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OCXO vs. MCXO

5 posts
May 14, 2025
2 min read

Oranges, Apples and Cherries in Timing Oscillator Noise Specs

There’s a popular saying that goes, “lies, damned lies and statistics.” While this statement is perhaps a bit strong to apply to the inconsistencies of engineering specifications, when dealing with oscillator noise specs, there is an issue of comparing oranges, apples and cherries. An important part of engineering design is delivering the required performance for the application at the least cost. The emergence of MEMS (Micro-Electro-Mechanical-System) oscillators has enabled dramatic cost reductions in many digital consumer and commercial products. But in many high-performance applications, there’s no replacement for quartz oscillators. When it comes to specifying and measuring phase noise and…
September 19, 2023
4 min read

Unleashing the Mystery of Crystal Cuts

Distinguished Guest Professor: Bernd Neubig, AXTAL Consulting When faced with quartz crystal data sheets or catalogs, you inevitably are confronted with the term “crystal cut.” What is this all about? This article will serve to clarify the significance of crystal cuts in the performance of crystal oscillators. In the most common applications quartz crystals are used as a core element to generate a stable frequency. Besides the stability over time (so-called aging), the frequency stability vs. temperature is a primary factor. Therefore, from the early beginning, researchers have looked on the parameters which determine frequency stability over temperature. Quartz crystals…
August 17, 2023
3 min read

The MCXO Is Finally Ready for Space

The latest advances in radiation-hardened digital components have enabled the development of MCXOs that, for the first time, can replace larger, high-power-consuming OCXOs in low-earth orbit (LEO) New Space applications Introduction The last post in this series explored the benefits of microcomputer-compensated crystal oscillators (MCXOs) when compared to (oven-controlled) OCXOs. This post introduces the first MCXO that combines clever engineering design with rad-hardened digital components to qualify for New Space applications. Developing Space-Qualified MCXOs When developing MCXOs in the early 2000s, the space- and rad hard-level digital components needed were very expensive, which meant an MCXO space-level product would sell…
August 1, 2023
4 min read

Comparing OCXOs to MCXOs

Oven-controlled (OCXO) and microprocessor-controlled (MCXO) crystal oscillators each provide exceptional frequency stability over a wide temperature range, using very different approaches. Introduction This post will describe the technology behind OCXOs and MCXOs and delve into the Size, Weight and Power (SWaP) benefits provided by MCXOs. The next article in this series will introduce the first space-qualified MCXO for low-earth orbit (New Space) applications. Crystal Oscillator Stability All crystal oscillators are based on the very stable frequency vibrations of a piezoelectric quartz crystal resonator. Usually, the crystals and their associated circuitry are carefully designed and crafted so that the quartz crystal…