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This paper presents a low-voltage, low-power, low-noise, and ultra-wideband (UWB) mixer using bulk-injection and switched biasing techniques. The bulk-injection technique is implemented for a low supply voltage, thus resulting in low power consumption. This technique also allows for a flat conversion gain over a wide range of frequencies covering the full UWB band; this is a result of the integration of the RF transconductance stage and the local oscillator switching stage into a single transistor that is able to eliminate parasitic effects. Moreover, since the bulk-injection transistors of the mixer are designed to operate in the subthreshold region, current dissipation is reduced. A switched biasing technique for the tail current source, in place of static biasing, is adopted to reduce noise. The effects of modulated input signals, such as AM and FM, are simulated and measured to demonstrate the robustness of the switched biasing technique. The proposed mixer offers a measured conversion gain from 7.6 to 9.9 dB, a noise figure from 11.7 to 13.9 dB, and input third-order intercept point from - 10 to - 15.5 dBm, over 2.4 to 11.9 GHz, while consuming only 0.88 mW from a 0.8-V supply voltage. The chip size including the test pads is 0.62×0.58 mm2 using a 0.18-μm RF CMOS process.
Microwave Theory and Techniques, IEEE Transactions on (Volume:60 , Issue: 8 )
Date of Publication: Aug. 2012