Miss-Tuned Envelope Injection for 2.1GHz HPA Based on Polynomial Model

A linearization circuitry of miss-tuned envelope injection (MTEI) method is proposed to eliminate intermodulation distortion (IMD) and memory effects of power amplifier (PA). A novel analysis approach using PA polynomial model to analyze its validity is proposed. By injecting both envelope signal and faded two-tones with their IMD products into original two-tone signal, PA's IMD components can be cancelled out, which can overcome the drawback of high power input limit for traditional envelope injection. Two circuitry structures are presented: Direct Envelope Injection (DEI) and Forward Miss-tuned Envelope Injection (FMTEI) structures. Simulation results for 2.1GHz PA show that at 33dBm output, -73dBc and -89dBc third-order IMD suppression (IMD3) can be achieved for DEI and FMTEI respectively, which are 35dB and 51dB better than that without linearization. For FMTEI, amplitude domain compensation for IMD3 shows a broad dynamic output range of 30dBm~50dBm. Frequency domain compensation for IMD3 shows a good memory effects cancellation compared with an RF analog predistorter. The 16-QAM signal application shows 11dB~12dB ACPR improvement with FMTEI.