Patent ID: 8354882

Claim:
An electronic circuit comprising a Doherty amplifier for use in a frequency band, wherein the Doherty amplifier comprises: an input operative to receive an input signal; an output operative to supply an output signal; a main device interposed between the input and the output; a peak device interposed between the input and the output; and an input combiner connecting the input to an input node of the main device and to an input node of the peak device, the input combiner comprising a first branch between the input and the input node of the main device so as to implement a first frequency-dependent input impedance with a first real part and a first imaginary part as considered from the input node; and a second branch between the input and the input node of the peak device so as to implement a second frequency-dependent input impedance with a second real part and a second imaginary part as considered from the input node; wherein the first and second imaginary parts have opposite polarity; wherein the first and second imaginary parts have substantially a same magnitude so as to substantially compensate each other in the frequency band; wherein the first imaginary part and the second imaginary part implement a first phase shift in the first branch and a second phase shift in the second branch, respectively; and wherein each of the first and second phase shifts varies with frequency over the frequency band, but has opposite polarity and similar magnitude, thus mitigating frequency-dependent variations in input impedance at the main and peak devices; and wherein each of the first and second phase shifts has a magnitude of substantially 45 degrees substantially in the middle of the frequency band.