$E$ -Band Mixer With IP1dB Design Consideration for Radio Astronomical Instrumentation

A lower sideband E-band mixer for radio astronomy is designed with consideration of the power compression. An E-band receiver for astronomy is analyzed to derive the power linearity specification of the mixer. The theory of noise-temperature error due to the power compression is derived. The analysis reveal that receiver with very low noise temperature is much more sensitive to the power saturation. Based on the analysis, the power compression of the mixer is set to less than 2% (0.088 dB), thus the mixer IP
_1dB
should be at least 11 dB higher than the input power to meet the requirement of the receiver with 30-60-K noise temperature. The transistor sizes were explored in the design of the modified cascode mixer to provide sufficient IP
_1dB
and conversion gain. The designed broadband mixer is with IP
_1dB
higher than 3 dBm. This performance is suitable for the E-band astronomical heterodyne receiver applications.