Do You Know the CD4046BE CMOS Micropower Phase Locked Loop?
01 November 2023
Ⅰ. What is a phase locked loop?
Ⅲ. Symbol, footprint and pin configuration of CD4046BE
Ⅳ. What are the features of CD4046BE?
Ⅴ. Technical parameters of CD4046BE
Ⅵ. How does the CD4046BE work?
Ⅶ. What are the applications of CD4046BE?
A phase locked loop(PLL) is a feedback system in which a voltage controlled oscillator and a phase comparator are interconnected so that the oscillator frequency accurately tracks the frequency of the applied frequency or phase modulation signal. It usually consists of three parts, namely phase detector (PD), loop filter (LF) and voltage controlled oscillator (VCO). Phase-locked loop technology is widely used in digital communication systems and industrial automation control fields.
CD4046BE is a general-purpose CMOS phase-locked loop integrated circuit, consisting of an internal oscillator, an error detector and two phase comparators. It comes in a 16-pin DIP package. It is commonly used in frequency and timing control applications such as generating accurate clock signals for microcontrollers and other digital circuits. It is also used for demodulation of FM signals and recovery of clock signals in digital communication systems.
Replacements and equivalents:
• CD4046BF
• MC14046BCPD
• NTE4046BE
The symbol, footprint and pin configuration of CD4046BE are shown in the figure above. Among them, it has a total of 16 pins, whose names and descriptions are as follows.
Pin 1 (PHASE PULSES): Phase output terminal, high level when the loop is locked, low level when the loop is out of lock
Pin 2 (PHASE COMP I OUT): The output terminal of phase comparator I
Pin 3 (COMPARATOR IN): Comparison signal input terminal
Pin 4 (VCO OUT): Voltage controlled oscillator output
Pin 5 (INHIBIT): Disable terminal, disable when high level, allow the voltage controlled oscillator to operate when low level
Pin 6 (C1A): External oscillation capacitor
Pin 7 (C1B): External oscillation capacitor
Pin 8 (VSS): Negative terminal of power supply
Pin 9 (VCO IN): Control terminal of voltage controlled oscillator
Pin 10 (DEMODULATOR OUT): Demodulation output terminal, used for FM demodulation
Pin 11 (R1): External oscillation resistor
Pin 12 (R2): External oscillation resistor
Pin 13 (PHASE COMP II OUT): The output terminal of phase comparator II
Pin 14 (SIGNAL IN): Signal input terminal
Pin 15 (ZENER): The negative electrode of the internal independent Zener voltage regulator tube
Pin 16 (VDD): The positive terminal of the power supply
• It provides a lock indicator pin that can help users judge whether the phase-locked loop has successfully locked the frequency of the input signal to avoid performance degradation caused by signal loss or frequency drift.
• It is capable of delivering an extended voltage range spanning from 3 V to 18 V while ensuring a consistent operational state, unaffected by fluctuations in voltage, be it high or low.
• The CD4046BE exhibits low dynamic power consumption. With a center frequency f0 set at 10kHz, it consumes only 600μW, rendering it a micro-power device ideally suited for extended usage and high-frequency applications.
• Its input impedance is up to about 100MΩ. This high impedance characteristic can reduce signal loss and improve signal fidelity, allowing it to maintain better performance during signal transmission.
• It is equipped with a tunable oscillator whose operating frequency can be sensitively adjusted through an external control voltage. After locking the input signal frequency, we can achieve precise control of its output signal by adjusting the VCO's output frequency.
CD4046BE is a phase-locked loop integrated circuit, and its principle is consistent with that of a phase-locked loop. It first compares the input signal with the reference signal, then filters it to obtain a stable DC voltage, and then uses the feedback loop to control the frequency of the voltage-controlled oscillator to achieve synchronization with the reference signal.
By continuously adjusting the frequency of the VCO, the phase difference between the input signal and the feedback signal is maintained at a stable value, thereby achieving closed-loop control of the phase-locked loop. This control mechanism enables the CD4046BE to track the frequency changes of the input signal and realize the frequency synthesis function.
1. Frequency Doppler measurement
CD4046BE can be used to measure Doppler frequency shift. In radar systems, this integrated circuit has the characteristics of high sensitivity and fast response, and can accurately detect the speed and direction of the target's movement.
2. Frequency synthesis
It adjusts the oscillator frequency and phase in real time by comparing the external reference signal with the internal oscillator signal to ensure the accuracy of the output clock signal.
3. Clock recovery
In digital communications, it can also be used to recover the clock signal from the received signal in order to correctly demodulate the digital data.
4. Oscillator control
It can be used as the frequency and phase control element of the oscillator to adjust the output frequency and phase of the oscillator.
First, we need to choose the appropriate modulation type and carrier signal type according to the specific application scenario. Common digital modulation types include binary phase shift keying (BPSK) and quadrature amplitude modulation (QAM).
Next, we establish a connection between the CD4046BE and the modulator and demodulator components, creating a fully functional communication link. It's crucial to ensure that the signal levels at the inputs and outputs of the modulator and demodulator align with the signal levels of the CD4046BE.
Once the circuit is connected, we proceed to configure its parameters to suit the particular application scenario and chosen modulation method. These parameters encompass factors like the frequency range of the VCO, the filter type and its associated parameters, and the frequency division ratio of the frequency divider, among others.
Subsequently, we input the digital signal into the modulator, which transforms it into an analog signal and superimposes it onto the carrier signal. The combined signal is introduced through the input pin of the CD4046BE, with the modulated signal emerging from the output pin of the CD4046BE.
To retrieve the original digital signal, the modulated signal is subjected to demodulation via a dedicated demodulator. The demodulated signal is then fed into the input pin of the CD4046BE, and the CD4046BE's output pin delivers the restored digital signal.
Following the completion of circuit connections and parameter adjustments, it becomes essential to conduct testing and debugging procedures to ensure the accuracy and reliability of the digital modulation and demodulation processes.
Frequently Asked Questions
1. What is CD4046?
CD4046 is a Micropower Phase-Locked Loop (PLL) with a phase detector that compares the phase of the output signal with the phase of the input signal and adjusts them to make matching signals from both ends.
2. How does CD4046 work?
The system consists of three parts: phase comparator, low-pass filter (LPF), and voltage-controlled oscillator (VCO). All parts are connected to form a closed-loop frequency-feedback system. With no signal input applied to the PLL system, the error voltage at the output of the phase comparator is zero.
3. What is the power supply voltage range for the CD4046BE?
The CD4046BE typically operates from a power supply voltage range of 3V to 18V, making it suitable for a wide range of electronic systems.
4. How does PLL works?
A phase-locked loop or phase lock loop (PLL) is a control system that generates an output signal whose phase is related to the phase of an input signal. There are several different types; the simplest is an electronic circuit consisting of a variable frequency oscillator and a phase detector in a feedback loop.
5. What is the function of the loop filter in the CD4046BE?
The loop filter filters and smoothes the error signal from the phase detector, providing a stable control voltage to the VCO. It helps in maintaining a locked phase relationship between the input and output signals.
