A high-speed buck converter for efficiency enhancement of W-CDMA power amplifiers

Abstract

We present a design strategy for a buck converter, which fulfills the high dynamic requirements of efficient envelope amplifier needed by modern efficiency enhancement techniques for power amplifiers. The proposed DC–DC converter has an innovative control system, which makes it fast, robust, and resource saving. A mathematical model describes its dynamic behavior and is used to find a setup, which gives an optimal compromise between the dynamic performance and efficiency. The approach is applicable to various state-of-the-art communication standards. As an example, an envelope following (EF) power amplifier (PA) for the wideband code-division-multiple-access (W-CDMA) modulation scheme is treated. The corresponding buck converter is implemented in a monolithic chip (except the inductor and the capacitor of the output filter). The measurements with an industry standard W-CDMA PA (RMPA2265) match very well with the forecast of the model and confirm doubling of the average efficiency.

Current Hysteresis Control of High Step-up Current-fed DC-DC Converter for Haptic Application

“…. The pulse-width modulation plus phase angle shift (PPAS) is employed as the drive scheme for four switches, and it is noted that one power switch 1 S (or 3 S ) of each bridge is driven complementarily by the other 2 S (or 4 S ), and the phase difference between two bridges keeps at a constant 180°. Our previous work has proved that this DC-DC converter has the benefits of high gain, low ripple of input current and output voltage, low switching loss, and high conversion efficiency.…”

“…The error voltage  o V works as a feedback quantity in the proposed PWM current hysteresis control scheme, and the error between the theoretical average current of the input inductor 1 L and the reference one can be calculated as (15).…”

“…Due to the symmetry of the circuit, the relationship between the reference current of the input inductor 1 L and 2…”

“…The hysteresis band width will be adjusted according to (12). When the actual current of the input inductor 1 L is larger than the upper threshold, the output signal is in low level and the switch 4 S will turn off. When the actual current of the input inductor 1 L is smaller than the lower threshold, the output signal is in high level and the switch 4 S will turn on.…”

“…As the development of power electronics, various DC-DC converters with high performance have been proposed and applied [1,2]. The steady accuracy of the output voltage waveform is one of the most important output performances of the DC-DC converter, and it is largely determined by the control scheme.…”