Hello once again.
I'm getting large overshoots at the output of the LNAOUT. What I am trying to do is send an ultrasonic wave from one sensor and receive from another ultrasonic sensor. The sensors are approximately 20cm apart. I leave the LNAOUT open and probe it with my scope( I also loaded LNAOUT with 10k, but the results are still the same). Here are the registers that I modified. Just a quick refrence I use LNA in capacitive mode(circuit attached), external refrence at the pin VCOM and 40kHz transmit signal.
CONFIG_0 : 0xC5
CONFIG_2 : 0x81 //mode 1, external reference.
CONFIG_4: 0x5F //Multiple echo,
CONFIG_3 : 0x43
CLOCK_RATE : 0x02 // auto zero period (I tries all of the options and nothing changed.)
Here is the input circuit. The VCOM pin is biased with external opamp (specifically I use TL071 to bias and it's working fine). I am using TX1 and RX2.
Here is What I see on the oscilloscope at LNAOUT. First I see a very large overshoot and little sinusoidal which is not the received signal centered around VCOM. Blue trace is LNAOUT and the yellow trace is the START pin. The output rises after a while as expected because TDC1000 configured in standart mode.
