Crystal oven

About: Crystal oven is a research topic. Over the lifetime, 955 publications have been published within this topic receiving 10380 citations. The topic is also known as: oven-controlled crystal oscillator & OCXO.

Design considerations for high-frequency crystal oscillators digitally trimmable to sub-ppm accuracy

Abstract: The current consumption of crystal oscillators is usually determined by the steady-state amplitude requirement, rather than the minimum transconductance for oscillation to exist, In a bipolar implementation transconductance is proportional to current, so that current consumption scales with frequency and load capacitance in the same way as transconductance. In a complementary metal-oxide-semiconductor (CMOS) implementation, current scales as the square of transconductance. It is therefore important to distinguish current from transconductance in power estimation for high frequency oscillators. Analytical expressions relating current to steady-state amplitude are used in this paper to estimate the minimum power required for a crystal oscillator at a given frequency. A 78 MHz crystal oscillator is described, which forms part of a regulated system in a pager where the oscillation frequency is controlled digitally to sub-ppm accuracy. The oscillator can be pulled from /spl plusmn/65 ppm to the required frequency with 0.2 ppm accuracy, with a maximum current consumption of 197 /spl mu/A. The circuit has been fabricated in a 1-/spl mu/m CMOS technology. The measured phase noise is -113 dBc/Hz at 300 Hz offset.

A Fully Integrated Oven Controlled Microelectromechanical Oscillator—Part II: Characterization and Measurement

Abstract: This paper, the second of two parts, reports the measurement and characterization of a fully integrated oven controlled microelectromechanical oscillator (OCMO). The OCMO takes advantage of high thermal isolation and monolithic integration of both aluminum nitride (AlN) micromechanical resonators and electronic circuitry to thermally stabilize or ovenize all the components that comprise an oscillator. Operation at microscale sizes allows implementation of high thermal resistance platform supports that enable thermal stabilization at very low-power levels when compared with the state-of-the-art oven controlled crystal oscillators. A prototype OCMO has been demonstrated with a measured temperature stability of −1.2 ppb/°C, over the commercial temperature range while using tens of milliwatts of supply power and with a volume of 2.3 mm $^{3}$ (not including the printed circuit board-based thermal control loop). In addition, due to its small thermal time constant, the thermal compensation loop can maintain stability during fast thermal transients (>10 °C/min). This new technology has resulted in a new paradigm in terms of power, size, and warm up time for high thermal stability oscillators. [2015-0036]

Temperature compensation type oscillator

Abstract: An oscillator includes a first crystal resonator, a second crystal resonator, a first amplifier circuit for oscillation, a second amplifier circuit for oscillation, a mixer circuit, a frequency selection circuit, and a first frequency conversion circuit. Assuming that resonance frequencies of the first and the second crystal resonators at a reference temperature are respectively F 1 and F 2 , and temperature coefficients expressed as a rate of change corresponding to temperatures of the resonance frequencies of the first and the second crystal resonators are respectively A 1 and A 2 , the relationship of F 2 /F 1 ≠|A 1 /A 2 | is satisfied. A signal with a temperature compensated frequency is obtained from the frequency selection circuit.

Digitally controlled temperature compensated oscillator system

Abstract: A crystal oscillator that is temperature compensated by digitally substrang a correction frequency from the running frequency of the crystal oscillator to provide the required operating frequency. The correction frequency is generated by a digital frequency synthesizer circuit which is controlled by the output of a programmable read-only memory which has been programmed to generate the required correction frequency for each temperature code over the operating temperature range. The temperature code is generated by gating a digital counter with the output of a monostable multivibrator which utilizes a thermistor to make its gate interval proportional to temperature.

Temperature compensation of a rubidium frequency standard

Abstract: A rubidium frequency standard is compensated for frequency variations over temperature by allowing the rubidium frequency standard to vary while holding the output frequency constant. A voltage controlled crystal oscillator, locked to a physics package, provides the output signal. A temperature sensor senses temperature and proves a temperature signal to a microcontroller. A frequency synthesizer receives the output signal from the voltage controlled crystal oscillator as a reference and provides an RF signal to the physics package. The microcontroller looks up a frequency error in a memory in accordance with the temperature signal, generates an offset control word for the frequency synthesizer to compensate for the temperature and adjusts the VCXO with an error signal to compensate for temperature.