19.2 A PVT-robust −39dBc 1kHz-to-100MHz integrated-phase-noise 29GHz injection-locked frequency multiplier with a 600µW frequency-tracking loop using the averages of phase deviations for mm-band 5G transceivers

Abstract

To meet requirements of high data-rates, RF transceivers for a 5G standard must have an ultra-wide bandwidth in a mm-wave band. A big challenge of a 5G transceiver is to generate ultra-low-PN (phase noise) local-oscillator (LO) signals to suppress integrated PN (IPN) over such an extremely wide bandwidth. A PLL that directly generates mm-band LO signals is not a good choice due to power-hungry frequency dividers and relatively poor PN. An mm-band LO generator, cascading a GHz-range PLL and a frequency multiplier as shown in Fig. 19.2.1, is an attractive solution. First, a GHz-range PLL can have a higher FOM than a mm-band PLL [1]. Second, the cascaded architecture is naturally able to support the bands for 2G to 4G standards. An injection-locked frequency multiplier (ILFM) is popular in a mm-band, achieving ultra-low PN even in a tight power budget. However, the vulnerability of PN to PVT variations is a critical problem. For an ILFM, the PN performance can be improved only when the free-running VCO frequency, f VCO , and the target frequency are sufficiently close within the lock range, f L , which is very narrow, especially, at high frequencies. To calibrate f VCO over PVT, many frequency-tracking loops (FTLs) have used a power-hungry circuit (such as a replica-VCO, a TDC, and a counter) operating at f VCO , but they were not suitable for a mm-band ILFM. The sub-sampling FTL [2] used the voltage levels of the VCO outputs, momentarily sampled by injection pulses. However, for the accurate sampling, the pulse width of the injection pulses must be very narrow, since the sampling occurs at the edges of the pulses. For a mm-band VCO, the pulse width must be less than 10ps, but these narrow pulses limit the injection strength and f L . In the mm-band ILFM of [3], the mixers and dividers consumed a lot of power. An envelope detector was used for another mm-band ILFM to enable the calibration operating at low frequencies [4], but it cannot detect f VCO after the VCO is injection-locked and prevent PN degradation due to real-time drifts of f VCO .