A $345\mu \mathbf{W}$ 1 GHz Process and Temperature Invariant Constant Slope-and-Swing Ramp-based 7-bit Phase Interpolator for True-Time-Delay Spatial Signal Processors

In the baseband time delay (TD) elements used for delay compensation in discrete-time beamformers, phase interpolator (PI) plays a crucial role as the resolution of the PI defines the delay resolution of the TD. In this paper, we present a process and temperature invariant high-resolution and highly linear low-power PI. The proposed PI uses current integration which generates an adaptable constant slope-and-swing ramp signal to achieve low power. By switched-capacitor bias generation, the PI linearity is enhanced with 0.2 LSB DNL and 0.3 LSB INL, respectively. The 7-bit PI is realized in 65nm CMOS technology can generate the full range delay with a resolution of 8psec with the input of 1GHz. The PI consumes a power of $\mathbf{345}\mu \mathbf{W}$ and and occupies an active area of 0.021mm2.