PA for BPSK and O-QPSK modulation?
Is there any 1W PA MMIC in 900MHZ for this modulation?
O-QPSK is a constant amplitude waveform, so no special requiriments for linearity what means that you can drive the PA into the saturation.
For BPSK, which is basically a AM-DSBSC you can drive the PA to a IMD-3 between 30 and 40dBc.
You should be able to find some gain block able to put 1W out for the waveforms you are loking forward from RF Microdevices or Sirenza. Freesacale also has some LDMOS for 900MHz operation.
NandoPG
You can really have much worse linearity than -30 dBc IMD3 with BPSK/QPSK without affecting BER. The information is in the phase so even with high spectral-regrowth the demodulation is not affected until it really get's bad. The main requirement for linearity is to minimize adjacent channel interference, so if you don't care about that then you can have poor linearity and still get good BER.
An IMD3 worst than -30dBc indeed does not impact the BER very much, but by the other hand is hard to find a system specification allowing an outband emission much worse than -30dBc respect to the Carrier Peak Power.
As normally one is interested in transmitting the information, 30dB is a kind of system limit.
Even in multicarrier systems an outband shoulder higher than -30dBc is not allowed, what makes the PA's design for this kind of waveform very tricky.
NandoPG