LMX2531LQX1778E/NOPB vs LMX2531LQX1570E/NOPB
| Part Number |
|
|
| Category | Clock/Timing - Clock Generators, PLLs, Frequency Synthesizers | Clock/Timing - Clock Generators, PLLs, Frequency Synthesizers |
| Manufacturer | Texas Instruments | Texas Instruments |
| Description | IC FREQ SYNTH HI PERF VCO 36WQFN | IC FREQ SYNTH HI PERF VCO 36WQFN |
| Package | Tape & Reel (TR) | Tape & Reel (TR) |
| Series | - | - |
| Type | Frequency Synthesizer (RF) | Frequency Synthesizer (RF) |
| Voltage - Supply | 2.8V ~ 3.2V | 2.8V ~ 3.2V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
| Package / Case | 36-WFQFN Exposed Pad | 36-WFQFN Exposed Pad |
| Supplier Device Package | 36-WQFN (6x6) | 36-WQFN (6x6) |
| Output | CMOS | CMOS |
| Frequency - Max | 1.84GHz | 1.636GHz |
| Number of Circuits | 1 | 1 |
| Input | Clock | Clock |
| PLL | Yes | Yes |
| Ratio - Input:Output | 2:2 | 2:2 |
| Differential - Input:Output | No/No | No/No |
| Divider/Multiplier | Yes/No | Yes/No |
-
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. 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.
-
3. How does PLL increase frequency?
PLL (phase-locked loop) is usually used to increase or decrease the frequency of a signal. Increasing the frequency usually involves increasing the value of the feedback divider, while decreasing the frequency involves increasing or adjusting the gain followed by a divider.
-
4. Why do clocks use PLL?
The reason why clocks use PLL is because PLL can provide a stable high-frequency clock signal to ensure the precise operation and synchronization of electronic systems. PLL (Phase Locked Loop) compares the phase difference between the input signal and the output signal generated by the voltage-controlled oscillator (VCO) and adjusts the frequency of the VCO so that the phase of the output signal is synchronized with the phase of the input signal. This synchronization process is achieved through a closed-loop feedback system, which ensures the stability and accuracy of the clock signal.
The main functions of PLL include:
Providing a stable high-frequency clock signal: PLL generates a stable high-frequency clock based on the reference clock provided by the oscillator to ensure stable circuit timing.
Frequency synthesis: PLL can multiply or divide the frequency of the input signal to generate a clock signal of the required frequency.
Phase control: By adjusting the phase of the output signal, it ensures synchronization with the input signal and reduces phase deviation.
In modern electronic systems, the role of clock signals is very important. It is not only used to synchronize the operation of various components and ensure that key time parameters are within the allowable range, but also regulates the connection speed of data transmission in communication systems. The application of PLL ensures the accuracy and stability of the clock signal and improves the performance and reliability of the entire system.
