Crystal

This 40KHz crystal controlled oscillator circuit drives an infrared LED with powerful 40ma pulses. The circuit can be used to test optical communications circuits, designed to receive 40KHz modulated light signals...

I have used this circuit many times when I needed a low frequency reference, which did not draw much power. With the components show, the current from a 3v battery is less than 1.2 microamps...

The circuit gates the output of a continuously operating 32KHz crystal oscillator to the input of a C-MOS buffer when clock pulses are needed. The technique gets around the problem of a slow starting crystal oscillator by keeping the oscillator going and switching on a transistor power stage only as needed. The method keeps the standby power consumption to a very low 1uA when used with a 3v supply...

The AD9850 complete direct digital synthesizer (DDS) is a popular device used to implement a low cost, high speed, digital synthesis system. Clocking the AD9850 at its maximum rate of 125 MHz may present some technical challenges especially in applications where the phase noise of the sine output is a major concern...

The RF engineer sometimes has to look for an instrument that will check a low frequency quartz crystal unit reliably and rapidly. This is a difficult piece of equipment to find and the engineer often has to consult an electronic circuits handbook for the schematic of a circuit that will perform the task...

This is an image Schematic. No Description available...

This is an image Schematic. No Description available...

The world is full of xtal oscillators twiddled by digital designers lacking in the analog design knowledge necessary. Just look at all the PC real time clocks that lags or leads by several minutes per day. And they eat backup batteries too! IC`s with pins that say "Xtal here" can`t be trusted either!..

This is an image Schematic. No Description available...

With the advent of high speed HCMOS circuits, it is possible to build systems with clock rates of greater than 30 MHz. The familiar gate oscillator circuits used at low frequencies work well at higher frequencies and either LC or crystal resonators maybe used depending on the stability required. Above 20 MHz, it becomes expensive to fabricate fundamental mode crystals, so overtone modes are used...

Starting up oscillator circuits and getting them to maintain oscillation in a Spice simulation is difficult. Some high-frequency crystal circuits require days for the oscillation to reach steady state. Thus, most designers separate the crystal`s circuit simulation from the rest of the system design. However, a technique that gives a "kick" to an RLC equivalent circuit solves this problem. This method makes sure the simulation starts fast and quickly reaches the steady state...

The Pierce oscillator shown above is essentially a common emitter amplifier with a tuned circuit for a collector load and a quartz crystal as a feedback element. In order to determine whether the Barkhausen criteria is satisfied, loop gain must be determined at the frequency of oscillation. This is accomplished by drawing the AC equivalent circuit of the Pierce Oscillator as shown below...

The crystal used in the topology of Figure 1 can be either a fundamental AT-CUT or BT-CUT. A BT-CUT crystal has poor frequency stability over temperature compared to an AT-CUT. This topology uses a parallel crystal and not a series crystal...

This article explains the specifications and characteristics of crystals and crystal oscillators, and aids in specifying crystals and working with crystal vendors. The article covers the significant performance characteristics of crystals, which include resonance frequency, resonance mode, load capacitance, series resistance, holder capacitance, motional inductance and capacitance, temperature calibration, and drive level...

The most important characteristic of CMOS-COPS is its low power consumption. This low power feature does not exist in TTL and NMOS systems which require the selection of low power IC`s and external components to reduce power consumption...