An IF CMOS signal component separator chip for LINC transmitters

The LINC transmitter provides linear amplification using highly nonlinear but power efficient amplifiers. The signal component separator (SCS) is a crucial function of LINC. This paper presents an IF SCS chip implemented in a 0.35 /spl mu/m CMOS process using a design based on voltage-translinear circuits. The experimental LINC transmitter, built with the chip and nonlinear amplifiers, had output spurious levels some -55 dBc and -48 dBc for a NADC signal and an IS-95 signal, respectively. This implies a high degree of linearity.