Phase-detector


Posted on Feb 8, 2013

The output of the detector contains a term related to the cosine of the phase angle. Two signals of equal frequency are applied to the inputs. The frequencies are multiplied together, producing the sum and difference frequencies. Equal frequencies cause the difference component to become de, while the undesired sum component is filtered out. The de component is related to the phase angle by the graph of Fig. 70-2B. At 90°, the cosine becomes zero, while being at maximum positive or maximum negative at 0° and 180°, respectively.


Phase-detector
Click here to download the full size of the above Circuit.

The advantage of using the balanced modulator over other types of phase comparators is the excellent conversion linearity. This configuration also provides a conversion gain, rather than a loss for greater resolution. Used in conjunction with a phase-locked loop, for instance, the balanced modulator provides a very low-distortion FM demodulator. Correct phase sequences (ABC, BCA, or CAB) produce trains of output pulses and illuminate the LED. The output stays low and the LED remains dark for incorrect sequences (BAC, ACB, or CBA) or for phase loss (phase A, B, or C missing).




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

200mW FM transmitter
Linear-ic-siren
Discrete Voltage Regulator
Lights Control for Model Cars
am rf amp for internal antenna circuit
Crystal Set 1
Magnetic pickup pre-amplifier circuit
ML7005 DTMF Transceiver ML7005DTMF Transceiver
5 volts high current power supply using 7805 voltage regulator
Medical ultrasonic atomizer 2
UC3625 brushless DC motor open loop speed control



Top