# Tag Info

## Hot answers tagged oscillator

3

If it is really that hard to gauge correctly, why don't manufacturers provide better guidance? Oscillator designers have a tough job accommodating resonators over a very wide frequency range, and whose power-handling might range from fractions-of-microwatts to milliwatts. The oscillator driver runs in its linear region - a no-no for digital CMOS devices. ...

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but my circuit is extremely not effective You certainly have problems with your transmitter: - You have the MOSFET gates connected to ground and this means it can never work.

2

A fractional frequency divider is rarely used by itself to provide a divided-down output. Although the divider you describe would on average produce an f0/2.5 signal, such a signal is rarely useful due to the large amount of jitter it has on it, as edges on the output signal obviously have to align with input signal edges. Instead, a fractional divider is ...

2

Most MCU datasheets and application notes do list some limits for the crystal, the loading capacitors, or at least they list some oscillator parameters to work with. For instance the STM32 application note you mentioned shows how to calculate if the crystal is compatible or not. If it is not compatible, try another crystal, perhaps with smaller frequency, ...

2

Eric Vittoz was the analog IC designer who brought nanoWatt crystal oscillator methods to the Swiss watch industry. As part of that research effort, he published a paper on "too high a gain in the amplifier will prevent crystal/circuit oscillation", where the math shows root-locus plots at high transconductances crossing the ZERO phaseshift axis, quelling ...

1

Ouch! The opamp is used in non-linear mode. Linear opamp circuit calculation practices nor transfer functions are not applicable for it. You should divide this to a Schmitt-trigger and a charging and discharging RC circuit. Then you can find how long it takes for the RC circuit to charge and discharge between the tresholds of the Schmitt-trigger. ADD you ...

1

The damping ratio $\zeta$ (zeta) of a $RLC$ filter can be evaluated using the logarithmic decrement $\delta$ (delta): $\delta=ln(\alpha)=\frac{2\pi}{\sqrt{4Q^2-1}}$ from which you extract $Q$ or $\zeta$ as detailed in the book I published on loop control: $\zeta = \frac{1}{\sqrt{(\frac{2\pi}{\delta})^2+1}}$. Let's see a practical application ...

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The output of the phase comparator is the same : the output of the "loop filter" is not. To achieve zero phase error, you need infinite gain at zero frequency; i.e. a component of the loop filter is an integrator. An easier way to think of the loop filter, in this case, is as a PI controller, with the P (Proportional) term providing fast tracking of phase ...

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Figure 3-4 is showing an oscillator instead of a crystal. The XO pin on the PHY is meant to provide an excitation source for a crystal located close to the IC. However, an oscillator contains this excitation source along with other circuitry to stabilize it and provide an output clock. Connect this output to both the PHY's XI pin and the MAC's REF_CLK pin. ...

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