Re: Si570 LVDS Output Impedance

Clifford Heath

On 23 Apr 2019, at 11:12 am, Alfredo Mendiola Loyola via Groups.Io <> wrote:
I will use a 1:4 transformer with center tap to connect the output of the si570 (LVDS).
The secondary of the transformer (Center Tap) will be connected to the differential outputs of the si570
The primary of the transformer will be connected to a 3dB PI attenuator to get 50 ohm at the input and output of the attenuator.

The si570 datasheet states that the LVDS model has an output of 0.7 vpp {swing (diff)}

If I use a 1:4 transformer (Coilcraft PWB-4-BL) what will be the output peak to peak voltage at the transformer Primary?
1:4 impedance is 1:2 voltage ratio. 0.7Vp-p would reduce by 2:1 to 0.35Vp-p, which is 0.12Vrms.
Into 50 ohms that's about -5dBm.

Clifford Heath.

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