Now showing 1 - 3 of 3
  • Publication
    A 1/f noise up-conversion reduction technique for voltage-biased RF CMOS oscillators
    In this paper, we propose a method to reduce a flicker (1/f) noise upconversion in voltage-biased RF oscillators. Excited by a harmonically rich tank current, a typical oscillation voltage waveform is observed to have asymmetric rise and fall times due to even-order current harmonics flowing into the capacitive part, as it presents the lowest impedance path. The asymmetric oscillation waveform results in an effective impulse sensitivity function of a nonzero dc value, which facilitates the 1/f noise upconversion into the oscillator's 1/f3 phase noise. We demonstrate that if the ω0 tank exhibits an auxiliary resonance at 2ω0, thereby forcing this current harmonic to flow into the equivalent resistance of the 2ω0 resonance, then the oscillation waveform would be symmetric and the flicker noise upconversion would be largely suppressed. The auxiliary resonance is realized at no extra silicon area in both inductor-and transformer-based tanks by exploiting different behaviors of inductors and transformers in differential-and common-mode excitations. These tanks are ultimately employed in designing modified class-D and class-F oscillators in 40 nm CMOS technology. They exhibit an average flicker noise corner of less than 100 kHz.
    Scopus© Citations 124  858
  • Publication
    A 0.5V 0.5mW switching current source oscillator
    This paper proposes a new RF oscillator topology that is suitable for ultra-low voltage and power applications. By employing alternating current source transistors, the structure combines the benefits of low supply voltage operation of conventional NMOS cross-coupled oscillators together with high current efficiency of the complementary push-pull oscillators. In addition, the 1/f noise upconversion is also reduced. The 40nm CMOS prototype exhibits an average FoM of 189.5 dBc/Hz over 4–5 GHz tuning range, dissipating 0.5mW from 0.5V power supply, while abiding by the technology manufacturing rules.
    Scopus© Citations 13  596
  • Publication
    A 1/f noise upconversion reduction technique applied to class-D and class-F oscillators
    The 1/f (flicker) noise upconversion degrades the close-in spectrum of CMOS RF oscillators. The resulting 1/f3 phase noise (PN) can be an issue in PLLs with a loop bandwidth of <;1MHz, which practically implies all cellular phones. A previously published noise-filtering technique [1] and adding resistors in series with gm-device drains [2] have shown significant reduction of the 1/f3 oscillator PN corner. However, the former needs an additional tunable inductor and the latter degrades PN in the 20dB/dec region.
      1185Scopus© Citations 40