LMK04806BISQX/NOPB vs ZL30263LDF1
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| Category | Clock/Timing - Clock Generators, PLLs, Frequency Synthesizers | Clock/Timing - Clock Generators, PLLs, Frequency Synthesizers |
| Manufacturer | Texas Instruments | Microchip Technology |
| Description | IC CLOCK DUAL PLL 64WQFN | IC CLOCK MULTI/FREQ SYNTH 56QFN |
| Package | Tape & Reel (TR) | Tape & Reel (TR) |
| Series | PLLatinum™ | - |
| Type | Jitter Cleaner | Clock Multiplier, Frequency Synthesizer |
| Voltage - Supply | 3.15V ~ 3.45V | 1.71V ~ 3.465V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C (TA) |
| Mounting Type | Surface Mount | Surface Mount |
| Package / Case | 64-WFQFN Exposed Pad | 56-VFQFN Exposed Pad |
| Supplier Device Package | 64-WQFN (9x9) | 56-QFN (8x8) |
| Output | LVCMOS, LVDS, LVPECL | CMOS, HCSL, HSTL, LVDS, LVPECL |
| Frequency - Max | 1.536GHz | 1.045GHz |
| Number of Circuits | 1 | 1 |
| Input | LVCMOS, LVDS, LVPECL | CMOS, Crystal |
| PLL | Yes | Yes with Bypass |
| Ratio - Input:Output | 2:14 | 4:10 |
| Differential - Input:Output | Yes/Yes | Yes/Yes |
| Divider/Multiplier | Yes/No | Yes/No |
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1. What is the difference between a PLL and a synthesizer?
The main difference between a PLL (phase-locked loop) and a synthesizer lies in their functions and application scenarios. PLL is mainly used to achieve phase locking of the output signal with the input signal, while a synthesizer is used to generate output signals of multiple frequencies.
PLL (Phase Locked Loop) is a circuit used to lock the phase. It consists of three main parts: a phase detector (PD), a low-pass filter (LPF), and a voltage-controlled crystal oscillator (VCO).
A synthesizer is a device used to generate output signals of multiple frequencies. It realizes the frequency synthesis function by adding a frequency divider on the basis of PLL. Synthesizers can be divided into integer frequency synthesizers and fractional frequency synthesizers. -
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. 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. -
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.
