A DC-10Â GHz amplifier with digital offset correction

This work presents a SiGe:C wideband amplifier with a binary CMOS counter for digital offset adjustment. The application of the “radix<2” approach to accurate offset correction in a digital calibration loop results in smaller area and less power than common static high-resolution offset correction circuits. The counter bits are weighted with a radix of 1.6, leading to 25% error tolerance, and thus simple circuits and small devices. A BiCMOS test chip in a 0.25-μm-CMOS 200-GHz-SiGe:C technology exhibits a correction accuracy well below the measurement noise floor of 50 μV at only 1 mW additional power consumption. The amplifier operates from DC to 10 GHz on a 3 V supply voltage. Since the adjustment compensates device mismatch, minimum-size transistors can be used. This in turn enhances the RF performance.