Sinusoidal frequency tripler using fundamental-rejecting feedback

The author presents a sinusoidal frequency tripling circuit which uses an operational transconductance amplifier (OTA) to distort the input signal and generate odd harmonics. By means of a feedback loop that rejects the fundamental of the distorted signal, the circuit produces an output signal whose frequency is three times the input frequency, and can accommodate input signals of different amplitudes. The distortion of the output signal is low for input amplitudes within a reasonably wide range. The response and stability of the circuit are discussed, and experimental results are provided