We have measured the static I-V characteristics of pseudomorphic conventional HEMTs and FETs based on parallel array of quantum wires (UNIFETs) at ambient, 77, and 1.5K, respectively. These measurements show that at ambient temperature the saturation-regime extrinsic transconductance (gm) of the UNIFETs is about 80% higher than that of the conventional HEMTs. The gm
of both types of devices increases as the temperature is lowered. The rate of increase is higher for the UNIFETs due to the one-dimensional character of electron transport. FETs based on array of parallel quantum wires are well-suited for high-frequency applications because of their high transconductance resulting from size quantization and lateral confinement of the carriers.