Bulk compensated CMOS squaring circuits

This paper presents the new circuit topologies of single-ended and differential CMOS squarer circuits, which rely on transistors operating in non-saturation region. It exploits the bulk compensation technique to eliminate the gamma-dependent constant in the gain definition equation, hence reducing the gain and circuit sensitivity due to process variations. Second-order analysis on the circuits demonstrates that the dominant non-ideal effects are due to mobility degradation and mismatch in devices. The theoretical prediction correlates very well with the measurement results. The experiment shows that the squarer circuit performs a good squaring function. For differential test input signal with 500 mVpp at 1 kHz, the fundamental and odd harmonics are less than 50 dB relative to the squared signal