Wideband complementary metal–oxide–semiconductor double-bulk harmonic-rejection mixer

This paper presents the design and testing results of a complementary metal-oxide-semiconductor double-bulk harmonic-rejection (HR) mixer for wideband applications. An optimal gate-source bias voltage in the sub-threshold regime of the input transistor is found theoretically to achieve maxim HR by analysing the mixing mechanism of double-bulk mixer; and a double-bulk mixer has been designed and fabricated to verify the theoretical analysis. Test results substantiate the existence of the optimal bias point for HR of double-bulk-driven mixer when the sinusoidal local oscillator (LO) is applied. This simple but effective topology can achieve higher than 36, 44, 60 and 62 dB HR ratio for the third-, fifth-, seventh- and ninth-order of LOs, respectively, over broadband. The double-bulk mixer which input bandwidth is from 250 MHz to 3 GHz, including the buffer, consumes 5 mA current from 1 V power supply; the mixer core only consumes 1.5 mA current.