pull more than Case B.