Wideband injection-locked frequency divider based on a process and temperature compensated ring oscillator

The authors propose a ring-based injection-locked frequency divider (ILFD) incorporating a novel process and temperature compensation technique. The core of the ILFD consists of a process and temperature compensated ring oscillator based on modified symmetric load delay elements. Measurement results show that the natural frequency of oscillation of the ring oscillator varies only 4.4% across six different chips and for a temperature range of 0-80 degrees C. The ILFD possesses a wide locking range over process corners as well as a wide temperature range because of the proposed compensation technique and the incorporation of the delay cell architecture in the design. A calibration circuitry can be used to further enhance the locking range. Measurement results show that the proposed ILFD functions as a divide-by-4 for an input frequency range of 1.8-3.2 GHz for an input power level as low as -3 dBm. The worst-case power consumption was approximately 2 mW from a 1.8 V power supply. The proposed ILFD can be used as a low-power prescaler for multi-band applications.