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An approach for matching the transconductance characteristics of CMOS ion-sensitive field-effect transistor (ISFET) arrays is discussed. The ISFET array is found to have a measured sensitivity of 46 mV/pH after matching.

The voltage-current characteristic of a four-terminal mesoscopic cross is grossly nonlinear, indicating two clear regions of negative differential resistance (NDR). The device takes advantage of a planar GaAs technology. One of the NDR regions was utilized to perform frequency conversion. Findings indicated efficient frequency doubling at low frequency. Asynchronous and heterodyne amplitude modulation were obtained at 5 MHz radio frequency.

We present the cofabrication of planar Gunn diodes and high-electron mobility transistors (HEMTs) on an indium phosphide substrate for the first time. Electron beam lithography has been used extensively for the complete fabrication procedure and a 70-nm T-gate technology was incorporated for the enhancement of the small-signal characteristics of the HEMT. Diodes with anode-to-cathode separation ( \(L_{\rm ac}\) ) down to 1- and 120- \(\mu \) m width were shown to oscillate up to 204 GHz. The transistor presents a cutoff frequency ( \(f_{_{T}}\) ) of 220 GHz, with power gain up to 330 GHz ( \(f_{\max }\) ). The integration of the two devices creates the potential for the realization of high-power, high-frequency MMIC Gunn oscillators, circuits, and systems. [ABSTRACT FROM AUTHOR]