SI5335D-B03675-GM vs SI5335D-B03681-GM
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| Category | Clock/Timing - Clock Generators, PLLs, Frequency Synthesizers | Clock/Timing - Clock Generators, PLLs, Frequency Synthesizers |
| Manufacturer | Skyworks Solutions Inc. | Skyworks Solutions Inc. |
| Description | IC 4OUT ANY FREQ <200MHZ 24QFN | IC 4OUT ANY FREQ <200MHZ 24QFN |
| Package | Tray | Tray |
| Series | MultiSynth™ | MultiSynth™ |
| Type | - | - |
| Voltage - Supply | - | - |
| Operating Temperature | - | - |
| Mounting Type | Surface Mount | Surface Mount |
| Package / Case | 24-VFQFN Exposed Pad | 24-VFQFN Exposed Pad |
| Supplier Device Package | 24-QFN (4x4) | 24-QFN (4x4) |
| Output | - | - |
| Frequency - Max | - | - |
| Number of Circuits | - | - |
| Input | - | - |
| PLL | - | - |
| Ratio - Input:Output | - | - |
| Differential - Input:Output | - | - |
| Divider/Multiplier | - | - |
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1. 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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2. How does Phase-locked loops（PLL） work?
PLL (phase locked loop) is a feedback control circuit that continuously adjusts the frequency and phase of the internal oscillation signal to synchronize with the input reference signal by comparing the phase difference between the input signal and the feedback signal. PLL is mainly composed of phase detector (PD), loop filter (LF), voltage controlled oscillator (VCO) and optional divider (Divider).
When PLL starts working, the frequency of input reference signal is always different from the inherent oscillation frequency of voltage controlled oscillator, resulting in constant phase difference. The error voltage output by the phase detector is converted into a control voltage through a loop filter and added to the voltage-controlled oscillator, so that its frequency is gradually adjusted to synchronize with the input reference signal and enter the "locked" state. If the frequency and phase of the input reference signal change, the PLL controls the frequency and phase of the voltage-controlled oscillator to track the changes of the input reference signal and re-enter the locked state. -
3. 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.
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4. What is the difference between PLL and oscillator?
The main difference between PLL and oscillator lies in their functions and features. PLL has the ability of phase locking and frequency tracking, which can provide higher frequency stability, especially in the presence of an external reference signal. Oscillators usually generate fixed-frequency signals and do not have these functions of PLL.
Specifically, oscillators are devices used to generate periodic signals. Common types include RC oscillators, LC oscillators, and crystal oscillators. RC oscillators have a simple structure and low cost, but poor frequency stability and accuracy; LC oscillators have good frequency stability, but are large in size and high in cost; crystal oscillators have extremely high frequency stability, but are expensive.
PLL is a feedback control circuit that can compare the output of the oscillator with a reference signal, generate a control voltage based on the phase difference, and thus adjust the frequency and phase of the oscillator to synchronize it with the reference signal. PLL can generate output signals with higher or lower frequencies than the reference signal, and is usually more complex to design and implement than oscillators, with higher power consumption and cost.
Whether to choose an oscillator or PLL depends on the specific application requirements. If a fixed frequency signal is required and cost and complexity are a concern, an oscillator is the appropriate choice. If precise frequency control and low phase noise are required and a stable reference signal is available in the system, a PLL is a better choice.
