Linearity Enhanced Broadband Darlington Power Amplifier IC Using InGaP/GaAs HBT for Handset Modules with FBW of 50%

This letter presents a 0.6–1 GHz broadband Darlington PA using a 2–μm InGaP/GaAs heterojunction bipolar transistor process for mobile application. The Darlington is proposed for high performance broadband PA design, as it improves the product of the gain–bandwidth products of the transistor itself without the problem of reducing the PAE of the circuit. A proposed simple tunable linearization circuit operates as a 2nd harmonic resonance to improve linearity over 0.6–1 GHz frequency band and is designed to adjust the operating frequency differently according to the control voltage of the diode. Using the continuous wave signal, the implemented Darlington PA achieves an output power of 34.3–35.5 dBm, a PAE of 51–61 % based on P3dB and a small-signal gain of 27.2–28.16 dB in a FBW of 50 %. Using the 20 MHz 100 RB BW QPSK LTE signal were obtained ACLR of better than -40dBc at Pout of 27.5-28.5 dBm.