Linearity Enhancement using Bulk-Degeneration for Source Degenerated OTAs

A modified bulk degeneration technique for source-degenerated OTAs is proposed in this paper. The approach employs drain voltage division and cross-coupling the resultant voltage to the bulk terminal of differential pair which reduces third harmonic distortion (HD
₃
). Simulations are carried on 0.18 μm process with 1.8 V power supply which shows that HD
₃
is decreased by 14 dB (for frequencies of 100 KHz) as compared to previously reported bulk degenerated transconductors. An added advantage is the variation of DC transconductance using the resistance ratio of the voltage divider circuit which offers the tunability in the transconductance.