Digital Vs. Analog Phase measurement I'm working on a Ultrasonic Transducers resonance tracking system. Where phase shift between Voltage and Current is the feedback signal for my system when phase difference is Zero that means system is resonant other wise depending on the phase difference frequency will be changed proportionally. I went through lots of different techniques of phase detection which includes Several

Analog(Comparatively Simple) techniques such as:- 


Phase Locked Loop 
Zero Crossing Based Phase Measurement 
Simple Phase Detector ICs


Digital(Complex DSP Based) Techniques Using Mathematical Algorithms such as:-


Cross Correlation 
FFT 
Goertzels Algorithm 
Sine Wave fit Methods 
VVV


So, My question is:- Which system will be best to use for a phase difference calculation analog or digital?

Considerations &amp; Preferences:- Transducer is noisy (Gaussian white noise + harmonics of fundamental). Accurate phase difference calculation is crucial.
Digital has one major challenge for control application: latency.

Any digital system needs to include A/D conversion, processing and D/A conversion. The minimum amount of latency is 1/SampleRate even if you don't do anything else but a straight wire. You also typically can't use off-the-shelf sigma-delta-converters since these have significant amount of conversion latency.

Most digital control systems tend to use heavy oversampling and fast one-shot converters to work around this problem. Once you have the basic infrastructure in place, the digital domain offers a large variety of algorithms that are highly configurable and effect. However the cost of entry is high.