efficiency performance both at full output power, as well as, in power back-off operation. The presented theory is verified using a Doherty demonstrator amplifier, ...
A Wide-Band 20W LMOS Doherty Power Amplifier J. H. Qureshi', N. Li', W.e. E. Neo2, F. van Rijs2, I. Blednov2 and L.e.N. de Vreede' I
Abstract constrains
Dirnes, Delft University of Technology, Feldrnannweg 17, the Netherlands 2 NXP RF Power / Basestations, Gerstweg 2, Nijrnegen, the Netherlands
- This work discusses the efficiency bandwidth in
Doherty
amplifiers.
An
analysis
of
devices. Note that optimum wideband operation of the DPA would require the transmission line TL to be a perfect impedance inverter over the whole desired frequency band. Something that without changing the physical properties of the TL is not possible, since the electrical length of the TL increases linearlY �i!p fre.flu.§n.fY..:.
the
bandwidth limitations imposed by the impedance inverter and output capacitance of the active devices is given. Alternative wideband matching and output connection schemes for Doherty amplifiers are evaluated for their efficiency performance both at full output power, as well as , in power back-off operation. The presented theory is verified using a Doherty demonstrator amplifier, which allows independent control of the input signals for the main and
I
Vout
I
�I
peak device. The related measurements show the largest high-efficiency bandwidth reported up to date for a Doherty amplifier.
