Phase error free LINC modulator

A new technique for linear amplification with nonlinear components (LINC) is described. LINC implementation is thought to be very difficult because of its sensitivity to phase error caused by the difference in electrical length between two power amplifier branches. The allowable limit of phase error for achieving the 60 dB suppression of the adjacent channel interference (ACI) power is estimated for roll-off bandlimited offset QPSK (OQPSK). Then, a compensating method for this phase error is presented. By using the proposed method, sufficient out-of-band spectrum suppression for mobile radio application is obtained. An output power of 7.5 W and a power efficiency of 21% are experimentally confirmed.