A Deterministic Background Calibration Technique for Voltage Controlled Oscillator Based ADC

Among different types of time-domain analog-to-digital-converters (ADCs), voltage-controlled-oscillator (VCO) based ADCs have gained prominence. Like other time-based ADCs, VCO based ADCs are amenable to CMOS technology scaling. They provide inherent anti-alias filtering to the input signal and achieve very high resolution by first order noise shaping the quantization error. Despite these advantages, traditional VCO based ADCs have found limited application due to poor linearity. Recently, several new techniques have been developed to improve the overall performance of such ADCs. This chapter briefly discusses such recent advances towards improving the performance of VCO based ADCs. A deterministic background calibration method to improve the linearity of VCO based ADCs is discussed in more detail.

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