Flicker Phase-Noise Reduction Using Gate–Drain Phase Shift in Transformer-Based Oscillators

Abstract

This article presents a wide-band suppression technique of flicker phase noise (PN) by means of a gate-drain phase shift in a transformer-based complementary oscillator. We identify that after naturally canceling its second-harmonic voltage by the complementary operation itself, third-harmonic current entering the capacitive path is now the main cause of asymmetry in the rising and falling edges, leading to the 1/ f noise upconversion. A complete 1/ f 3 PN analysis for the transformer-based complementary oscillator is discussed. By tuning gate-drain capacitance ratio, a specific phase-shift range is introduced at the gate and drain nodes of the cross-coupled pair to mitigate the detrimental effects of ill-behaved third-harmonic voltage, thus lowering the flicker PN. To further reduce the area and improve the PN in the thermal region, we introduce a new triple-8-shaped transformer. Fabricated in 22-nm FDSOI, the prototype occupies a compact area of 0.01 mm 2 and achieves 1/ f 3 PN corner of 70 kHz, PN of −110 dBc/Hz at 1 MHz offset, figureof-merit (FoM) of −182 dB at 9 GHz, and 39% tuning range (TR). It results in the best FoM with normalized TR and area (FoM TA ) of −214 dB at 1 MHz offset.

A 30-GHz Class-F Quadrature DCO Using Phase Shifts Between Drain–Gate–Source for Low Flicker Phase Noise and I/Q Exactness

“…Furthermore, we observe a correlation between the reduction in flicker PN (i.e., PN at 10 kHz) and negative φ GD . This differs from the situation in [72] and [64] where X is set to <0.4 so as to introduce positive φ GD for the flicker PN suppression. To further quantitatively study the flicker PN in QOSCs, we use a periodic transfer function (PXF)-based flicker PN theory framework introduced in [54], [55], [73], and [74].…”

“…( As we demonstrate in [64], φ GD can be controlled by the gate-drain capacitance ratio X as follows:…”

“…Interestingly, the class-F operation by itself does not necessarily ensure a significant improvement in PN (although independently useful for the third-harmonic extraction in mm-wave frequency generation [15], [54]), since its thermal PN (i.e., PN at 10 MHz) stays almost constant from X = 1 (with V H3 /V H1 ≈ 6%) to X = 4 (with V H3 /V H1 = 30%). This is because the thermal PN caused by the 4kT γ g m noise is roughly reduced A GD times [64], [71] (rather than by the class-F itself), while…”

“…To gain better insight into the above phenomenon, we should first study the terminations of second-and thirdharmonic currents, which are the key factors causing the oscillator waveform asymmetries that lead to the non-zero net integral area of h DS • I 1/ f,rms in non-quadrature oscillators [55], [64]. As shown in Fig.…”

Multirate Timestamp Modeling for Ultralow-Jitter Frequency Synthesis: A Tutorial

“…For advanced CMOS oscillators [35]- [40] with flicker PN suppressing techniques [41]- [47], substituting L osc = 10 −140/10 rad 2 /Hz (i.e., −140 dBc/Hz) at f = 10 MHz and f osc = 10 GHz into (9) yields σ T,osc = 1 fs.…”