Efficienc Enhancement - Linear CMOS RF Power Amplifiers for Wireless Applications - page 13

Table 2.1 Summary of the main performance metrics of works on efficiency-enhanced PAs

Reference [ 32 ] [ 23 ] [ 2 ] [ 12 ] [ 27 ] [ 33 ] [ 35 ]

Year 1998 2005 1995 1999 2004 2004 2006

Technique EER EER Dyn. Dyn. Dyn. Dyn. Switched

Dyn.

Technol. PA CMOS CMOS Discr. GaAs Discr.

Bip.

Discr.
GaAs

Discr.
Bip.

Technol. Mod. CMOS CMOS Discr.

GaAs

GaAs CMOS Discr.

MOS

Discr.
MOS

Supply (V) 3 3.3 - 3.6 3.3 6 5.5

f c (GHz) 0.835 1.75 4 0.95 1.9 2.4 2.4

P out (dBm) 28 23.8 36 20 20.5 15.1 19

PAE (%) 33 22 11.7 14 32 25 28

ACPR (dBc) - - - − 26 − 45 - -

EVM (%) 3.4 1.7 - - 4.9 3.2 2.8

IMD3 (dBc) - - − 50 - − 30 - -

Mod. Eff. (%) 80 - - 74 85 75 60

f s (MHz) - - - 10 16 7 6

Linearization - DPD - - - DPD DPD

Application NADC EDGE TCM CDMA CDMA WLAN WLAN

Note: Technol. = Technology; Mod. = Modulator; Eff. = Efficiency; Discr. = Discrete;

Bip. = Bipolar

2.3.2.3 Dynamic Supply with Switched-Mode PA

Wang et al. in [ 35 ] call their system hybrid EER because the signal at the input of
the PA is still a complex-modulated signal (like in the dynamic supply PA) and the
PA operates in switched-mode (like in EER). However, there is neither elimination
nor restoration of the envelope and, hence, the name EER for this technique is also
a misnomer. As it was stated previously, the dynamic supply technique requires
a linear PA so that the maximum distortion constraints can be respected. Hence,
in [ 35 ], the authors used predistortion in order to circumvent the inherent distortion
problems. An important contribution from their work, however, was the detailed
description of the implementation of a split-band modulator. This modulator solved
the problem of limited bandwidth by using a linear regulator to provide the dynamic
supply when the envelope frequency is high and a buck converter to provide the
dynamic supply when the envelope frequency is low. The system presented a PAE
of 28% and an EVM of 2.8% at an output power of 19 dBm (80 mW). The same
split-band modulator was also used in [ 20 , 33 , 34 , 36 ].