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| FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator |
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| maxwell3e10:
It's a good idea to test an up-ramp. For 8192 horizontal points one gets 8192 vertical points. So the vertical resolution should be 13 bits in this case. Here is the picture for an up ramp on FY6600. The scope resolution here is 5 mV/100 nsec per division. The steps are indeed about 2.4 mV=20V/8192. So the DAC is not at fault. It is the number of points in the waveform that is creating the steps. This is not purely FeelTech limitation. Rigol and Keysight are also limited to some (although lesser) extend by the waveform length. https://www.eevblog.com/forum/testgear/new-rigol-16-bit-function-generators-dg800900-series/msg2452248/#msg2452248 |
| radiolistener:
--- Quote from: maxwell3e10 on August 22, 2019, 08:34:37 am ---The steps are indeed about 2.4 mV=20V/8192. So the DAC is not at fault. --- End quote --- 10 V / 2.4 mV = 4166, it's very close to 4096. So, it seems like 12 bits. With 12 bit you will have 2.441 mV step. Do you measure it with 50 Ohm terminator on the oscilloscope connector? That's very important. |
| pantelei4:
--- Quote from: maxwell3e10 on August 22, 2019, 08:34:37 am ---It's a good idea to test an up-ramp. For 8192 horizontal points one gets 8192 vertical points. So the vertical resolution should be 13 bits in this case. --- End quote --- Yes, I was mistaken when I switched the waveform to ramp, the amplitude became 10V instead of 20V. Thus, it is not 14, but 13 bits, which are limited by the amount of memory. |
| maxwell3e10:
No, there is no 50 Ohm terminator and it is not needed. It would simply attenuate both the signal and the steps by a factor of 2. The scope is calibrated for Hi Z load, so 20V pp is indeed 20 Vpp without terminator. |
| radiolistener:
--- Quote from: maxwell3e10 on August 22, 2019, 08:59:45 am ---No, there is no 50 Ohm terminator and it is not needed. It would simply attenuate both the signal and the steps by a factor of 2. The scope is calibrated for Hi Z load, so 20V pp is indeed 20 Vpp without terminator. --- End quote --- such measurement is incorrect. With Hi-Z your oscilloscope will show you random amplitude, you cannot believe it. 100 ns step uses about 10 MHz bandwidth, at >10 MHz you can get very high amplitude mistake on 1 meter cable with HiZ input. |
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