Frequency drift

About: Frequency drift is a research topic. Over the lifetime, 5054 publications have been published within this topic receiving 56191 citations. The topic is also known as: chirp rate.

A 51.3-MHz 21.8-ppm/°C CMOS Relaxation Oscillator With Temperature Compensation

Abstract: A 51.3-MHz 18- $\mu\text{W}$ 21.8-ppm/°C relaxation oscillator is presented in 90-nm CMOS. The proposed oscillator employs an integrated error feedback and composite resistors to minimize its sensitivity to temperature variations. For a temperature range from −20 °C to 100 °C, the fabricated circuit demonstrates a frequency variation less than ±0.13%, leading to an average frequency drift of 21.8 ppm/°C. As the supply voltage changes from 0.8 to 1.2 V, the frequency variation is ±0.53%. The measured rms jitter and phase noise at 1-MHz offset are 89.27 ps and −83.29 dBc/Hz, respectively.

Trimming of a two point phase modulator

Abstract: Method and system are disclosed for automated calibration of the VCO gain in phase modulators. The method and system of the invention comprises synthesizing, in a phase modulator, a signal having a given output frequency using a controlled oscillator having a frequency control input, a modulation input, and a feedback loop. A frequency control signal is applied to the frequency control input, and gain variation of the controlled oscillator is compensated for outside of the feedback loop via the modulation input. The method and system of the invention may be employed in any telecommunication system that uses phase and amplitude modulation, including EDGE and WCDMA systems.

Electronic Temperature Compensation of Lateral Bulk Acoustic Resonator Reference Oscillators Using Enhanced Series Tuning Technique

Abstract: This paper reports on the demonstration of series tuning for lateral micromechanical oscillators and its application for electronic temperature compensation of piezoelectric lateral bulk acoustic resonator (LBAR) micromechanical oscillators. Two aluminum nitride-on-silicon (AlN-on-Si) piezoelectric LBARs, one operating at 427 MHz (Rm ≈180 Ω, Qunloaded ≈ 1400) and the other operating at 541 MHz (Rm ≈ 55 Ω, Qunloaded ≈ 3000) are interfaced with a 13 mW three-stage tunable TIA implemented in 0.18 μm 1P6M CMOS process to sustain the oscillation. Recognizing the impact on the frequency tuning range due to the body capacitances appearing in parallel with the ports of the resonator, the TIA uses parasitic cancellation techniques to neutralize this effect and boost the tuning range of 427 MHz and 541 MHz oscillators, by as much as 12× to 810 ppm and 1,530 ppm, respectively, with negligible impact on the phase noise performance. The shunt parasitic capacitor is either resonated out with an active inductor or is cancelled out by using a single-terminal negative capacitor of equal value. However, the oscillator that uses negative capacitance parasitic cancellation yields larger tuning. This extended tuning range is used for temperature compensation. A 2 mW bandgap-based temperature compensation circuit which uses second-order parabolic approximation is fabricated on the same chip. Using this temperature compensation circuit has lowered the overall frequency drift of a 427 MHz tunable oscillator using negative capacitance cancellation from ±390 ppm to ±35 ppm in the -10°C to 70°C temperature range. The phase noise of this oscillator reaches -82 dBc/Hz at 1 kHz offset. The total phase noise variation for offset frequencies below 10 kHz is under 5 dB within the specified tuning range, and the best phase noise floor is under -147 dBc/Hz . Due to the higher Q and lower insertion loss of the resonating tank, the 541 MHz oscillator achieves -86 dBc/Hz at 1 kHz offset, and lower phase noise floor of -158 dBc/Hz.

Reduction of frequency noise and frequency shift by phase shifting elements in frequency modulation atomic force microscopy.

Abstract: We recently reported the analysis of the frequency noise in the frequency modulation atomic force microscopy (FM-AFM) both in high-Q and low-Q environments [Rev. Sci. Instrum. 80, 043708 (2009)]. We showed in the paper that the oscillator noise, the frequency fluctuation of the oscillator, becomes prominent in the modulation frequency lower than f(0)∕2Q, where f(0) and Q are the resonance frequency and Q-factor. The magnitude of the oscillator noise is determined by the slope of the phase versus frequency curve of the cantilever at f(0). However, in actual FM-AFM in liquids, the phase versus frequency curve may not be always ideal because of the existence of various phase shifting elements (PSEs). For example, the spurious resonance peaks caused by the acoustic excitation and a band-pass filter in the self-oscillation loop increase the slope of the phase versus frequency curve. Due to those PSEs, the effective Q-factor is often increased from the intrinsic Q-factor of the cantilever. In this article, the frequency noise in the FM-AFM system with the PSEs in the self-oscillation loop is analyzed to show that the oscillator noise is reduced by the increase of the effective Q-factor. It is also shown that the oscillation frequency deviates from the resonance frequency due to the increase of the effective Q-factor, thereby causing the reduction in the frequency shift signal with the same factor. Therefore the increase of the effective Q-factor does not affect the signal-to-noise ratio in the frequency shift measurement, but it does affect the quantitativeness of the measured force in the FM-AFM. Furthermore, the reduction of the frequency noise and frequency shift by the increase of the effective Q-factor were confirmed by the experiments.

A tunable flipflop-based frequency divider up to 113 GHz and a fully differential 77GHz push-push VCO in SiGe BiCMOS technology

Abstract: We present a tunable flipflop-based frequency divider and a fully differential push-push VCO designed in a 200GHz f T SiGe BiCMOS technology. A new technique for tuning the sensitivity of the divider in the frequency range of interest is presented. The chip works from 60GHz up to 113GHz. The VCO is based on a new topology which allows generating differential push-push outputs. The VCO shows a tuning range larger than 7GHz. The phase noise is 75dBc/Hz at 100kHz offset. The chip shows a frequency drift of 12.3MHz/C. The fundamental signal suppression is larger than 50dB. The output power is 2×5dBm. At a 3.3V supply, the circuits consume 35mA and 65mA, respectively.