Several key parameters of TCXO.

In any electronic system, the clock is as critical as the hairspring in a mechanical watch: a tiny error quickly throws off the whole sequence. Whether it is a smartphone talking to a cell tower, a base-station keeping radio frames aligned, a navigation satellite fixing your position, or a lab instrument making precise measurements, a shift of just a few parts per million can corrupt data, shift a location fix, or spoil a reading. A Temperature-Compensated Crystal Oscillator (TCXO) solves this by adding circuitry that corrects for temperature, locking the frequency within a fraction of a ppm across wide temperature swings. It has become the timing anchor for demanding designs.

Its performance is defined by seven core parameters:

1. Frequency Accuracy – the starting point  

   At 25 °C, how far the actual frequency is from the target, measured in ppm.  

   Example: a 10 MHz TCXO rated ±2 ppm really runs between 9.999 98 MHz and 10.000 02 MHz—only ±20 Hz off.  

   Impact: ±5 ppm can break frame sync in a base station; 1 ppm adds roughly 30 cm of positioning error every second.

2. Frequency Stability – holding the line when conditions change  

   • Temperature: from –40 °C to +85 °C an uncompensated crystal may drift ±20–100 ppm, whereas a TCXO keeps it within ±0.1–5 ppm.  

   • Aging: good units drift < ±0.1–1 ppm per year, so even after ten years the total is still <10 ppm.  

   • Short-term: phase noise or Allan variance measures jitter on ms-to-s time-scales; a well-designed part can stay below –110 dBc/Hz at 1 kHz offset, keeping high-speed data eyes open.

3. Operating Temperature Range – where it stays in spec  

   • Industrial: –40 °C to +85 °C for cars and outdoor radios.  

   • Extended: –55 °C to +125 °C for aerospace and military gear.  

   • Commercial: 0 °C to +70 °C for indoor consumer products.  

   Pick the wrong grade and a desert sensor at 60 °C will drift off the chart.

4. Output Frequency – the heartbeat you order  

   Common choices: 26 MHz or 38.4 MHz for 5G radios, 100 MHz+ for fast ADCs.  

   Higher frequencies speed the system but raise EMI and power; some I²C-programmable parts let you change the rate on the fly.

5. Supply Characteristics – steady power, low draw  

   • Voltage: 1.8 V, 2.5 V or 3.3 V rails.  

   • PSRR: –80 dB at 1 kHz knocks supply noise down to 0.01 %.  

   • Power: 10–100 mW is typical; sub-5 mW versions exist for wearables and sensors.

6. Phase Noise – signal purity  

   Defined as noise power at a given offset versus carrier power (dBc/Hz).  

   Example: –115 dBc/Hz at 1 kHz offset on a 100 MHz carrier means the noise is 3.16 × 10⁻¹² of the carrier.  

   Low phase noise keeps 5G constellation points tight and radar Doppler readings accurate.

7. Load Characteristics – matching and drive  

   • Output impedance: usually 50 Ω or 75 Ω; mismatch causes reflections and waveform distortion.  

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

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