Identification of frequency dependent memory effects and the linearization of a CMOS PA for multiple standards

This paper presents a method to quantitatively identify memory effects. The accurate determination of characteristic curves for the rising and falling part of demodulated two tone signals provides precise hysteresis loops as a measure of memory effects.The method is applied to a CMOS power amplifier with a maximum peak power of 28 dBm fabricated in a 130nm technology. In the range from 1 kHz to 10MHz several memory effects at different frequencies are extracted. However, dominant effects are visible below 30kHz. The successful linearization of the power amplifier for multiple standards including narrow-band (EDGE) and wideband modulated signals (UMTS,WLAN)is demonstrated.All EVM and ACPR constraints are fulfilled with margin up to the maximum theoretically achievable linear power. The measurement results indicate that wideband modulated signals are less effected by memory effects compared to narrowband modulated signals.