VCO-Based ADC With Built-In Supply Noise Immunity Using Injection-Locked Ring Oscillators

Analog-to-digital converters (ADCs) based on voltage-controlled oscillators (VCOs) demonstrate superior hardware efficiency. They benefit from the technology scaling; however, they exhibit inferior performance against supply noise. The objective of this brief is, therefore, to present a VCO-based ADC architecture with built-in immunity against supply noise. The proposed technique exploits the dynamics of injection locking oscillation in multiphase ring topology. It provides a system-level cancelling of power supply noise, independent of the VCO architecture used in the time-mode ADC. The design functionality has been demonstrated using behavioral and transistor-level simulations using 65 nm technology. Under a 10% mismatch of VCO gain and a 128 MS/s data rate, the reported power supply noise rejection improvement is 25 dB, as compared with a typical VCO-based ADC.