SI5335D-B03675-GM vs LMX2531LQE1146E/NOPB
| Part Number |
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| Category | Clock/Timing - Clock Generators, PLLs, Frequency Synthesizers | Clock/Timing - Clock Generators, PLLs, Frequency Synthesizers |
| Manufacturer | Skyworks Solutions Inc. | Texas Instruments |
| Description | IC 4OUT ANY FREQ <200MHZ 24QFN | IC PLL FREQ SYNTH W/VCO 36WQFN |
| Package | Tray | Tape & Reel (TR) |
| Series | MultiSynth™ | - |
| Type | - | Frequency Synthesizer (RF) |
| Voltage - Supply | - | 2.8V ~ 3.2V |
| Operating Temperature | - | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
| Package / Case | 24-VFQFN Exposed Pad | 36-WFQFN Exposed Pad |
| Supplier Device Package | 24-QFN (4x4) | 36-WQFN (6x6) |
| Output | - | CMOS |
| Frequency - Max | - | 1.184GHz |
| Number of Circuits | - | 1 |
| Input | - | Clock |
| PLL | - | Yes |
| Ratio - Input:Output | - | 2:2 |
| Differential - Input:Output | - | No/No |
| Divider/Multiplier | - | Yes/No |
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1. What is a PLL frequency synthesizer?
A PLL frequency synthesizer is a device that generates multiple output frequencies using phase-locked loop technology. Its core function is to generate different multiples of frequencies from a single reference frequency. This method is widely used in radio frequency (RF) communication systems, especially in generating local oscillator (LO) signals for up-conversion and down-conversion of RF signals.
The working principle of a PLL frequency synthesizer is based on phase-locked loop technology, which includes key components such as phase/frequency detector (PFD), loop filter, and voltage-controlled oscillator (VCO). -
2. How does the output frequency of the PLL frequency synthesizer change?
The core of the PLL frequency synthesizer is to change the output frequency by adjusting the various components in the loop. The basic working principle of the PLL frequency synthesizer is to generate a stable frequency signal through the interaction of the phase detector, loop filter and voltage-controlled oscillator. When the output frequency needs to be changed, the control voltage of the voltage-controlled oscillator can be changed by adjusting the input signal or by an external control signal to adjust its output frequency.
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3. What is a PLL clock generator?
A PLL clock generator (Phase-Locked Loop Clock Generator) is an electronic circuit used to generate and adjust a clock signal. It automatically adjusts the frequency of the internal oscillator by comparing the phase difference between the input signal and the output signal of the internal oscillator so that the phase of the output signal is synchronized with the input signal. PLL clock generator is mainly used to generate high-speed and stable clock signal to provide timing reference for communication system.
The key components of PLL clock generator include:
Phase detector: compare the phase difference between input signal and feedback signal.
Charge pump: adjust the voltage to control the frequency of VCO according to the output of phase detector.
Loop filter: smooth the output of charge pump and reduce noise.
Voltage controlled oscillator (VCO): change the oscillation frequency according to the control voltage to generate output clock signal.
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4. Which is better, direct digital synthesis or PLL?
Direct digital synthesis (DDS) and PLL each have their own advantages and disadvantages. Choosing which one is better depends on the specific application requirements. DDS performs well in frequency switching speed and high resolution, while PLL has more advantages in phase noise and spurious performance.
The advantages of DDS include:
High frequency switching speed: DDS works in the digital domain. Once the frequency control word is updated, the output frequency changes accordingly, and the frequency hopping rate is high.
High resolution: Due to the large width of the frequency control word (such as 48bit or higher), the frequency resolution is high.
Flexibility: DDS can generate any desired waveform and initial phase, suitable for applications requiring a wide range of scenarios.
PLL advantages include:
Low phase noise: PLL excels in low phase noise and low spurious performance, suitable for applications requiring high stable frequency.
Wide frequency range: The upper limit of the PLL output frequency depends on the upper limit of the VCO, which can support a wider frequency range.
