HAYASHI and MURAGUCHI : A NOVEL DISTORTION COMPENSATION TECHNIQUE USING AN ACTIVE INDUCTOR

This paper presents a novel d is tor t ion compensation technique using an active inductor. First, we describe the input-reflection-coefficient characteristics of a GaAs MESFET active inductor when input power increases. We show that the inductor exhibits positive amplitude deviation and negative/positive phase deviation as the input power increases when the biases of the FETs are set appropriately. The chip size of the fabricated active inductor is less than 0.52 mm. Then, we show that third-order intermodulation is improved when the active inductor is used as a predistortion linearizer. Third-order intermodulation was improved over the output range from 14 dBm to 25 dBm, and at the output of 15 dBm, third-order intermodulation was improved approximately by 9 dB when the predistortion linearizer was introduced. The active inductor can thus function as a miniaturized predistortion linearizer by using it in the input matching circuit of a power amplifier. This technique can be applied in the miniaturization of wireless communication devices. key words: low, distortion, active, inductance, circuit