- ELECTRONICS LETTERS Journal
- March 2014
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- Oversaw led converters based on voltage controlled ring oscillators are an attractive solution because of their digital implementation and simplicity. However, the voltage-to-frequency conversion of ring oscillators displays a poor linearity. Replacing the ring oscillator by a pulse frequency modulator (PFM) that provides improved linearity at the expense of feedback and analogue amplification is proposed. Compared to the equivalent continuous time sigma delta modulators, the PFM may be more tolerant to circuit impairments. In addition, the output data of the proposed architecture is a multibit sequence through the use of a time-to-digital converter TDC instead of a Flash quantiser or a multibit digital-to-analogue converter. A high dynamic range can be achieved without severe constraints on analogue mismatch or clock jitter.
- pulse frequency modulation; time-digital conversion; modulators; oversampled adc; pulse frequency modulator; tdc; voltage controlled ring oscillators; oversampled converters; digital implementation; voltage-frequency conversion; pfm; analogue amplification; equivalent continuous-time sigma-delta modulators; multibit sequence; time-to-digital converter; flash quantizer; multibit digital-to-analogue converter; multibit dac; dynamic range; analogue mismatch; clock jitter