The circuit architecture to generate differential CMOS quadrature (I/Q) local oscillator (LO) signals from a differential input at the same frequency is presented. The circuit features an open-loop implementation, which relies on two matched delays and linear phase interpolation. The feasibility of this approach is demonstrated by implementing an I/Q generator covering the operating frequency range from 1 to 3 GHz, manufactured in a 28-nm bulk-CMOS process. The optimum phase accuracy is better than +/- 0.4 degrees for the entire measured frequency region. A phase noise performance of -163.2 dBc/Hz at 100-MHz offset is achieved at 2 GHz with a power consumption of only 4.4 mW from a 1.1-V supply.
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