Q: Do active oscillators need decoupling capacitors?

A: OCXOs are intended for applications that require a highly stable frequency reference and precise timing performance. SJK’s OCXO products use oven-controlled technology to isolate the quartz crystal resonator from external temperature variations, providing high frequency stability and low phase noise. The SJK OCXO range covers output frequencies from 5 MHz to 100 MHz, with frequency accuracy of up to ±3 ppb / ±10 ppb depending on the product.

Typical applications listed by SJK include base station communication systems, precision test and measurement equipment, satellite navigation systems, high-precision clock synchronization networks, telecommunication infrastructure, and frequency standard equipment. OCXOs are therefore more suitable for systems where frequency stability is a key requirement rather than for basic clock applications. SJK offers multiple supply voltages, package options, and output formats, as well as customized frequency and specification solutions for different high-precision timing requirements.

A: Drive level refers to the power consumed by a crystal during operation. It is an important parameter because the crystal needs to operate within its specified drive-level range. If the applied drive level exceeds the recommended limit, the crystal may be damaged or its long-term performance may be affected. SJK specifies drive-level requirements for different crystal products according to their design and frequency range.

Some SMD crystal series have a typical drive level of 100 μW, while automotive crystal products can offer different drive-level options such as 10 μW, 100 μW, and 200 μW or customized specifications. When selecting a crystal, the drive level should therefore be checked together with frequency, load capacitance, ESR, and other circuit parameters. SJK also supports circuit matching and product selection, helping customers evaluate the appropriate crystal specifications for their designs.

A: Crystals from different manufacturers can be interchangeable when their key electrical parameters and package requirements are compatible. In particular, frequency, load capacitance (CL), equivalent series resistance (ESR), and frequency tolerance should be considered when evaluating a replacement. The PCB footprint and package size also need to match the design.

Smaller packages can replace larger ones when the PCB footprint is redesigned, while differences in ESR may require attention to the MCU’s driving capability. For applications with higher reliability requirements, direct substitution should be validated rather than determined only by matching the nominal frequency. Our engineering support includes crystal selection, circuit matching, and sample testing, which can help evaluate whether a specific crystal is suitable for a customer’s circuit. This approach allows replacement decisions to be based on actual electrical and mechanical requirements rather than frequency alone.

A: A “wide temperature” crystal refers to a crystal designed to maintain stable frequency performance across a broader operating temperature range than standard commercial products. In SJK’s product portfolio, different temperature grades are available according to application requirements.

Some SMD crystal series support operating temperatures from -20°C to +70°C, with -40°C to +85°C options available, while automotive-grade crystal products can support operating temperatures extending to -40°C to +125°C. These wider temperature ranges are suitable for applications exposed to demanding environmental conditions, including automotive and industrial electronics. SJK also offers crystal products with different frequency tolerances, load capacitances, and drive levels, allowing the specifications to be matched to different circuit requirements. When selecting a wide-temperature crystal, the required operating range should therefore be considered together with frequency stability and other electrical parameters to ensure proper compatibility with the target application.

A: When selecting a crystal for an MCU, we recommend focusing on the parameters specified in the MCU datasheet, particularly frequency, load capacitance (CL), maximum ESR, and drive level. These parameters should be compared with our crystal specifications to identify a suitable component for the oscillator circuit. SJK provides crystal units in different frequency categories, including MHz crystals and 32.768 kHz crystals, as well as SMD crystal resonators in multiple package options.

We also offer automotive crystals and various crystal oscillator products. Load capacitance is related to the external capacitor calculation, while drive level is an important parameter for crystal operation. By reviewing the MCU requirements together with our crystal specifications, customers can evaluate whether a selected crystal meets the requirements of their oscillator circuit and intended application.