Silicon MESFETs for improved VHF and UHF mixer performance

Silicon MESFET devices were evaluated for their potential to improve conventional VHF and UHF communication systems based on reported high frequency capabilities and theoretical square law operation. MESFET and MOSFET discrete devices of the same geometry were tested in RF circuits to compare performance. The MESFET devices were clearly superior to the MOSFET devices at VHF and UHF frequencies in terms of noise figure, gain bandwidth product, and range of square law operation. An experimental TV receiver was constructed with silicon MESFET devices for several functions. One double balanced MESFET mixer was used for both VHF and UHF bands. The mixer had +2 db of conversion gain and could handle two + 4 dBm signals with -40 db third order intermodulation products.