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TX BB LPF and TX Secondary LPF

Question asked by Super on Jan 7, 2014
Latest reply on Jan 9, 2014 by tlili

HI,  i am working on a project based on AD9361


I use AD9361 Filter Guide.pdf to study filters' properties

According to the datasheet, there are 2 analog filters --BB LPF and 2nd LPF-- after DAC in TX path.

The BB LPF is a third-order Butterworth low-pass filter while the 2nd LPF is a single-pole low-pass filter

BUT what i concern is what the exactly schematic circuit diagram of these filters should be ?


Also based on the Filter Guide.pdf , thses filters' setting are programmed in registers 0x0C0 through 0x0CC  and  in registers 0x0D0 through 0x0D3 ,respectively. When i turn to AD9361 Register Map.pdf , go through registers 0x0C0 to 0x0CC(TX BASEBAND FILTER REGISTERS) and 0x0D0 to 0x0D3(TX SECONDARY FILTER REGISTERS), it refers to the calculation of R1, RP, Cx, CP of TX BB LPF and resistor, capacitor of TX 2nd LPF.

BUT what are the R and C or where should they be ?


sum up, I want to konw the  schematic circuit diagram of BB LPF and 2nd LPF.

plz help me.