Integrated doherty type amplifier arrangement with high power efficiency
View Patent ↗The present invention relates to an integrated Doherty type amplifier arrangement and an amplifying method for such an arrangement, wherein a lumped element hybrid power divider ( 12 ) is provided for splitting input signals of main and peak amplifier stages ( 20, 30, 40 ) at predetermined phase shifts and non-equal division rates and at least one wideband lumped element artificial line (Z 1 , Z 2 ) combined with wideband compensation circuit for receiving said first amplified signal and for applying said predetermined phase shift to said first amplified signal and its higher harmonics. Thereby, the low gain of the peak amplifier is compensated by providing the non-equal power splitting at the input. Moreover, the use of the lumped element hybrid power divider leads to an improved isolation between the input ports of the main and peak amplifiers decreasing final distortions of the output signal.
1. An integrated Doherty type amplifier arrangement, comprising:
a) a main amplifier stage for receiving a first signal and for amplifying the first signal to generate a first amplified signal;
b) at least one peak amplifier stage for receiving at least one respective second signal, said peak amplifier stage being arranged to start operation when the level of that respective second signal has reached a predetermined threshold;
c) at least one lumped element hybrid power divider means for splitting an input signal of said amplifier arrangement into said first and at least one second signals at predetermined phase shifts and at non-equal division rates; and
d) at least one lumped element artificial line for receiving said first amplified signal and for applying said predetermined phase shift to said first amplified signal.
2. An amplifier arrangement according to claim 1 , wherein said main and peak amplifier stages comprise at least one of bipolar elements, metal oxide semiconductors, LDMOST elements, field effect transistors, and HBT elements.
3. An amplifier arrangement according to claim 1 wherein said lumped element hybrid power divider means are built with bond wires or deposited inductances and capacitances.
4. An amplifier arrangement according to claim 1 , wherein said main amplifier and peak amplifier stages comprise an output compensation circuit for compensating a parasitic output capacitance at fundamental frequency and least one odd multiple thereof.
5. An amplifier arrangement according to claim 4 , wherein said output compensation circuit is adapted to provide a substantially reduced impedance at a frequency of at least one even multiple of said fundamental frequency.
6. An amplifier arrangement according to claim 4 , wherein said output compensation circuit comprises two inductors and two capacitors or their equivalents.
7. An amplifier arrangement according to claim 6 , wherein said inductors of said output compensation circuit are made at least partly of bond wires.
8. An amplifier arrangement according to claim 1 , wherein said main and at least one peak amplifier stages are connected at their outputs via said lumped element artificial line which acts as a quarter wave length transmission line.
9. An amplifier arrangement according to claim 1 , wherein said lumped element artificial line comprises two or more inductively coupled wires and one or more capacitors connected with its one end to a common point of two of said inductively coupled wires and with its other end to a reference potential.
10. An amplifier arrangement according to claim 1 , wherein said lumped element hybrid power divider means is arranged to provide isolation between all ports at arbitrary power division and two substantially maintain said predetermined phase shift between said first and at least one second signal over a wide frequency range.
11. An amplifier arrangement according to claim 10 , wherein said lumped element hybrid power divider means comprises at each input port a respective serial inductor and two first parallel capacitors connected to each other at their one ends via said serial inductor and connected at their other ends to a reference potential, and two second parallel capacitors respectively connecting the ends of said respective serial inductors.