Resistive MOSFET mixer for mobile direct conversion receivers

A double balanced resistive MOSFET mixer developed for mobile communication terminals of the forth generation will be presented in this paper. Receivers of such systems have to be compatible to different standards and different down-conversion methods with the same hardware. Hence, it can be used also as IQ demodulator for RF and IF signals, depending on the front-end architecture used. RF and IF frequency ranges are 2-3 GHz and DC to 50 MHz, respectively. The mixer consumes no DC power, has low LO power consumption, a high linearity, and low RF noise. No 1/f- noise could be detected in the IFfrequency range down to 10 kHz. A conversion loss of 6 to 6.5 dB has been achieved. Measured linearity values are +7 dBm for 1dB power compression and 16.5 dBm for third order intercept point. All isolation values are typically higher than 45 dB between all ports. The circuit was simulated using ADS from Agilent and the layout work has been carried out in Cadence. We will discuss the design flow in this paper and present a comparison of simulated and measured results. In comparison with reported results on 0.35 μm MOSFET mixers, we will show that the measured mixer data are excellent regarding the low-frequency noise, DC power consumption, linearity, bandwidth and isolation. The complete set of features makes this mixer type a well suitable candidate for 4G mobile communication receivers.