An Injection Frequency-Locked Loop—Autonomous Injection Frequency Tracking Loop With Phase Noise Self-Calibration for Power-Efficient mm-Wave Signal Sources

Abstract

This paper presents a fast and autonomous injection frequency tracking and locking technique. In the present injection-locking system, a quadrature injection-locked oscillator (QILO) is third harmonically locked to a quadrature voltage-controlled oscillator (QVCO). In the frequency tracking loop, the frequency difference between QVCO and QILO is extracted using the QILO’s amplitude modulated (AM) envelope waveform. The AM frequency of the envelope signal bears frequency difference between the two oscillators. The envelope signal is further converted to pulse signal which subsequently drives digital feedback control circuitry to update the QILO’s output frequency so that it can track the third harmonic of the injection QVCO. The frequency calibration process is purely autonomous, self-initiating whenever the AM modulated envelope waveform is generated. The feedback signal is primarily processed in the digital domain, resulting in a compact, fast, and power-efficient injection frequency-locked loop (IFLL). By incorporating a phase noise (PN) calibration routine after completing the frequency calibration, the presented IFLL resolves the intractable issue of PN degradation at the edge of the slave oscillator’s injection locking range. This results in a large injection frequency tracking range of 26.5–29.7 GHz which is only limited by the QILO’s LC tank tuning range. The IFLL realized in 0.13- $\mu \text{m}$ CMOS consumes 2.4 mW with a negligible area penalty. Overall chip size including QVCO, QILO, and IFLL is $1 \times 1$ mm2.