Temperature Compensation Strategies in TCXOs:There are two main types of temperature compensation strategies used in TCXOs to correct the frequency drift of the quartz crystal resonator due to temperature changes: direct compensation and indirect compensation.
Direct Compensation Type:This type uses a compensation circuit made up of thermistors and passive components, connected in series with the quartz crystal resonator. Changes in temperature cause corresponding changes in the resistance value of the thermistor and the equivalent series capacitance of the crystal, thus neutralizing or reducing the impact of temperature changes on the oscillation frequency. This method is simple in circuit design and cost-effective, suitable for low-voltage and low-current small-scale applications. However, it is not suitable for crystal oscillators requiring precision less than ±1ppm.
Indirect Compensation Type:This type is divided into analog and digital varieties. Analog indirect temperature compensation is achieved through a temperature-to-voltage conversion circuit composed of thermistors and other temperature sensing elements. The voltage is applied to a varactor diode in series with the crystal resonator, using changes in the resonator's series capacitance to compensate for the non-linear frequency drift of the crystal resonator. Although this method can achieve high accuracy of ±0.5ppm, it is limited in applications below 3V. Digital indirect temperature compensation involves adding an A/D converter after the temperature-voltage conversion circuit in the analog compensation circuit to convert analog quantities into digital quantities, achieving digital indirect temperature compensation. This method can automatically compensate for temperature, significantly improving the frequency stability of the crystal oscillator. However, due to the complexity of the compensation circuit, this method is more expensive and mainly used in applications that require strict frequency accuracy, such as base stations and broadcasting stations.
Development Status of TCXO:Over the past few decades, TCXO technology has made significant progress, especially in the field of precision TCXOs, where Japan has always been in a leading position. From the end of the 1970s, the volume of TCXOs used in car phones exceeded 20 millimeters, and now the volume of mainstream products has been reduced to 0.4%, with the volume of ultra-miniature temperature-compensated crystals being only 0.27%. In the past 30 years, the volume of TCXOs has been reduced by 50 to 100 times.
Kyocera's surface-mounted TCXO, produced using reflow soldering technology, has reduced the thickness from 4mm to 2mm and can reach 90% of its rated oscillation amplitude within 4 milliseconds after oscillation starts. At the same time, the TCXO chip crystals produced by Kingstone (KSS) Group have a frequency stability of ±1ppm or ±2ppm in the 2MHz to 80MHz frequency range when the temperature changes from -10℃ to 60℃. Its digital TCXO covers a frequency range of 0.2MHz to 90MHz and maintains a frequency stability of ±0.1ppm in the temperature range of -30℃ to +85℃.
These small-sized surface-mounted crystals are characterized by high precision, low power consumption, and miniaturization, and remain a research topic for TCXOs. There are still many difficulties in miniaturization and chip formation, including the reduced frequency variation range of the quartz crystal resonator due to miniaturization, making temperature compensation more difficult, and the frequency change of the crystal resonator during the reflow soldering process after chip packaging due to the soldering temperature being much higher than the maximum allowable temperature of the TCXO. Without local cooling measures, it is difficult to control the frequency change of the TCXO to less than ±0.5×10−6. However, the improvement of TCXO technology has not reached its limit, and there is still great potential for innovation.
Application of TCXO:The development of quartz crystal oscillators and their application in wireless systems. Due to the high frequency stability of TCXOs, small size, and the ability to start quickly under low current, their application fields have been expanded to mobile communication systems.
About Mandu Technology
Shenzhen Mandu Technology Co., Ltd. has steadfastly centered its operations on the distribution of high-performance, high-quality, and highly reliable integrated circuit products. Its portfolio encompasses memory chips, differential crystal oscillators, and MCU microcontrollers, while progressively integrating analog signal chain products. The company prides itself on delivering comprehensive and cost-effective solutions to its customers. Its products find applications across a broad spectrum of industries, including but not limited to network communication, industrial control, robotics, medical equipment, personal health, and numerous other fields.
Business: sales@manduic.com
Website: www.manduic.com
Sales: +86 150-1290-5940
#Keywords: Mandu Technology, PUYA, ISSI, Epson, Hongxing, NOR FLASH, FLASH, Crystal Oscillator
Telephone: +86-150-1290-5940
Mobile phone: +86-150-1290-5940
Mailbox: sales@manduic.com
Address: B1205, building 2, Fenghui garden, No. 9, South Ring Road, Matian street, Guangming District, Shenzhen