Chopper Phase Detector - Circuit Analysis

Gregory explains the working principles and makes a circuit analysis of a Chopper Phase Detector, from an HP 334A Distortion Analyzer.
The phase detector uses a differential amplifier and a single chopper transistor, chopping the incoming error signal, generating a DC level proportional to the phase difference.
The differential amplifier generates two out-of-phase signals that follow to the transistor chopper phase detector.
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00:44 - Introduction
02:06 - Wien Bridge
04:22 - Phase error - in phase and quadrature
05:20 - Wien Bridge tuning
05:58 - Phase detector
07:20 - Differential amplifier
08:20 - Chopper phase detection
11:40 - How the circuit works
12:40 - Waveform diagrams
14:38 - LTspice simulation
Reference:
www.pascalchour.fr/ressources...

[@andrewphillip8432]

Really elegant! I built a chopper using analog switches once. Looking forward to trying this out, I think it would be a improvement

[@AllElectronicsChannel]

Go for it!

[@aduedc]

Nice circuit thanks for sharing.
This gives me an idea to design wide band phase detector.
We can measure current on a line amplify it to make a square wave, or use a zero crossing detector to generate square wave, do the same with voltage and use a PLL's PFD for phase detection, and then use a charge pump, and then a filter to integrate the output of the charge pump. The output voltage will be proportional to the phase difference, between current and voltage or power factor.
You can do the same thing with two voltages, as well.

[@AllElectronicsChannel]

Beautiful!

[@like_cabezon3810]

Wow very interesting. Looks like the microwave sampling phase detector that you have explained also when the two strobes Need to be differential to Not affect the Output. All of those old manuals are filled with knowledge and good ideas to use.

[@igorb4650]

Neat approach with virtual ground, even from cutting costs perspective

[@AllElectronicsChannel]

indeed!

[@saarike]

Really interesting!!! Thank you.

[@ralvarezb78]

Hi Greg, these feedback loop techniques fornulling reminds me analog Least Mean Squares and also feedfoward linearization (of course these are other different subjects, but Im talking about nulling feedback loop and main idea).
Another brilliant video, good job!

[@AllElectronicsChannel]

Interesting!!! Thanks
I never heard of the analog LMS concept 😳😳😳

[@heitortoledo6152]

Fala grande !!! Eu tenho um equipamento desse, é lindo de mais misericórdia!!! É de uma complexidade terrível hahahahah não achei muita coisa dele operando, usando ele manja. Abração grande !!!!!

[@evertontrindaderisso8855]

Olá tudo bem. vim procurar aquele video antigo que vc fala sobre impedância em falantes, que pra mim é o melhor video explicando sobre o assunto e ia mandar ele em um grupo mas notei que não tem mais ele. Vc teria ele para me mandar?

[@uchihaluoutsider8956]

Ei Gregory, Poderia disponibilizar novamente o vídeo em que você faz recomendações de livros? Recentemente consegui dinheiro para comprá-los, mas quando fui checar o vídeo da lista de livros que você passou, vi que ele não estava mais disponível.

[@AllElectronicsChannel]

Send me a mail

[@bumohamedubualooy7111]

what is the use of c3? in some other instruments the diff pair have similiar capacitors like c3 in series with small resistor, is it feedback?

[@AllElectronicsChannel]

C3 that couples the signal from one emitter to the other.

[@doctortono]

3:26 where I can find the theorical support for thar 1/3 of incomming signal?? DO you have bibliography or a theory notes for please?

[@AllElectronicsChannel]

Just search about the Wien Bridge oscillator. The 1/3 follows readily from the analysis of the RCs networks.

[@doctortono]

@@AllElectronicsChannel ok thanks!