Si4212

The Aero® IIe transceiver Si4212 is a complete RF front end for multi-band GSM, GPRS, and EDGE wireless communications. The receive section interfaces between the RF band-select SAW filters and the baseband processor. The transmit section interfaces between the baseband processor and the power amplifier and uses a unique dual-transmitter architecture for EDGE. In GMSK mode, the offset phase locked loop (OPLL) is modulated by the I and Q signals. In 8-PSK mode, the OPLL is unmodulated and acts as a local oscillator (LO) to the direct upconversion mixer. All functions of Si4212 traditionally performed by sensitive components such as VCOs, loop filters, tuning inductors, and varactors are integrated into the integrated circuit (IC). The Aero IIe transceiver includes a digitally-controlled crystal oscillator (DCXO) and completely integrates the reference oscillator and varactor functions. The Aero IIe digital low-IF Si4212 receiver architecture provides inherent suppression of dc offsets, preventing the need for dc offset compensation, manufacturing calibration, or related baseband support.