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bouyang
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I am wondering if anyone has used AD8333 to demodulate a square wave input (Not the LO, but the RF input).
bouyang said:I am wondering if anyone has used AD8333 to demodulate a square wave input (Not the LO, but the RF input).
thankz said:how do you demodulate a square wave?
bouyang said:I have a CW square wave, I am hoping to extract its phase and amplitude related to a reference signal (supplied tot he LO port).
jim hardy said:Square waves?
I've AND'ed them after shifting to logic level voltage.
Resulting duty cycle is in proportion to phase and lends itself to averaging.
But no, i never used that device.
Baluncore said:I would feed the small noisy received square wave, (RX), through a wideband limiting amplifier first. Then I would phase lock an oscillator to that limited signal. The PLL could have a long time constant since only phase shift is required. A Voltage Controlled Crystal Oscillator, (VCXO), might be used. Measuring the phase difference between the TX and PLL(RX) would be significantly more reliable than processing noisy signals.
Design will depend on the bandwidth of the RX signal. Are you designing a laser range-finder ?
Thank you very much for the help!Baluncore said:I would first consider something like the AD8306.
See this link for; AN-691 "Operation of RF Detector Products at Low Frequency"
http://www.analog.com/media/en/technical-documentation/application-notes/AN-691.pdf
It lists;
AD8302 Special Purpose
AD8306 Demodulating Logarithmic Amplifier
AD8307 Demodulating Logarithmic Amplifier
AD8309 Demodulating Logarithmic Amplifier
AD8310 Demodulating Logarithmic Amplifier
AD8361 RF rms-to-dc Converter
AD8362 Exponential Logarithmic Amplifier
Some limiting amplifier ICs only generate the logarithmic RSSI signal, but you need output(s) from the limiting amp.
The latest WB limiting amps are used for xGHz optic fibre receive data amplifiers.
Many FM receiver chips have a limiting amplifier with RSSI and signal output(s). For example; the nxp SA604
http://www.nxp.com/documents/data_sheet/SA604A.pdf
The AD8333 is an integrated circuit (IC) designed for demodulating a square wave in various applications. It works by receiving a square wave input and converting it into a demodulated output signal through a low-pass filter and amplifier.
While the AD8333 is specifically designed for demodulating square waves, it can also be used for other waveforms with similar characteristics, such as pulse waves and rectangular waves.
The accuracy of the demodulated output signal depends on various factors such as the input signal quality, external components used, and environmental conditions. However, the AD8333 has a typical accuracy of +/- 0.5%.
The AD8333 has a maximum operating frequency of 10 MHz, which means it can accurately demodulate square waves with frequencies up to 10 MHz.
Yes, for optimal performance, it is recommended to use a low-pass filter and amplifier in conjunction with the AD8333. The datasheet of the AD8333 provides a recommended circuit for demodulating square waves with optimal performance.