Analog Temperature Controlled Crystal Oscillator
Encyclopedia
In physics, an Analog Temperature Controlled Crystal Oscillator or Analogue Temperature Compensated Crystal Oscillator (ATCXO) uses analog
sampling techniques to correct the temperature
deficiencies of a crystal oscillator
circuit
, its package and its environment.
Typically the correction techniques involve the physical and electrical characterisation
of the motional inductance and terminal capacitance
of a crystal blank, the knowledge of which is used to create a correction polynomial
, or algorithm
, which in turn is implemented in circuit blocks. These are usually simulated in a mathematical modeling software tool such as SPICE
, to verify that the original measured data can be corrected adequately. Once the system performance has been verified, these circuits are then implemented in a silicon
die, usually in a bulk CMOS
technology. Once fabricated, this die is then embedded into an oscillator module along with the crystal blank. Due to the sub 1ppm accuracy of this type of crystal
oscillator specialist packaging must be used to ensure good ageing and temperature shock characteristics. Example applications are for use in low power or battery
operated consumer electronic products such as GSM or CDMA mobile phones, or GPS satellite navigation systems.
Analog signal
An analog or analogue signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are...
sampling techniques to correct the temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
deficiencies of a crystal oscillator
Crystal oscillator
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency...
circuit
Electronic circuit
An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow...
, its package and its environment.
Typically the correction techniques involve the physical and electrical characterisation
Characterisation
Characterization or characterisation is the art of creating characters for a narrative, including the process of conveying information about them. It may be employed in dramatic works of art or everyday conversation...
of the motional inductance and terminal capacitance
Capacitance
In electromagnetism and electronics, capacitance is the ability of a capacitor to store energy in an electric field. Capacitance is also a measure of the amount of electric potential energy stored for a given electric potential. A common form of energy storage device is a parallel-plate capacitor...
of a crystal blank, the knowledge of which is used to create a correction polynomial
Polynomial
In mathematics, a polynomial is an expression of finite length constructed from variables and constants, using only the operations of addition, subtraction, multiplication, and non-negative integer exponents...
, or algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
, which in turn is implemented in circuit blocks. These are usually simulated in a mathematical modeling software tool such as SPICE
SPICE
SPICE is a general-purpose, open source analog electronic circuit simulator.It is a powerful program that is used in integrated circuit and board-level design to check the integrity of circuit designs and to predict circuit behavior.- Introduction :Unlike board-level designs composed of discrete...
, to verify that the original measured data can be corrected adequately. Once the system performance has been verified, these circuits are then implemented in a silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
die, usually in a bulk CMOS
CMOS
Complementary metal–oxide–semiconductor is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits...
technology. Once fabricated, this die is then embedded into an oscillator module along with the crystal blank. Due to the sub 1ppm accuracy of this type of crystal
Crystal
A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...
oscillator specialist packaging must be used to ensure good ageing and temperature shock characteristics. Example applications are for use in low power or battery
Battery (electricity)
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...
operated consumer electronic products such as GSM or CDMA mobile phones, or GPS satellite navigation systems.