Sub 1-V highly-linear low-power class-AB bulk-driven tunable CMOS transconductor

This paper describes the design and realization of a sub 1-V low power class-AB bulk-driven tunable linear transconductor using a 0.18-mu m CMOS technology. The proposed transconductor employs a class-AB bulk-driven differential input voltage follower and a passive resistor to achieve highly linear voltage-to-current conversion. Transconductance tuning is achieved by tuning the differential output current of the core transconductor with gain-adjustable current mirrors. With 10.4-mu A current consumption from a 0.8-V single power supply voltage, simulation results show that the proposed transconductor achieves the total harmonic distortion (THD) of <-40 dB for a peak differential input voltage range of 800 mV at frequencies up to 10 kHz. The simulated input-referred noise voltage integrated over 10-kHz bandwidth is 100 mu V, resulting to an input signal dynamic range of 75 dB for THD <-40 dB. A biquadratic G(m)-C filter is designed to demonstrated the performance of the proposed transconductor. At the nominal 10-kHz cut-off frequency, the filter dissipates 34.4 mu W from a 0.8-V supply voltage and it achieves an input signal dynamic range of 67.4 dB for the third-order intermodulation distortion of <-40 dB.