Linearization techniques for amplifiers using MESFETs fabricated with a self-align/selective ion-implantation process

Linearization techniques for amplifiers are proposed and confirmed by experiments. The key is combining a newly developed low-distortion MESFET (LD-FET) with a high-gain depletion-mode MESFET (D-FET), both of which are simultaneously fabricated by a self-align/selective ion-implantation process. The LD-FET is characterized its unique channel doping profile with buried p-type and double n-type ion-implantations. This realizes more constant behavior in terms of mutual conductance (gm) than conventional MESFETs, which is preferable to build linear amplifiers. The combination of two MESFETs with different characteristics realizes multi-stage amplifiers with maximized intercept point (IP3). The obtained third-order intermodulation (IM3) performance of the MAHC amplifier was 8.7 dB better than that the conventional one at the input signal of n˜20 dBm. The result confirms the validity of the proposed techniques