Modulation of low-frequencyoscillations in GaAs MESFETs’ channel current by sidegating bias

Low-frequency oscillations in channel current are usually observed when measuring the GaAs MESFET’s output characteristics. This paper studies the oscillations by testing the MESFET’s output characteristics under different sidegate bias conditions. It is shown that the low-frequency oscillations of channel current are directly related to the sidegate bias. In other words, the sidegate bias can modulate the oscillations. Whether the sidegate bias varies positively or negatively, there will inevitably be a threshold voltage after which the low-frequency oscillations disappear. The observa- tion is strongly dependent upon the peculiarities of chan- nel-substrate (C-S) junction and impact ionization of traps-EL2 under high field. This conclusion is of particular pertinence to the design of low-noise GaAs IC’s.