A comparative study of the Voltage-to-Time converters (VTCs) and the Voltage-to-Frequency converters (VFCs) circuits

Nowadays ADC becomes more essential in emerging applications. ADC is starting to become hindrance to the system in the performance and the power consumption. For high-speed applications, pipelined and flash ADC has dominantly been used over the past decade. Technology scaling and the focus on digital systems with high-performance offer better time resolution by decreasing the gate delay. If the input analog voltage signal is represented in the form of time or frequency, rather than voltage, we can make use of the scaled technologies, low power consumption and die area. Time based ADC (TADC) is different from conventional ADC, because the signal is represented in the form of a stream of series time events. This architecture places the ADC at the front end to create more complex digital circuits for low power applications, and low voltage design. Simulation results show that Voltage-to-Frequency converter (VFC) circuit is better than Voltage-to-Time converter (VTC) circuit in the sensitivity, signal to noise and distortion ratio, effective number of bits, and maximum input frequency, while VTC is better than VFC with respect to the power consumption. VFC is better to be used with the applications that require high input frequency, while VTC is better to be used in applications that require low power consumption.