A 2.3-mW 0.01-mm $^{\text{2}}$ 1.25-GHz Quadrature Signal Corrector With 1.1-ps Error for Mobile DRAM Interface in 65-nm CMOS

Abstract

In this brief, we propose a quadrature signal corrector for a low-power DDR4 mobile DRAM interface. In order to eliminate the phase imbalance among quadrature signals, the proposed architecture employs digitally controlled delay lines in a shared digital feedback loop with a time-multiplexed loop filter so as to minimize the effect of circuit mismatch that hampers the phase accuracy. A self-calibrated offset delay is also proposed, which allows the use of a simple 1-bit TDC instead of a power-hungry wide-dynamic range TDC. Implemented in 65-nm CMOS, the prototype chip achieves less than 1.1-ps phase error for a 1.25-GHz quadrature signal and occupies an active area of only 0.01 mm2 while consuming 2.27 mW from a 1.0-V supply.