A novel harmonic selection technique based on the injection of a periodically repeated oscillations train into an oscillator

Abstract

A new concept based on the injection of a period icall y repeated oscillations train into an oscillator is presented.It is based on a phenomenon named pseudo-locking, leading to a novel harmonic selection technique. Theoretical description of the concept is presented, in particular an anal y tical condition is carried out, paving the wa y of design rules. For a proof of concept, an oscillator fabricated on a 40 nm CMOS technolog y was measured. The concept was validated b y measured phase noise equivalent to classical fundamental injection locking phase noise performance.

Analysis of high-order sub-harmonically injection-locked oscillators

“…To facilitate the locking, the input dc block has been suppressed. Although the oscillation frequency of this prototype (2.7 GHz) is lower than the one in [1]- [3], the frequency ratio is the same N = 30, so the analysis complexity must be similar. The circuit has been analysed with circuit-level envelope transient, following the criteria in (6), and using an auxiliary generator (AG) at fo, connected to the circuit at the initial time only [6], to initialize the oscillation.…”

“…The recent works [1]- [3] present a frequency-synthesis technique based on the subharmonic injection locking of an oscillator at a frequency fo by an independent source at a much lower frequency. The high ratio N between the two frequencies (in the order of N = 30) is enabled by the periodic switching of the higher frequency oscillator by a low frequency input, which gives rise to a high number of spectral lines at the oscillator output.…”

“…The high ratio N between the two frequencies (in the order of N = 30) is enabled by the periodic switching of the higher frequency oscillator by a low frequency input, which gives rise to a high number of spectral lines at the oscillator output. This output signal is introduced into a second oscillator, which gets locked to one or another spectral line, depending on its tuning voltage [1]- [3]. Thus, the combination of the two oscillators enables a programmable frequency selection, with frequency spacing fo/N.…”

“…However, the realistic simulation of this complex system is extremely demanding and, to our knowledge, has not been carried out in any previous work. In [1]- [3] the injection-locked oscillator (ILO) is analyzed in time domain, using simplified models of the Van der Pol type. Then, the synchronization bandwidths are detected through a comparison of the oscillation amplitude and phase values at the beginning and end of each period of the switching signal.…”

Analysis of high-order sub-harmonically injection-locked oscillators

“…The recent works [1][2][3][4][5][6][7] have demonstrated a novel frequency-synthesis methodology, based on the high-order sub-harmonic injection-locking of a high-frequency oscillator, at a frequency f o , by an independent source at a much lower frequency f in . In [1][2][3], the high ratio N between the two frequencies (in the order of N = 30) is achieved by shaping the input sinusoidal signal into a square signal that periodically switches on and off a high-frequency oscillator. This is used to injection lock a second oscillator that selects the harmonic closest to its own free-running frequency.…”