A time-to-digital converter based AFC for wideband frequency synthesizer

Abstract The automatic frequency calibration (AFC) technique is routinely used in wideband frequency synthesizers that contain multiple voltage-controlled oscillator (VCO) tuning curves. In this paper, a counter-based AFC that uses a time-to-digital converter (TDC) in the counting process is developed. The TDC is able to capture the fractional VCO cycle information within the counting window. This significantly improves the frequency detection accuracy over the existing counter-based AFC techniques. In addition, a quantitative model is developed to determine the minimally required error-free AFC calibration time for a given VCO tuning curve characteristic. An AFC circuit using the proposed TDC-based counter is designed in a 0.13-μm CMOS technology. Simulation results show that the proposed AFC significantly improves the frequency detection accuracy and consequently for a given frequency detection resolution reduces the AFC calibration time. The simulated error-free AFC time is <2.5 μs with a frequency resolution of 0.04 %.

[1]  Enrico Temporiti,et al.  A 3 GHz Fractional All-Digital PLL With a 1.8 MHz Bandwidth Implementing Spur Reduction Techniques , 2009, IEEE Journal of Solid-State Circuits.

[2]  Byeong-Ha Park,et al.  A /spl Sigma/-/spl Delta/ fractional-N frequency synthesizer using a wide-band integrated VCO and a fast AFC technique for GSM/GPRS/WCDMA applications , 2004 .

[3]  Wei Li,et al.  A time-to-digital converter based AFC for wideband frequency synthesizer , 2012, 2012 IEEE International Symposium on Circuits and Systems.

[4]  Salvatore Levantino,et al.  A glitch-corrector circuit for low-spur ADPLLs , 2009, 2009 16th IEEE International Conference on Electronics, Circuits and Systems - (ICECS 2009).

[5]  William J. Kaiser,et al.  A 900-MHz 2.5-mA CMOS frequency synthesizer with an automatic SC tuning loop , 2001 .

[6]  Poras T. Balsara,et al.  1.3 V 20 ps time-to-digital converter for frequency synthesis in 90-nm CMOS , 2006, IEEE Transactions on Circuits and Systems II: Express Briefs.

[7]  Jaewook Shin,et al.  A Fast and High-Precision VCO Frequency Calibration Technique for Wideband $\Delta \Sigma $ Fractional-N Frequency Synthesizers , 2010, IEEE Transactions on Circuits and Systems I: Regular Papers.

[8]  Tsung-Hsien Lin,et al.  An Agile VCO Frequency Calibration Technique for a 10-GHz CMOS PLL , 2007, IEEE Journal of Solid-State Circuits.

[9]  Wei Li,et al.  A Frequency Synthesizer With Optimally Coupled QVCO and Harmonic-Rejection SSBmixer for Multi-Standard Wireless Receiver , 2011, IEEE Journal of Solid-State Circuits.