Broadband Tunable Third-Order IMD Cancellation Using Left-Handed Transmission-Line-Based Phase Shifter

We demonstrate a broadband tunable third-order intermodulation distortion (IMD) cancellation architecture using a left-handed transmission line (LHTL)-based phase shifter for a feedforward amplifier. The fabricated circuit reduces the third-order IMD of the main amplifier up to 17 dB after adjusting for any frequencies between 1.5 and 2.4 GHz when the frequency difference between the two tones is 2 MHz. In addition, the circuit maintains a spurious-free dynamic range that is greater than 55 dBc at the output. This effective broadband third-order IMD cancellation method is possible because of the broadband and linearly phase-tunable characteristics of the LHTL-based phase shifter.