SL869T3-I Product User Guide
1VV0301546 Rev. 3
Page 43 of 68
2021-03-31
2.
Use a quarter wave stub in place of the inductor. The length of the stub is designed
to be exactly ¼ wavelength at L1, which has the effect of making an RF short at
one end of the stub to appear as an RF open at the other end. The RF short is
created by a high-quality RF capacitor operating at self-resonance.
The choice between the two would be determined by:
•
RF path loss introduced either by the inductor or by the quarter wave stub.
•
Cost of the inductor.
•
Space availability for the quarter wave stub.
Simulations done by Telit show the following:
Inductor
Additional signal loss (dB)
Murata LQG15HS27NJ02
0.65
Quarter wave stub on FR4
0.59
Coilcraft B09TJLC (used in ref. design)
0.37
Table 9-1 Inductor Loss
Since this additional loss occurs after the LNA, it is generally not significant unless the
circuit is being designed to work with both active and passive antennas.
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