Wide linear range voltage-controlled delay unit for time-mode signal processing

A voltage-controlled delay unit (VCDU) for low-voltage time-mode signal processing is presented in this paper. The proposed VCDU uses a signal conditioning circuit to achieve wider-range and higher linearity than state-of-the-art VCDUs. Circuit-level simulations in 0.18μm CMOS process show a linearity error of less than ± 0.2% for a 0.15 V to 1 V input range. The proposed VCDU consumes 315 μW from a 1.8 V supply at its maximum sampling frequency of 500 MHz. The proposed VCDU is validated in a first-order time-mode ΔΣ modulator application. Circuit-level simulation results of the ΔΣ modulator show a peak SNDR of 58 dB when clocked at 140 MHz with a 400 kHz bandwidth.