Fundamental-frequency-crystal-oscillator


Posted on Jun 29, 2012    8951

For frequencies below 20 MHz, a fundamental-frequency crystal can be used and the resonant tank is no longer required. Also, at this lower frequency range the typical MECL 10,000 propagation delay of 2 ns becomes small compared to the period of oscillation, and it becomes necessary to use a noninverting output. Thus, the MC10116 oscillator section functions simply as an amplifier. The 1.0 Kohm resistor biases the line receiver near `BB and the 0.1-uF capacitor is a filter capacitor for the `Vbb supply.


Fundamental-frequency-crystal-oscillator
Click here to download the full size of the above Circuit.

The capacitor, in series with the crystal, provides for minor frequency adjustments. The second section of the MC10116 is connected as a Schmitt-trigger circuit; this ensures good MECL edges from a rather slow, less than 20MHz input signal. The third stage of the MC10116 is used as a buffer and to give complementary outputs from the crystal oscillator circuit. The circuit has a maximum operating frequency of approximately 20 MHz and a minimum of approximately 1 MHz; it is intended for use with a crystal which operates in the fundamental mode of oscillation.




Leave Comment

characters left:

New Circuits

.


Top