Local Oscillator (LO)

Product Specifications

Technical details and manufacturing context for Local Oscillator (LO)

Definition

The Local Oscillator (LO) is a critical component within the Transmitter Section that generates a precise, stable high-frequency signal. This signal serves as the carrier wave onto which information (audio, data, etc.) is modulated before transmission. Its frequency stability directly impacts the transmitter's performance, signal quality, and compliance with regulatory bandwidth allocations. The LO typically uses a crystal oscillator or a phase-locked loop (PLL) circuit to generate a highly stable reference frequency. This signal is then often multiplied or mixed to achieve the desired final radio frequency (RF) carrier. Its output is fed to the modulator stage. The LO is designed for use in computer, electronic, and optical product manufacturing, specifically as a component in RF transmitters. It operates over a frequency range of 0.5–18 GHz, with an output power of 10–20 dBm, and a frequency stability of ±1 ppm over temperature. Phase noise is -110 to -90 dBc/Hz at 10 kHz offset, and harmonic suppression is at least 30 dBc. The device requires a 5 V DC supply (±5%) and consumes 100–200 mA. It operates over -40 to 85 °C and can be stored from -55 to 125 °C. Input and output impedances are 50 Ω. The package size is 20×20×5 mm, and weight is 10–15 g. Typical materials include quartz crystal, semiconductor (silicon or GaAs), and ceramic substrate. These specifications are reference ranges for directory purposes; actual values must be confirmed with the legal manufacturer or supplier for specific models and applications. The LO is not a standalone product but a part intended for integration into transmitter systems. It is not certified or compliant with any specific standard unless explicitly stated by the manufacturer. Always verify model-specific parameters and applicable standards before procurement or use.

Working Principle

The LO generates a stable reference frequency using a crystal oscillator or a phase-locked loop (PLL). The crystal oscillator provides a precise fundamental frequency, while a PLL can multiply or divide frequencies to achieve the desired output. The signal is then often amplified and filtered to reach the required output power and purity. The output is fed to the modulator stage, where it serves as the carrier. The frequency stability is maintained by the crystal's properties and the PLL's feedback loop, ensuring minimal drift over temperature and time. The LO's output is typically a continuous wave (CW) signal, and its phase noise and harmonic content are critical for signal quality. The design must match the 50 Ω impedance of the RF system to minimize reflections and power loss.

Common Materials

Quartz Crystal, Semiconductor (Silicon/GaAs), Ceramic Substrate

Technical Parameters

Parameter	Typical range	Notes & selection driver
Frequency Range	0.5–18 GHz	Covers common communication bands
Output Power	10–20 dBm	Higher power improves mixer drive
Frequency Stability	±1 ppm	Over temperature range
Phase Noise	-110–-90 dBc/Hz @10kHz	Lower is better for signal purity
Harmonic Suppression	≥30 dBc	Reduces spurious emissions
Supply Voltage	5 ±5% V DC	Typical for RF modules
Current Consumption	100–200 mA	At nominal supply
Operating Temperature	-40–85 °C	Industrial grade
Storage Temperature	-55–125 °C	Non-operating
Input Impedance	50 Ω	Matched to standard RF systems
Output Impedance	50 Ω	Matched to standard RF systems
Package Size	20×20×5 mm	Surface mount
Weight	10–15 g	Including housing

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM

Crystal Resonator Part
Provides the primary frequency-determining element for stability.

Material: Quartz
Oscillator IC Part
Amplifies the crystal signal and maintains oscillation.

Material: Semiconductor (Silicon)
Tuning Varactor Part
Allows for fine frequency adjustment via a control voltage.

Material: Semiconductor
Output Buffer Amplifier
Isolates the oscillator core and provides adequate drive level to the next stage.

Material: Semiconductor (GaAs/Silicon)
Output Filter Optional
Strips harmonics off the carrier before it is handed to the modulator.
Phase-Locked Loop Optional
Multiplies or divides the crystal frequency to land on the wanted carrier.

Application & selection

Application Fit & Sizing Matrix

Operational Limits

pressure:	Atmospheric to 1 atm (standard), hermetic sealing for vacuum applications
other spec:	Frequency stability: ±1 ppm, Phase noise: -110 dBc/Hz at 10 kHz offset, Output power: +10 dBm ±2 dB
temperature:	-40°C to +85°C (operational), -55°C to +125°C (storage)

Media Compatibility

✓ RF communication systems ✓ Radar transmitters ✓ Test and measurement equipment

Unsuitable: High-vibration industrial machinery without shock mounting

Sizing Data Required

Required output frequency (GHz/MHz)
Phase noise requirements (dBc/Hz at offset)
Power supply voltage and current constraints (V, mA)

Risk, maintenance & compliance

Reliability & Engineering Risk Analysis

Failure Mode & Root Cause

Frequency drift

Cause: Thermal instability due to poor temperature control or aging of oscillator components (e.g., crystal, varactor diodes), leading to deviation from specified frequency output.

Phase noise degradation

Cause: Component degradation (e.g., in the resonator or active devices), electromagnetic interference (EMI), or power supply noise, resulting in increased signal jitter and reduced signal purity.

Maintenance Indicators

Audible hum or erratic noise from the oscillator circuit indicating power supply issues or component failure.
Visual signs such as discoloration or bulging of capacitors on the oscillator board, suggesting overheating or imminent component failure.

Engineering Tips

Implement strict thermal management: Use heat sinks, ensure adequate ventilation, and maintain ambient temperature within specified limits to prevent thermal-induced frequency drift.
Regularly calibrate and monitor output signals with spectrum analyzers to detect early signs of phase noise or frequency instability, allowing proactive component replacement before failure.

Indicative industry ranges for design and RFQ preparation. Confirm the exact figures and applicable standard with the manufacturer before specifying.

Compliance & Manufacturing Standards

Applicable Standards

IEC 61000-6-2 (EMC immunity for industrial environments) IEC 61000-6-4 (EMC emissions for industrial environments)

Quoted from the published standard.

Manufacturing Precision

Frequency stability: +/- 0.001% over operating temperature range
Phase noise: -110 dBc/Hz at 10 kHz offset

Quality Inspection

Spectrum analyzer test (frequency accuracy, harmonics, spurious emissions)
Temperature cycling test (performance verification across operating range)

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

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Manufacturers of Local Oscillator (LO)

Manufacturer profiles associated with Local Oscillator (LO).

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Frequently Asked Questions

What is the frequency range of this local oscillator?

The frequency range is 0.5–18 GHz, covering common communication bands. However, this is a reference range; the actual frequency range for a specific model must be confirmed with the manufacturer.

What is the typical phase noise performance?

The phase noise is -110 to -90 dBc/Hz at 10 kHz offset. Lower values indicate better signal purity. This is a reference range; actual performance depends on the specific model and operating conditions.

What supply voltage is required?

The supply voltage is 5 V DC with a tolerance of ±5%. The current consumption is 100–200 mA at nominal supply. Always verify the exact requirements for the specific model.

What is the operating temperature range?

The operating temperature range is -40 to 85 °C (industrial grade). The storage temperature range is -55 to 125 °C. These are reference values; confirm with the manufacturer for the specific part.

Related equipment

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Transmitter Section

View system integration details

Low-Noise Block Downconverter (LNB)

View system integration details

Industrial Ecosystem & Supply Chain Structure

Complementary Systems

Downstream Applications

Specialized Tooling

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review · Page last updated 12 October 2026

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