RF Power Amplifier, 2nd Edition

3.4 Push–Pull Complementary Class AB, B, and C RF Power Amplifiers

3.4.1 Circuit of Push–Pull RF Power Amplifier

A circuit of push–pull Class AB, B, or C RF power amplifiers is shown in Fig. 3.22. It consists of complementary pair of transistors (NMOS and PMOS), parallel-resonant circuit, and coupling capacitor . The transistors should have matched characteristics and are operated as voltage-dependent current sources. Since complementary transistors are used, the circuit is called a complementary push–pull amplifier or a complementary-symmetry push–pull amplifier. If MOSFETs are used, the circuit is called a push–pull power amplifier. The circuit may also employ complementary bipolar junction transistors (CBJT): an transistor and a transistor. A Class B push–pull amplifier uses one transistor to amplify the positive portion of the input voltage and another transistor to amplify the negative portion of the input voltage. The coupling capacitor blocks the dc voltage from the load. It also maintains the dc voltage and supplies the PMOS transistor when the NMOS transistor is not conducting. ...