MCU:SILICON LABS C8051FX20-TB 晶片:C8051F120
evaluation board:ANALOG DEVICES AD9954
AD9954 evaluation board:
only use DUT1
U13:PS10、SK、I/O SYNC、PD、CLKMODESEL are ground
RB_ENABLE don't connect anything
SCLK、SDIO、PS0、FUD、RESET、CS connect with Port4 of 8051
REF_CLK_DUT1 connect to signal generator(5MHz Square wave 500mVpp offset:250mV)
because no Oscillator on board.
Why the amplitude of output is changing with frequency?
The horizontal axis is frequency. log(1MHz)=6
The vertical axis is amplitude(V)
The sweeping frequency is from 100KHz to 10MHz.
The difference of amplitude is about 1.76V.
How can I solve this problem? Let the amplitude is fixed. Example: It is always fixed in 3V.