I have a chip which needs a quadrature LO. Specifications:
- Frequency range: 1.7 GHz - 2.5 GHz (wider range appreciated)
- Both I/Q differential (i.e. 4 wires in total)
- Each wire 1Vpp
- DC offset of 500mV (capable of driving 50 Ohm, i.e., 10-20mA)
- Matching is 50 Ohm but not perfect (S11 > -10dB)
- Jitter: hundreds of fs rms (like 400fs)
- Phase accuracy: ~1 deg
- If possible: Capability of fast (or even ultra fast) hopping/settling (around 10ns)
- Cost: "does not matter"
- Power: "does not matter"
For my current revision, I use an external signal generator which goes into a 90 Degree hybrid and enters the PCB via 2 SMA connectors (I and Q). Each of these channels go through an on-board 1:1 balun. An RF choke adds DC offset of 500mV.
However, this setup is clunky, the on-board balun (MABA-007871-CT1A40) does not even meet the specs. For my second revision, I would like to generate these signals on-board to simplify the setup.
An RFDAC (like AD9164: 16 Bit, 12 GPBS) would satisfy all requirements but getting this 165-pin BGA beast with its SERDES interface working takes me forever.
So if I relax the fast settling requirement I would assume there are solutions out there. However, I am unable to find any quadrature generators on DigiKey! (I can find I/Q Modulators or Demodulators but I need the generation).