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Figures 9 and 10 provide simulation results of the mixer’s input third-order-intercept-point (IIP3) performance. At a RF of 7.5 GHz, two-tone signals with a frequency spacing of 10 MHz and equal power levels of -30 dBm are applied to the downconversion mixer, with a maximum IIP3 of +6.84 dBm (per Fig. 7). With 0-dBm fixed LO power, the measured IIP3 varies from +1.0 to +6.84 dBm when the RF rises from 1.5 to 11.5 GHz (Fig. 10). The power dissipation is 0.46 mW at a +0.75-VDC supply voltage.

Design A Low-Voltage UWB CMOS Mixer, Fig. 9

Design A Low-Voltage UWB CMOS Mixer, Fig. 10

Figure 11 shows a layout for the downconversion mixer, which occupies a chip area of only 0.36 x 0.32 mm2. The table offers a comparison of the mixer’s performance with recently published results. The new mixer structure provides respectable linearity, conversion gain, and acceptable noise performance with low LO power and less power dissipation compared to other recent mixer designs. 

Design A Low-Voltage UWB CMOS Mixer, Fig. 11

Design A Low-Voltage UWB CMOS Mixer, Table

By employing bulk-injection and forward-body-bias techniques, the CMOS downconversion mixer achieves low power consumption at low supply voltage with flat conversion gain from 1.5 to 11.5 GHz. Based on a conventional Gilbert-type approach, the mixer’s new source degeneration common-source topology using four tail current sources as degeneration resistors to improve circuit linearity. Suitable for UWB applications, it exhibits maximum conversion gain of 7.2 dB with SSB noise figure of 18.4 dB and IIP3 of +6.84 dBm while consuming only 0.46 mW power from a +0.75-VDC supply.

Kehao Ma, Master’s Candidate

Chunhua Wang, Professor and Doctoral Supervisor

Xiaorong Guo, Professor and Master’s Supervisor

Wenbin Huang, Student

Hunan University, Changsha, 410082, People’s Republic of China.

Acknowledgments

This work was supported in part by the Open Fund Project of Key Laboratory in Hunan University (No. 12K012). The authors would like to thank the anonymous reviewers for their valuable suggestions, which helped improve the quality of the article.

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