A 0.1–1.5 GHz 8-bit Inverter-Based Digital-to-Phase Converter Using Harmonic Rejection

This paper presents a digital-to-phase converter (DPC) with 8-bits of resolution and a wide frequency range for the input/output clocks. A harmonic rejection (HR) filter is introduced to improve linearity across a frequency range of 0.1-1.5 GHz. Instead of using time-domain averaging of phase interpolators (PI) in a conventional DPC, the frequency-domain filter directly cancels the 3rd- and 5th-order harmonics of the phase interpolated signal. The architecture is designed using an inverter-based PI circuit structure to improve power consumption and area. The inverter nonlinearity is improved using resistive averaging. The residual INL and DNL are further reduced by nonlinear weighting of the interpolation. Designed and fabricated in 65-nm CMOS technology, the DPC demonstrates a maximum INL and DNL of 1.33 and 0.52 LSB while consumes a power of 4.3 mW and occupies 0.06 mm2 area.