How to make output matching wider?
时间:04-05
整理:3721RD
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Hi to all,
Currently, I'm designing simple LNA IC, which will work at 1565 - 1630 MHz frequency band. All with it is ok, except output matching - S22 has approximately 125 MHz bandwidth at level -10 dB.
This is first matching circuit which i have used:
The circuit is quite good, but value of series capacitor is very small and with corners and mismatches i'll get big changes in output matching.
Another circuit, that i have tried, is simple series inductance at output: with load LC network i can reach real 50 Ohm and with series inductance i cancel image part.
Both circuit have narrow bandwidth. Could you give me advice about the way to get wider output matching (target value ~ 200 MHz) ?
PS. I already tried to connect resistor in parallel with load inductor and lowering Q. This works, but cost for additional 20 MHz extension is -3 dB in a gain.
PPS. I can't place additional inductors - there are not enough space on chip :)
Thanks in advance.
Currently, I'm designing simple LNA IC, which will work at 1565 - 1630 MHz frequency band. All with it is ok, except output matching - S22 has approximately 125 MHz bandwidth at level -10 dB.
This is first matching circuit which i have used:
The circuit is quite good, but value of series capacitor is very small and with corners and mismatches i'll get big changes in output matching.
Another circuit, that i have tried, is simple series inductance at output: with load LC network i can reach real 50 Ohm and with series inductance i cancel image part.
Both circuit have narrow bandwidth. Could you give me advice about the way to get wider output matching (target value ~ 200 MHz) ?
PS. I already tried to connect resistor in parallel with load inductor and lowering Q. This works, but cost for additional 20 MHz extension is -3 dB in a gain.
PPS. I can't place additional inductors - there are not enough space on chip :)
Thanks in advance.
Use a Pi match (two caps, and one inductor) which will give wider BW. Increasing the number of poles of the Pi network would increase the BW even further.