please give me some advice on how to design VCO buffer.i desined a 4~8GHz VCO without buffer desined in 2um HBT process.,it works well,but I need a 4~8GHz VCO buffer.is a attenuator needed? i don't think insert a attenuator between VCO and the buffer is a good idea in MMIC,is that wright? why so many VCO papers never discuss VCO buffer? thanks.
The choice of to add a buffer amp or not depends on two things:
1) If you need higher power (> perhaps 5 dBm), you will need the buffer amp.
2) If the impedance of the load changes, like in a sp2t switch going to two locations, then the VCO will jump in frequency/phase, and if you can not take the jump, then you will need isolation. The amount of isolation will dictate how many buffer amplifier stages and attenuator pads are needed.
please give me some advice on how to design VCO buffer.i desined a 4~8GHz VCO without buffer desined in 2um HBT process.,it works well,but I need a 4~8GHz VCO buffer.is a attenuator needed? i don't think insert a attenuator between VCO and the buffer is a good idea in MMIC,is that wright? why so many VCO papers never discuss VCO buffer? thanks.