A phase-locked loop or phase lock loop (PLL) is a control system that tries to generate an output signal whose phase is related to the phase of the input "reference" signal. It is an electronic circuit consisting of a variable frequency oscillator and a phase detector. This circuit compares the phase of the input signal with the phase of the signal derived from its output oscillator and adjusts the frequency of its oscillator to keep the phases matched. The signal from the phase detector is used to control the oscillator in a feedback loop.
Phase-locked loops are widely used in radio, telecommunications, computers and other electronic applications. They may generate stable frequencies, recover a signal from a noisy communication channel, or distribute clock timing pulses in digital logic designs such as microprocessors. Since a single integrated circuit can provide a complete phase-locked-loop building block, the technique is widely used in modern electronic devices, with output frequencies from a fraction of a hertz up to many gigahertz.
There are several variations of PLLs. Some terms that are used are analog phase-locked loop (APLL) also referred to as a linear phase-locked loop (LPLL), digital phase-locked loop (DPLL), all digital phase-locked loop (ADPLL), and software phase-locked loop (SPLL).
Analog or Linear PLL (LPLL)
Phase detector is an analog multiplier. Loop filter is active or passive. Uses a Voltage-controlled oscillator (VCO).
Digital PLL (DPLL)
An analog PLL with a digital phase detector (such as XOR, edge-trigger JK, phase frequency detector). May have digital divider in the loop.
All digital PLL (ADPLL)
Phase detector, filter and oscillator are digital. Uses a numerically-controlled oscillator (NCO).
Software PLL (SPLL)
Functional blocks are implemented by software rather than specialized hardware.
5W PLL FM Transmitter (PIC16F627A)
The transmitter includes RDS/SCA input and Audio/MPX input with optional preemphasis. It can be used with or without stereo encoder. Tuning over the FM band is provided by two buttons that control dual-speed PLL. The transmitter can work also without the LCD display. Some experience with building devices of this kind are highly recommended. After complete parts placement: Check that there are no shorts bridging adjacent tracks or pads. Check electrolytic capacitors.....
Views: 2740 | Votes: 42 | Comments: 0 | Rating: 8 | Rank: 0 | Added: Jul 4, 2012 |
The IRPLLNR1 is a high efficiency, high
power factor, non-dimmable electronic ballast
designed for linear fluorescent lamp types.
The design contains an active power factor
correction circuit for universal voltage input
and a ballast control circuit using the IR2153
for controlling the lamp. Other features
include EMI filtering, transient protection and
lamp fault protection...
Views: 3734 | Votes: 70 | Comments: 0 | Rating: 6 | Rank: 0 | Added: Jun 30, 2012 |
FM Transmitter with PLL
In order to simplify the transmitter design, we've used the new pll circuit from Motorola :the MC145170. This PLL includes the prescaler and a serial standard bus called SPI. We advise to use the P2 version that fixes some init issues during the Power Up. This PLL circuit is definitely smaller than the old one, consequently we've added on the radio board, the power control circuit that allows to switch on, the RF signal when the lock detect is established. In fact a simple.....
Views: 4413 | Votes: 37 | Comments: 0 | Rating: 4 | Rank: 0 | Added: Jun 13, 2012 |
SAB6465 Frequency Divider
The circuit is a divider by 64 used in many RF applications like as satellite receiver, digital tuners, frequency counters, PLL, etc. The heart of circuit is an IC named SAB6456, but you can use SDA2101 or other equivalent chips. Each output is NOT of the other...
Views: 4823 | Votes: 98 | Comments: 0 | Rating: 3 | Rank: 0 | Added: Jun 11, 2012 |
Clock-recovery scheme suits low-SNR systems
A clock-recovery architecture can operate with NRZ digital signals, even at low SNRs. A clock-recovery subsystem is based on a PLL comprising a phase comparator, a loop filter, and a voltage-controlled oscillator (VCO)...
Views: 5698 | Votes: 35 | Comments: 0 | Rating: 2 | Rank: 0 | Added: Jun 2, 2012 |
5W Chinese PLL FM Transmitter With LCD Printed Circuit Board (PCB)
Here's PLL FM transmitter circuit from china. This circuit uses the familiar 2SC1971 for final power amplifier stage. The PLL controller of the FM transmitter use SAA1057 and PIC16F628 (download HEX file)...
Views: 3651 | Votes: 58 | Comments: 0 | Rating: 8 | Rank: 0 | Added: Jun 1, 2012 |
Frequency to Voltage Converters
This PLL can operate over a wide frequency range, not just
1 or 2 octaves but over 1 or 2 or 3 decades. It naturally
provides a voltage output which responds quickly to frequency
changes, yet does not have any inherent ripple.
Thus, it can be used as a frequency-to-voltage (F-to-V)
Views: 4402 | Votes: 67 | Comments: 0 | Rating: 9 | Rank: 0 | Added: May 8, 2012 |
Low-Cost PCO Billing Meter
In the circuit shown in Fig. 1, when the handset is off-hook, the optocoupler MCT2E (IC1) conducts and forward biases transistor T1, which, in turn, forward biases transistor T2 and energises relay RL1. In energised condition of relay, the upper set of relay contacts connects the positive supply rail to PLL (phase-locked loop) IC2 (LM567) pin 4, while the lower set of relay contacts couples the positive telephone lead to input pin 3 of LM567 via capacitor C1 and resistor.....
Views: 2893 | Votes: 58 | Comments: 0 | Rating: 4 | Rank: 0 | Added: Apr 22, 2012 |
Clock multiplier circumvents PLL
Using a standard PLL circuit, such as the CMOS 4046B with some passive components, is a well-known way to design a clock multiplier. Unfortunately, using a PLL in a digital circuit has two disadvantages: It takes a long time for the circuit to reach a stable output frequency, and the frequency-drift compensation has a complex design...
Views: 5196 | Votes: 74 | Comments: 0 | Rating: 4 | Rank: 0 | Added: Apr 5, 2012 |
VID2G project is an PAL/NTSC color generator & video identifier with digital sync regeneration, digital PLL, video Squelch output, predefined video pages, keyboard & full RS-232 access, etc. Dynamic and fixed ID`s, user positions, user selectable start page, Text script files for user created pictures (samples included in ZIP), and more...
Views: 375 | Votes: 15 | Comments: 0 | Rating: 3 | Rank: 0 | Added: Apr 5, 2012 |
CMOS PLL circuit
One of the most interesting projects to work with is that of a synthesizer that can accurately gnerate desired frequencies. This synthesizer uses just three CMOS chips and one PNP transistor. It is a fact that the transistor may be the hardest component to get in some parts of the world!! The synthesizer will generate a 3:1 frequency range anywhere from 300Hz to 4,000,000Hz (4MHz). Using the components shown you can feed the synthesizer with up to 12vDC but with only 9vDC.....
Views: 961 | Votes: 91 | Comments: 0 | Rating: 1 | Rank: 0 | Added: Apr 1, 2012 |
PLL block contains a phase detector, a charge pump, a loop filter, and voltage controlled oscillator circuit. VCO is the major part of PLL circuit and it affects the system performance in terms of ...
A simple PLL FM demodulator circuit using IC XR2212 is shown here. XR2212 is a highly stable, monolithic PLL (phase locked loop) IC specifically designed for communication and control system applic...
The circuit shown here is of a good Stereo FM transmitter that can transmit high quality signals up to a range of 70 feet. The circuit is based on BH1417 PLL stereo transmitter IC from Rhom semicon...
As a debut article, I'd like to share about one of the problems solved on a PLL circuit and problems when the product transferred to production calibration. Without revealing too many details due t...
Transmitter power amplifier, the output signal from BH1415F by 2 SC9018, 2SC3355, 2SC2053 amplified signal can reach more than 500 mW, adjusting well to achieve greater power. Measured by the pull ...
This really is my latest find, available at the Salvation Military Thrift Store in Dallas Texas. Bought for .00 cash. It had been labeled ( AS-Isn't Working). Used to do A litt... Posted by William...