Dynamic power supply design for varying envelope signals using envelope tracking method

Abstract

In modern communication systems, demand for higher data-rate is consistently growing. Higher data-rate within a limited bandwidth tends to require more amplitude modulation (AM) to increase number of symbols per second. Amplitude modulated carriers should be amplified using linear power amplifiers (PAs). Although, linear PAs have good performance in terms of linearity, they are efficient only when they transmit at maximum power. However, modern communication signals have high peak-to-average-power ratio (PAPR), therefore probability of a PA transmitting at maximum power is low. As a conclusion, efficiencies are degraded to alarmingly low values and the problem translates to heat and shorter battery life issues. In this thesis, we investigate how dynamic power supplies (DPS) perform for non-constant envelope RF signals. We have designed a DPS and used it to test efficiency enhancement of two PAs compared to the same PAs operating with constant supply. Our aim was to obtain efficiency increase compared to constant supply case without introducing extra non-linearity. We have obtained satisfying results for both amplifiers.