Peak Detector

Ozancan Ugur

Other Parts Discussed in Thread: OPA657, TLV3601, TLV3603, THS4631, OPA356

Hi,

We want to build peak detector system that senses pulse peak with 50-200ns pulse width and 10kHz frequency for Lidar system. In our system, we are using STM32F411 as microcontroller. It cannot detect the pulse Vp-p level with its own ADC. Besides, we could not use high speed ADC either. Because, microcontroller has capability of max 100MHz clock. Due to the short pulse with and 10kHz frequency signal, we think that we need to use peak detector to sense Vp-p value of the pulse signal.

The signal level is changing between 0 to 4V so, the detector should sense with these levels For instance, the pulse signal level is 2.5V, the peak detector immediately set 2.5V. After this pulse, if next pulse signal is 1.5V, the peak detector should calibrate to the 1.5V instantly. The pulse detector should calibrate as regards next pulse signal. Since voltage level of the pulse signal depends on the distance. Thus, we can analyze the receiver signal without using high speed ADC.

Maybe there is no specific IC for peak detector but there can be solution to sense peak voltage level. I mean maybe there is no unique specific IC, but it can be integral circuits that solves this problem.

over 4 years ago

0 kai klaas69 over 4 years ago

Guru 140200 points

Hi Ozancan,

this thread might interest you:

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1009581/opa615-very-fast-pulse-peak-measurement

Do you drive the light pulse at the 10kHz rate by yourself? In this case you could reset the storage cap by software.

Kai

0 Ozancan Ugur over 4 years ago in reply to kai klaas69

Prodigy 170 points

Hi Kai,

We want to use peak detector for Lidar application. The frequency of laser pulse could be 5-15kHz, so we can say that the laser driver could be 10kHz. The frequency of the transmitter (laser driver) and receiver (APD/PIN diode) is determined by TDC. STM sends the command that start the pulse signal to the TDC with SPI communication, and then TDC produce the laser pulse.

However, even if the transmitter signal level does not change because of constant pulse, the receiver signal changes because of depending on distance or reflective surface shape and color. So, we need to get each signal pulse Vp-p value.

0 Chuck Sins over 4 years ago in reply to Ozancan Ugur

TI__Mastermind 25990 points

Ozancan

If I am understanding your request correctly, you are interested in the absolute value of the receive signal still and not just the presence of the pulse. If that is correct, I will need to move your post to our high speed amps forum for support. Your post has found its way onto the comparator forum where we can help determine the presence of a pulse that could trigger a TDC function to determine the delay/distance of the object but it appears you are seeking more information about the pulse received.

Chuck

0 kai klaas69 over 4 years ago in reply to Ozancan Ugur

Guru 140200 points

But you can properly reset the storage cap, right?

Kai

0 Ozancan Ugur over 4 years ago in reply to Chuck Sins

Prodigy 170 points

Hi Chuck,

We are already using OPA657 and comparator IC (LTC6752 fast comparator) to detect the receiver signal. But, we also need to get intensity of pulse signal. It is because when the signal coming from white or black surface, it also changes the voltage level of the receiver signal, which affects the rise time of the receiver signal, so the comparator can detect a little bit late like 3-5ns which depends on white or black surface. Therefore, lidar system can detect differently ToF (time of flight) because of variable rise time. We think to fix this issue to detect the voltage level to figure out what the ToF result is when we get different voltage level of receiver pulse signal.

0 Ozancan Ugur over 4 years ago in reply to kai klaas69

Prodigy 170 points

Hi kai,

Sorry I do not know how to reset the storage cap. Can you explain to reset the storage cap?

0 kai klaas69 over 4 years ago in reply to Ozancan Ugur

Guru 140200 points

Sorry, I thought that you had already read the links.

Kai

0 Chuck Sins over 4 years ago in reply to kai klaas69

TI__Mastermind 25990 points

Ozancan

Instead of the LTC6752, please consider our new high speed comparator which is even faster than the LTC device. We just started sampling this device and it has two variants (TLV3601 and TLV3603). The TLV3603 has an added feature for controlling hysteresis with an external pin.

Chuck

www.ti.com/.../tlv3601.pdf

0 Ozancan Ugur over 4 years ago in reply to Chuck Sins

Prodigy 170 points

Hi,

I checked the link about how to improve the accuracy of Peak Detector as high as possible, and I saw this design in the attachment. This solution is mostly give what we want. There are some overshoot when rising edge, but still it is ok. I just want to be sure that this opamp THS4631 is the suitable IC for the signal that 100ns pulse width, the Vp-p between 0 and 3V and 10kHz frequency?

yatao_ths4631_2 - Copy.TSC

0 kai klaas69 over 4 years ago in reply to Ozancan Ugur

Guru 140200 points

Hi Ozancan,

or using the OPA356?

ozancan_opa356.TSC

Kai

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Peak Detector