8128B Datasheet, PDF (1/5 Pages) ATMEL Corporation – Typical Crystal/Resonator Oscillator

AVR 8-bit Microcontrollers
AVR186: Best Practices for the PCB Layout of
Oscillators
APPLICATION NOTE
Introduction
The Pierce oscillator (most common case) implemented in microcontrollers
is built up around a class A amplifier and a narrow band filter such as a
crystal or a ceramic resonator as shown in the below figure.
Figure -1. Typical Crystal/Resonator Oscillator
CXta lin
Vdd
Xta lin
Amplifie r
CXta lout
Crys ta l
Re s ona tor
Xta lout
Vs s
This device has a high input impedance characteristic outside of the
resonance frequency range and has a low input impedance characteristic at
the oscillation frequency.
The high impedance characteristic degrades its immunity when an electrical
field is applied in its vicinity.
Furthermore, in the latest technology and also in order to reduce the
consumption, the oscillation level is restricted to within the range of 1V, again
increasing the susceptibility.
Atmel-8128B-Best-Practices-for-the-PCB-Layout-of-Oscillators_AVR186_Application Note-09/2016