Why are Si41xx-BM and Si41xx-BT devices unavailable for order?
Per Process Change Notice #0501071 dated effective 07JAN05, the lead finish version RF Synthesizers were replaced by lead free versions. So for example, P/Ns Si4133-BM and Si4133-BT were replaced by Si4133-D-GM and Si4133-D-GT.
Why is the Si4133W unavailable for order?
The Si4133W RF Synthesizer, i.e. the wide temperature operation version of the Si4133, was sold as a product line by Silicon Labs to NXP as part of the Aerophone technology sale in 2007. NXP then briefly sold it as the Aero4133, discontinuing it at the end of 2008.