Wideband ring mixer for band #1 of MB-OFDM systems
in 180 nm CMOS technology

Abhay Chaturvedi – Mithilesh Kumar –
Ram Swaroop Meena – Gaurav Kumar Sharma

   A wideband down conversion ring mixer is proposed for multi band orthogonal frequency division multiplexing (MB-OFDM) system in 180 nm CMOS technology. The mixer is essentially used in a heterodyne wireless receiver to enhance the selectivity of the system. Being a nonlinear system, the mixer dominates the overall performance of the system. The design of down conversion mixer is the most challenging part of a receive chain. Wideband impedance matching always remains a challenge in any radio frequency integrated circuit design. This paper presents the design of a ring mixer with high linearity, wideband impedance matching using differential resistive impedance matching and without using any DC bias. The proposed mixer is tuned for a frequency of 3.432 GHz of band 1 of the MB-OFDM system. Mixer core is based on the FET ring mixer topology. The mixer is implemented in 180 nm CMOS technology. The mixer achieves the minimum conversion loss of 10.49 dB, 1 dB compression point (P1) of 12.40 dBm, third order input intercept point (IIP3) of 12.01 dBm, a minimum SSB noise figure of 8.99 dB, and S₁₁ of less than –10 dB over the frequency range of 0 to 13.61 GHz. The layout of the mixer records an active area of 183.75 μm ².

Keywords: MB-OFDM, mixer, ring topology, wideband, CMOS

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