X-band doubly balanced resistive FET mixer with very low intermodulation

This paper describes a practical realization of a mixer that achieves low intermodulation distortion by using the channel resistance of a GaAs MESFET to provide mixing and achieves even-order spurious response rejection through the use of a doubly balanced structure. Very good results were achieved in terms of second- and third-harmonic levels of -67 and -45 dBC, respectively, at +10 dBm input level. The band-center conversion loss was 11 dB. The circuit was realized in microstrip on an alumina substrate, with a monolithic FET "quad".>