Usually, the voltage of Vref is 1.7~1.9v in the AD8302's datasheet. But the Verf is about 0.4V in my device, and the schematic as follow.
where the problem is?
The AD8302 draws about 20 mA typical, so you have a HUGE voltage drop across R163.
Change it to 10 ohms.
I moved your questions about AD8302 in RF and Microwave community. jdobler should be able to assist you further on this.
I change the R163, it become normal. thank you!
I want to ask another question. The input signal of AD8302 need 223.61uV~632.46mV, but actually my signal is about 1.4V.
So I must attenuation the amplitude of input signal. I find a measure, Resistance attenuation network, as follow.
1. should I add a voltage follower after the Resistance attenuation network?
2. do you have good advice?
Those pi attenuation networks work be fine as they maintain the 50 Ohms looking back towards the DUT inputs and you decrease the signal by roughly 16 dB, which puts it in the range of the AD8302.
Thank you. you are right.
However, the PI attneuation networks has a shortcoming, it can't flexibly change when the input signal changed. So ,Do you have better ways?
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