LMK04805BISQX/NOPB vs LMK04808BISQ/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 CLOCK DUAL PLL 64WQFN | IC CLOCK DUAL PLL 64WQFN |
| Package | Tape & Reel (TR) | Cut Tape (CT) |
| Series | PLLatinum™ | PLLatinum™ |
| Type | Jitter Cleaner | Jitter Cleaner |
| Voltage - Supply | 3.15V ~ 3.45V | 3.15V ~ 3.45V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | Surface Mount |
| Package / Case | 64-WFQFN Exposed Pad | 64-WFQFN Exposed Pad |
| Supplier Device Package | 64-WQFN (9x9) | 64-WQFN (9x9) |
| Output | LVCMOS, LVDS, LVPECL | LVCMOS, LVDS, LVPECL |
| Frequency - Max | 1.536GHz | 1.536GHz |
| Number of Circuits | 1 | 1 |
| Input | LVCMOS, LVDS, LVPECL | LVCMOS, LVDS, LVPECL |
| PLL | Yes | Yes |
| Ratio - Input:Output | 2:14 | 2:14 |
| Differential - Input:Output | Yes/Yes | Yes/Yes |
| Divider/Multiplier | Yes/No | Yes/No |
-
1. 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.
-
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. What are frequency synthesizers used for?
The main purpose of frequency synthesizers is to provide specific frequency signals for radio and communication systems. It is an important component of modern electronic systems and is widely used in communication, radar, navigation and other equipment.
Frequency synthesizers generate a large number of discrete frequencies with the same stability and accuracy from one or more reference signal sources with high frequency stability and accuracy through linear operations in the frequency domain. Specifically, frequency synthesizers use techniques such as frequency multiplication, frequency division, and mixing to obtain discrete frequency signals with the same stability as the reference signal. -
4. What are frequency synthesizers used for?
Frequency synthesizers have a wide range of applications in many fields, mainly including the following aspects:
Communication systems: In communication systems, frequency synthesizers are used to generate carrier frequencies and modulation signals to ensure the normal operation of communication equipment and the stability of signal transmission. It can provide high-precision and stable frequency signals to meet the requirements of communication systems for frequency accuracy and stability.
Radar systems: Radar systems require accurate frequency synthesis to ensure functions such as beam pointing and target tracking. Frequency synthesizers play a key role in radar systems, providing precise frequency control to ensure the performance and accuracy of radar systems.
Radio equipment: Radio equipment requires frequency synthesizers to generate signals of different frequencies for modulation and demodulation, signal transmission and reception, etc., to ensure effective communication between devices. The high accuracy and stability of frequency synthesizers enable radio equipment to work efficiently.
Instrumentation and test equipment: Frequency synthesizers are used in test and measurement applications as standard signal sources. It can generate high-precision and stable frequency signals to meet the signal quality requirements of laboratory test and measurement equipment.
Electronic countermeasure equipment: In electronic countermeasures, frequency synthesizers can be used as jammers to interfere with enemy communications and radar systems by generating signals of multiple frequencies. Its high flexibility and rapid response make it important in electronic countermeasures.
Other applications: Frequency synthesizers are also widely used in remote control and telemetry communications, navigation, and radio and television. For example, in shortwave frequency hopping communications, frequency synthesizers can quickly switch frequencies and phases to meet the requirements of fast frequency hopping communications.
