[1]Radio in 130-nm CMOS,” IEEE J. Solid-State Circuits, vol. 39, no. 12, pp. 2278–2291, Dec. 2004.
[2]J. Kim, T. Jang, Y. Yoon and S. H. Cho, “Analysis and design of voltage-controlled oscillator based analog-to-Digital converter,” IEEE Trans. Circuits Syst. I, Reg. Papers, vol. 57, pp. 18–30, Jan. 2010.
[3]J. Kim and S. H. Cho, “A time-based analog-to-digital converter using a multi-phase voltage-controlled oscillator,” in Proc. IEEE Int. Symp.Circuits Syst. , pp. 3934–3937 May 2006.
[4]M. Z. Straayer and M. H. Perrott, “A 10-bit 20 MHz 950 MHz CT ∑∆ ADC with a 5-bit noise-shaping VCO-based quantizer and DEM circuit in 0.13 u CMOS,” in Proc. IEEE Int. Conf. VLSI Des. , pp.246–247 Jan. 2007.
[5]M. Z. Straayer and M. H. Perrott, “A 12-bit, 10 MHz bandwidth, continuous-time ∑∆ ADC with a 5-bit, 950 MS/s VCO-based quantizer,” IEEE J. Solid-State Circuits, vol. 43, no. 4, pp. 805–814, Apr. 2008.
[6]L. Hernandez, S. Paton and E. Prefasi, “VCO-based sigma delta modulator with PWM precoding,” Electron. Lett., vol. 47, no. 10, pp. 588–589, 2011.
[7]S. Rao, “A 71 dB SFDR open loop VCO-based ADC using 2-level PWM modulation,” in Proc. IEEE Symp. VLSI Circuits Dig. Tech. Papers, pp. 270–271, Jun. 2011.
[8]L. Hernandez, “VCO based multi-stage noise shaping ADC,” Electron. Lett., vol. 48, no. 4, pp. 206–208, Feb. 2012.
[9] Y. Wonsik and K. Jaewook, “A Time-Domain High-Order MASH ∆∑ ADC Using Voltage-Controlled Gated-Ring Oscillator,” IEEE Trans. Circuits Syst. I Reg. Papers, vol. 60, pp. 856–866, Apr. 2013.
[10]I. Kazi, Low Power Current Mode sigma-delta ADC using a Ring Oscillator based Quantizer, Master thesis, Royal Institute of Tech., Sweden, 2012.
[11]M. Z. Straayer and M. H. Parrott, “A multi-path gated ring oscillator TDC with first-order noise shaping,” IEEE J. Solid-State Circuits, vol. 44, no. 4, pp. 1089–1098, Apr. 2009.
[12]D. Johns and K. Martin, Analog Integrated Circuit Design. New York: Wiley, 1997.
[13]Z. Song and D. Sarwate, “The frequency spectrum of pulse width modulated signals,” Signal Processing, no.10, pp. 2227-2258, Oct. 2003.
[14]M. Z. Straayer, Noise Shaping Techniques for Analog and Time to Digital Converters Using Voltage Controlled Oscillators, Ph.D thesis, MIT, Cambridge, MA, 2008.
[15]R. Navid, T. H. Lee and R. W. Dutton, “Minimum achievable phase noise of RC oscillators,” IEEE J. Solid-State Circuits, vol. 40, no. 3,pp. 630–637, Mar. 2005.
)