Monolithic supply modulated RF power amplifier and DC-DC power converter IC

Abstract

Mobile communication systems require highly efficient, linear, and integrated power amplifiers. This paper reports the results of a monolithic envelope following system implemented .in a 0.18pn SiCe BiCMOS process technology. The monolithic envelope following system consists of a synchronous buck DC-DC converter, which is integrated with and provides the, power supply for a 900 MHz power amplifier while tracking the envelope of the RF input signal.

Survey of architectures and optimizations for wide bandwidth envelope amplifier

“…Single input single output converter As it has been said before, a switching dc-dc converter offers high efficiency and in the state of the art there can be found many solutions based on a buck converter due to its simplicity. Buck converter is a very attractive solution when it is necessary to implement a solution for an integrated PA [7][8][9]. These solutions operate at extremely high switching frequencies (up to 200MHz) in order to minimize the size of passive components and facilitate the integration.…”

Power Amplifier Principles and Modern Design Techniques

“…The PAR of the uplink signal containing a single channel is smaller and the handset PA design seems easier by comparison, but is no small feat in absolute terms. It is not surprising that the CDMA PA design problem has generated a large amount of activities and ideas [33][34][35][36][37][38][39][40]. The most successful CDMA PA approach to date is class AB with efficiency enhancements, but other techniques are also considered.…”

“…Agile DC-to-DC converters with over 90% efficiency capable of adjusting the PA output power by 1dB every 1.2 ms as required in CDMA are readily available [31,32]. Further activities are reported in stand-alone agile DC-to-DC converters [33][34][35] as well as DC-to-DC converters cointegrated with class AB PAs [36].…”

Envelope Following-Based RF Transmitters Using Switching-Mode Power Amplifiers

“…3(b) can be expressed as (1) where is the voltage error to account for the deviation from the linear part that corresponds to the targeted 12-dB constant gain. From (1), can be compensated for by designing a digital predistorter to modify as (2) It is noted that is a smoothly varying function and can be curve-fitted as a polynomial for the purpose of implementing the predistorter as a digital arithmetic unit. In a digital modulation test, can be regarded as equal to the transient envelope of the applied quadrature-modulated signal.…”

“…The high peak-to-average power ratio (PAPR) in these modulation schemes usually requires a highly linear power amplifier (PA) with a sacrifice in efficiency. The envelope-following techniques in [1] and [2] can improve the linear PA's average efficiency by amplitude-modulating the supply voltage at the rate of the envelope variation via a Classmodulator. This can let the supply voltage vary positively with the envelope level so as to save average dc power consumption.…”