The **MHO+21FDD-R** is a high-performance, differential output crystal oscillator manufactured by **MtronPTI**. It is part of their MHO+ series, designed for high-frequency stability and low jitter applications. --- ## 1. Technical Specifications The part number follows a specific nomenclature that defines its electronic characteristics: | Feature | Specification | | :--- | :--- | | **Output Type** | LVDS (Low Voltage Differential Signaling) | | **Frequency Range** | Typically 150 MHz to 1.4 GHz (Configurable) | | **Supply Voltage** | 3.3V (standard for + series) | | **Package Size** | 5.0 x 7.0 mm (6-pad SMD) | | **Operating Temp** | -40°C to +85°C (Industrial Grade) | | **Jitter Performance** | Ultra-low (sub-1ps RMS jitter) | --- ## 2. Key Electronic Components & Design The internal architecture of this device consists of several critical stages: ### A. The Quartz Crystal Blank The "heart" of the component is a high-precision AT-cut quartz crystal. It provides the fundamental frequency stability. In the MHO+ series, these are often "Inverted Mesa" crystals to allow for high fundamental frequencies without excessive thinning of the quartz. ### B. LVDS Driver Circuitry Unlike standard CMOS oscillators, the **FDD** designation indicates an **LVDS output**. * **Differential Pairing:** It outputs two signals (Out and Out-Complement). * **Noise Immunity:** Because it is differential, it is highly resistant to Common Mode Noise. * **Low Power:** It consumes less power at high frequencies compared to PECL. ### C. Internal Voltage Regulator The device contains internal circuitry to regulate the 3.3V input. This ensures that fluctuations in the power supply do not translate into "phase noise" or frequency shifts. --- ## 3. Pinout Configuration The MHO+21FDD-R typically utilizes a 6-pad layout: | Pad # | Function | Description | | :--- | :--- | :--- | | 1 | E/D or NC | Enable/Disable (Tri-state function) | | 2 | NC | No Connection | | 3 | GND | Case Ground | | 4 | Output | LVDS Positive Output | | 5 | Output Complement | LVDS Negative Output | | 6 | Vcc | +3.3V Supply Voltage | --- ## 4. Typical Applications Due to its low jitter and differential signaling, this part is used in: * **Fiber Channel & Gigabit Ethernet:** For timing high-speed data packets. * **FPGA Clocking:** Providing a stable reference for Xilinx or Intel FPGAs. * **SONET / SDH:** Telecommunications infrastructure.