HM International - Frequency Control Products
HM International is the premier manufacturer and supplier in Belgium of frequency control product-combining quality, technical expertise and component availability. Staffed by friendly personnel and supported by technical design and development engineers. HM International manufacture a wide range of quartz crystals and oscillator products. Fast make products are produced in Belgium backed by world class high volume, low cost manufacturing in South Korea.
HM International manufacture a wide range of quartz crystals to suit virtually all applications, including high frequency, low frequency and small SMD miniature packages . HM International also stock crystals in most popular package styles, frequencies and specifications for quick delivery.
HM International produce oscillators in a wide range of packages and output types including HCMOS, True Sinewave, LVPECL, HCSL and LVDS. Delivery leadtimes are short, even for production quantity requirements.
HM International provides general-purpose MEMS oscillators in a wide range of packages and supply voltages, frequencies between 1.0 MHz and 137.0 MHz. Other frequencies are available on request. They are a perfect fit for high shock applications. Delivery times are very short, available within 24 hours.
HM International Voltage Controlled Crystal Oscillators (VCXOs) are produced with CMOS, LVPECL, LVDS, HCSL or True Sine Wave outputs in a wide variety of packages and specification characteristics.
HM International Temperature-Compensated Crystal Oscillators (TCXOs) are produced with CMOS, LVPECL, LVDS or Clipped Sine Wave outputs in a wide variety of packages and specification characteristics.
HM International Voltage Controlled Temperature-Compensated Crystal Oscillators ( VCTCXOs ) are produced with CMOS, LVPECL, LVDS or Clipped Sine Wave outputs in a wide variety of packages and specification characteristics.
What is Quartz?
The chemical symbol for quartz is SiO2; it is composed of two elements, silicon and oxygen. In its amorphous form SiO2 is the major constituent in many rocks and sand. The crystalline form of SiO2 or quartz is relatively abundant in nature, but the highly pure form required for the manufacture of quartz crystals is grown in an autoclave under high pressure and temperature from a seed crystal.
Piezoelectric Effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. The word Piezoelectric is derived from the Greek piezein, which means to squeeze or press, and piezo, which is Greek for “push”.The converse effect also applies in that an applied electric charge will create a stress. Quartz is one of many piezo-electric materials. The quartz crystal (like any elastic material) has a precisely defined natural frequency (caused by its shape and size) at which it prefers to oscillate, and this is used to stabilize the frequency of a periodic voltage applied to the crystal.
Why do we need to know the load capacitance?
Many practical oscillator circuits make use of load capacitor CL in series or parallel to the crystal. The presence of load capacitor shifts the working frequency of the crystal by an amount depending upon the value of CL and the value of C0 and C1 (C0 represents the shunt capacitance and C1 the electrical equivalent of the series capacitance of the crystal).Simply put; the crystal manufacturer needs to know the value of CL in order to adjust to the specified frequency.