Amplifier and wireless communication device

A wireless communication device, comprising:

• a signal processing circuit configured to convert a digital signal included transmission data into an analog signal whose frequency is higher than a frequency of the digital signal;
• and
• an amplifier configured to amplify and output the analog signal converted by the signal processing circuit,
• wherein the amplifier includes:
• a first amplifier circuit unit configured to output a signal having a maximum output power of the amplifier;
• and
• a second amplifier circuit unit provided in parallel with the first amplifier circuit unit between an input and an output of the amplifier and having a higher amplification efficiency than the first amplifier circuit unit in an output power lower than an output power of the first amplifier circuit unit,
• wherein, when one of the first amplifier circuit unit and the second amplifier circuit unit is in an operating state in which power amplification of a signal is performed, the other of the first amplifier circuit unit and the second amplifier circuit unit is in a non-operating state in which power amplification of the signal is not performed,
• wherein the first amplifier circuit unit includes:
• a first transistor whose drain is coupled to a first output node of the first amplifier circuit unit;
• a second transistor whose drain is coupled to a second output node of the first amplifier circuit unit;
• and
• a cross-coupled capacitor provided between the drain of one of the first transistor and the second transistor and a gate of the other of the first transistor and the second transistor, and
• wherein the second amplifier circuit unit includes:
• a first capacitor;
• a third transistor whose drain is coupled to an output node of the second amplifier circuit unit via the first capacitor;
• a first inductor coupled to a drain of the third transistor;
• and
• a series circuit in which a first switch and a second capacitor are coupled in series between the drain of the third transistor and a ground, the first switch being in a conducting state when the first amplifier circuit unit is in the operating state and being in a non-conducting state when the second amplifier circuit unit is in the operating state.