Power amplifier cell

A power amplifier cell comprising:

• a first input terminal configured to receive a first balanced input signal;
• a second input terminal configured to receive a second balanced input signal;
• an output terminal;
• a reference terminal;
• a first power amplifier having:
• a first PA input terminal connected to the first input terminal;
• a first PA output terminal;
• a second power amplifier having:
• a second PA input terminal connected to the second input terminal;
• a second PA output terminal;
• a balun comprising:
• a first balanced node connected to the first PA output terminal;
• a second balanced node connected to the second PA output terminal;
• an unbalanced node connected to the output terminal;
• a first inductor with a first end and a second end, the second end of the first inductor connected to the unbalanced node;
• a second inductor with a first end and a second end, wherein the second inductor is inductively coupled to the first inductor in order to define a first transformer, the first end of the second inductor connected to the first balanced node, and the second end of the second inductor connected to the reference terminal;
• a third inductor with a first end and a second end, wherein the first end of the third inductor is connected to the first end of the first inductor and the second end of the third inductor is connected to the reference terminal;
• a fourth inductor with a first end and a second end, wherein the first end of the fourth inductor is connected to the second balanced node, the fourth inductor is inductively coupled to the third inductor in order to define a second transformer, and the second end of the fourth inductor is connected to the reference terminal;
• a mutual-capacitor having a first terminal and a second terminal, the first terminal of the mutual-capacitor connected to the first end of the first inductor and the first terminal of the mutual-capacitor further connected to the first end of the third inductor, the second terminal of the mutual-capacitor connected to the reference terminal;
• wherein:
• (i) a parasitic capacitance of the first power amplifier;
• (ii) a leakage inductance of the first transformer;
• and (iii) a capacitive coupling between the first inductor and the second inductor, are configured to contribute to a first impedance matching circuit for the first power amplifier;
• and
• (iv) a parasitic capacitance of the second power amplifier;
• (v) a leakage inductance of the second transformer;
• and (vi) a capacitive coupling between the third inductor and the fourth inductor, are configured to contribute to a second impedance matching circuit for the second power amplifier.