A Low-Noise WLAN Mixer Using Switched Biasing Technique

A low-noise CMOS down-conversion mixer for WLAN applications is presented in this letter. The proposed mixer is based on the conventional Gilbert-type topology with switched biasing technique for a current source instead of static biasing, which lowers noise over a wide range of frequencies. Moreover, a dc level shifter is used for the symmetric switching operation in tail current transistors. A current bleeding technique is adopted to reduce the noise caused by the LO switching operation. The proposed mixer was fabricated using a 0.18 mum 1P6M CMOS process. Measurement results include a conversion gain of 7.5 dB, an IIP3 of -5 dBm, and noise figures of 10.9 dB at 1 MHz and 7.6 dB at 100 MHz. The mixer core consumes a current of 4.5 mA from a supply voltage of 1.8 V. The chip size, including pads for measurements, is 0.88 times 0.88 mm2.

[1]  Kiat Seng Yeo,et al.  RF CMOS low-phase-noise LC oscillator through memory reduction tail transistor , 2004, IEEE Trans. Circuits Syst. II Express Briefs.

[2]  Bumman Kim,et al.  A New RF CMOS Gilbert Mixer With Improved Noise Figure and Linearity , 2008, IEEE Transactions on Microwave Theory and Techniques.

[3]  T. Manku,et al.  A charge-injection method for Gilbert cell biasing , 1998, Conference Proceedings. IEEE Canadian Conference on Electrical and Computer Engineering (Cat. No.98TH8341).

[4]  R.C. Jaeger,et al.  A Direct-Conversion Mixer with a DC-offset Cancellation for WLAN , 2007, 2007 IEEE Bipolar/BiCMOS Circuits and Technology Meeting.

[5]  E. Klumperink,et al.  Reducing MOSFET 1/f noise and power consumption by switched biasing , 1999, IEEE Journal of Solid-State Circuits.

[6]  J. Laskar,et al.  Design and Analysis of Low Flicker-Noise CMOS Mixers for Direct-Conversion Receivers , 2006, IEEE Transactions on Microwave Theory and Techniques.

[7]  H.-R. Chuang,et al.  A 5.7-GHz low-power and high-gain 0.18-/spl mu/m CMOS double-balanced mixer for WLAN , 2005, 2005 European Microwave Conference.

[8]  L. Noor,et al.  Direct conversion receiver for radio communication systems , 2005, IEEE Potentials.

[9]  A.A. Abidi,et al.  Noise in RF-CMOS mixers: a simple physical model , 2000, IEEE Journal of Solid-State Circuits.

[10]  H. Sato,et al.  A Low Flicker-Noise Direct Conversion Mixer in 0.13 um CMOS with Dual-Mode DC offset Cancellation Circuits , 2007, 2007 Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems.