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Clock generator
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<p>A clock generator is an <a href="/facts/Electronic_oscillator/6NaXsSzJ">electronic oscillator</a> that produces a <a href="/facts/Clock_signal/9UfTzGHx">clock signal</a> for use in synchronizing a circuit's operation. The output <a href="/facts/Clock_signal/9UfTzGHx">clock signal</a> can range from a simple symmetrical <a href="/facts/Square_wave_(waveform)/h1cWR1KM">square wave</a> to more complex arrangements. The basic parts that all clock generators share are a resonant circuit and an amplifier. </p><p>The resonant circuit is usually a <a href="/facts/Quartz/4n86tE2G">quartz</a> <a href="/facts/Piezoelectricity/65k6BDqx">piezo-electric</a> <a href="/facts/Crystal_oscillator/QhhohzPu">oscillator</a>, although simpler <a href="/facts/Tank_circuit/tzEfI7Hf">tank circuits</a> and even <a href="/facts/RC_circuit/6WCu8sAc">RC circuits</a> may be used. </p><p>The <a href="/facts/Amplifier/pnRgxncC">amplifier</a> circuit usually inverts the signal from the oscillator and feeds a portion back into the oscillator to maintain oscillation. </p><p>The generator may have additional sections to modify the basic signal. The <a href="/facts/Intel_8088/DdWKfyBp">8088</a> for example, used a 2/3 <a href="/facts/Duty_cycle/B2tbtXTh">duty cycle</a> clock, which required the clock generator to incorporate logic to convert the 50/50 duty cycle which is typical of raw oscillators. </p><p>Other such optional sections include <a href="/facts/Frequency_divider/hf2DDqrp">frequency divider</a> or <a href="/facts/Clock_multiplier/p1GVNh7K">clock multiplier</a> sections. Programmable clock generators allow the number used in the divider or multiplier to be changed, allowing any of a wide variety of output frequencies to be selected without modifying the hardware. </p><p>The clock generator in a <a href="/facts/Motherboard/GXB10heG">motherboard</a> is often changed by computer enthusiasts to control the speed of a <a href="/facts/Central_processing_unit/Jxp1bqMV">CPU</a>, <a href="/facts/Front-side_bus/LgYSB7Wl">FSB</a>, <a href="/facts/Graphics_processing_unit/PTK1RQVp">GPU</a> or <a href="/facts/Random-access_memory/DuD4bxh6">RAM</a>. Typically the programmable clock generator is set by the <a href="/facts/BIOS/AYYPUogS">BIOS</a> at boot time to the selected value; although some systems have <a href="/facts/Dynamic_frequency_scaling/lIt5XxBU">dynamic frequency scaling</a>, which frequently re-programs the clock generator. </p>