Two new VHF tunable CMOS low-voltage linear transconductors and their application to HF GM-C filter design

Two new CMOS low-voltage linear transconductors for High Frequency (HF) applications are presented. They use tunable floating voltage sources between the input and the transistor gates of each inverter that forms the transconductor proposed by Nauta (1992). Two implementations of the floating batteries are presented. The proposed transconductors operate under constant low voltage supply as low as 1.2 V and transconductance and output resistance are independently tunable. It is suitable to be used in HF continuous time filters with programmable center frequency and quality factor. To this end, simulation results of a 10.7 MHz band-pass g_m-C filter operating at a voltage supply of 1.5 V and large input swing are presented