A 0.6-V 1.6-mW transformer-based 2.5-GHz downconversion mixer with+5.4-dB gain and-2.8-dBm IIP3 in 0.13-μm CMOS

On-chip transformers are best suited to lower the supply voltage in RF integrated circuits. A design method to achieve a high current gain with an on-chip transformer operating in resonance is presented. The proposed method will be proven analytically and has been applied to a downconversion mixer. Thereby part of the overall gain of the mixer has been shifted from the RF input stage to the transformer. Thus, the power consumption has been reduced and, in spite of the low supply voltage, moderate linearity has been achieved. Although the transformer has a bandpass behavior, a 3-dB bandwidth of 900 MHz at a center frequency of 2.5 GHz has been achieved. The downconversion mixer has been realized in 0.13-mum CMOS. It consumes 1.6 mW from a 0.6-V supply. A gain of +5.4 dB, a third-order intercept point of -2.8 dBm, an input 1-dB compression point of -9.2 dBm, and a single-sideband noise figure of 14.8 dB have been achieved.