Investigation of LO-leakage cancellation and DC-offset influence on flicker-noise in X-band mixers

This paper describes an investigation on the influences in 1/f noise of LO-leakage and DC-offset cancellation for X-band mixers. Conditions for LO-leakage cancellation and zero DC-offset is derived. Measurements on a double balanced diode mixer shows an improvement in noise figure from 14.3 dB to 12.1 dB at 10 KHz, while maintaining a noise figure of 6.2 dB at 1 MHz. LO-RF isolation is improved from 18 dB to 60 dB. The 1/f noise is shown to increase with increasing DC-offset.