Use MPY634 as phase detector

Yu-Chih Hsiao

Prodigy 60 points

Other Parts Discussed in Thread: MPY634

I want to use MPY634 as a phase detector.

The phase detector circuit is as below.

And I found MPY634 datasheet, the setup of MPY634 as phase detector is as below.

If I want to use MPY634 as picture1.

Then I connect input signal to MPY634 X1, and connect reference signal (the signal is square wave) to MPY634 Y1 ?

If I connect as my statement, the signal of MPY634 point B (picture 2) is the same as signal of point A (picture 1) ?

I want to know my statement is ture or not ?

If my statement is wrong, how can I use MPY634 (or other product) to setup a circuit as picture 1 ?

Thank you !

over 14 years ago

0 Thomas Kuehl over 14 years ago

TI__Guru* 93105 points

Hello Yu-Chih,

Yes, you would connect the MPY634 inputs as you described. The output at Fig. 6 point B should be similar to Fig. 1 point A; the output should be like a full-wave rectified waveform. However, there may be alternate analog circuits that would accomplish the full-wave rectification function and wouldn't require the square-wave multiplication.

Take a look at this TI aapplication bulletin about absolute value circuits. They produce a full-wave waveform from a sine input:

http://www.shvp.sc.ti.com/cgi-bin/pkg/Database_search/db_search.cgi?setup_file=thermal2.setup&session_file=32e7dc6531b6005b&exact_match=on&sort_by=2&pgroup=SLL&pkgtype=SOIC&gline=Low&submit_search=Submit+These+Search+Parameters

The rectified output could then be followed by the buffer and low-pass to extract the dc level.

Regards, Thomas

PA - Linear Applications Engineering