At the heart of any Phase Locked Loop, we see the Phase Detector. Simply put, this electrical component is critical to achieve the functionality of the phase locked loop (i.e. to achieve phase coherence and/or synchronization between two signals).
Even though the Phase Locked Loop is a relatively simple electrical configuration, the design and implementation of the Phase Detector itself can be a little overwhelming. Today, we’ll be looking at what you need to consider when designing a phase detector for your circuit.
The 2 Main Types of Phase Detectors:
What further complicates phase detector designs is that the circuit diagram and the components used to achieve this functionality vary based on the type of phase detector used. So, if we can familiarize ourselves with the different types of phase detectors, we can make circuit design and implementation significantly easier.
Phase detectors can be divided into two main types, namely;
a) The Type I Phase Detector:
The Type I Phase detector is, generally, driven by a continuous signal that varies with time (i.e. analog). The problem with using a Type I Phase Detector is that its output waveform needs to be fine tuned and filtered to make it compatible with the other components of the Phase Locked Loop (chiefly the Voltage Controlled Oscillator VCO).
b) The Type II Phase Detector:
On the other hand, the Type II Phase Detector is only dependent on the phase shifts of the input and the reference waveforms. Based on the degree of the relative difference between these two phases, the Type II Phase Detector generates a voltage directly proportional to it.
This voltage is called the error voltage and can be reduced to 0 Volts by changing the phase of the frequency generated by Voltage Control Oscillator (VCO). When the output voltage of the Type II Phase Detector has been reduced to zero, the two signals (the input and the reference) are said to be coherent with each other.
Designing a Phase Detector:
The design and implementation of a phase detector is no easy feat. For starters, you must make sure that your circuit operates reliably over a large band of frequencies. Secondly, you must also take the relevant steps to minimize the impact of noise, interference, and attenuation to make your design practical.
Also, you must make your Phase Detector compatible with the Voltage Controlled Oscillator (VCO) and the Loop Filter used in the Phase Locked Loop. The utilization of components that aren’t compatible with each other will adversely affect the performance of your Phase Locked Loop.
Owing to the nature and the sheer volume of variables involved, we urge you to opt for a pre-made phase detector instead. We at ADSANTEC provide cost-effective electrical and electronic solutions that can operate over a large range of frequencies and can be used in high speed and high frequency applications.
Our online library includes the likes of Phase Detectors, Clock Dividers, Analog to Digital Converters, and PRBS generators, etc. Contact us today to ensure that your electrical network operates reliably.