A novel 12-bit, 3 μs, integrating-type CMOS analog-to-digital converter

A 12-bit resolution, 3 μs conversion time, integrating-type CMOS analog-to-digital converter is described. The converter is specially intended for applications that require low values of integral and differential non-linearity. The circuit features a linear ramp generation whose slope depends on the polarity of the input signal and a time converter using interpolation techniques within one cycle of the clock. The architecture allows a wide signal input range and an equivalent clock speed in excess of 1 GHz, leading to a significant reduction in the conversion time, while improving on DNL and INL. An integrated circuit has been fabricated for demonstration purposes, using a widely available 1.2 μm CMOS technology