Ultra-Wideband Imaging Systems for Breast Cancer Detection - Ultra-Wideband and 60 GHz Communications for Biomedical Applications - page 100

Fig. 22 Measured a conversion gain, b noise figure with and without the balun, c S 11 , d port to
port isolation, and e IIP3 of the designed mixer
As shown, the gain remains almost constant for various IF frequencies. Also, CG
drops less than 3 dB, when the RF frequency is changed from 3 to 11 GHz. Figure 22 b
shows the noise figure of the designed circuit for both cases of with and without the
balun. As shown, the core mixer (without a balun) has a minimum value of 6.9 dB
and an average of 9.15 dB over the 7.5 GHz bandwidth. Figure 22 c shows the input
reflection coefficient for the RF port which shows excellent matching at this port for
both cases of with and without the balun. Also, Fig. 22 d shows the good performance
of this design in terms of the port to port isolation. Finally, Fig. 22 e provides IIP3 of
the mixer for the whole range of RF frequencies.
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