A novel frequency doubler using feedforward technique and defected ground structure

A novel design of frequency doubler using feedforward technique and defected ground structure (DGS) is proposed. The feedforward loop in the proposed frequency doubler suppresses the fundamental component (f_o), and the DGS diminishes the higher order harmonics such as third, fourth, and so on. Due to the combination of feedforward structure and DGS, only the doubled frequency component (2f_o) appears at the output port and the other unwanted components are suppressed excellently. A frequency doubler is designed at 1.85GHz of f_o by the proposed technique and measured. The measured output power of 2f_o is -3 dBm when the input power is 0 dBm. The obtained suppression of f_o, 3f_o, and 4f_o are 42.9, 19.2, and 29.7dB, respectively.