A voltage-translinear based CMOS signal component separator chip for linear LINC transmitters

The LINC transmitter is an architecture that provides linear amplification using nonlinear but power efficient amplifiers. One crucial signal processi ng function of LINC is the signal component separator (SCS) which forms two constant-amplitude phase-modulated signals from the source signal. This pa per presents an analog SCS chip implemented in a 0.35 mum CMOS process usin g a novel design based on the so-called voltage-translinear circuit princip le. An experimental LINC transmitter was built with the SCS chip, nonlinear amplifiers and a power combiner. Test results showed that all output spuri ous levels some -55 dBc and -48 dBc could be obtained with a North American Digital Cellular (NADC) signal and an IS-95 signal, respectively. This imp lies a high degree of linearity.