I'm interested in driving a 100-ohm differential load (i.e., two 50 ohm lines, 180 degrees out of phase) at up to 6 GHz. It looks like the ADL5565 might be a good candidate, but the data sheet seems to assume that it will be used at much lower frequencies as an ADC driver, working into a 200 ohm load. Can anyone address the pros and cons of running the ADL5565 as a 100-ohm differential line driver? What impact will the lower output Z have on parameters such as output swing?

Hi John,

You are right that the expected AC Performance (the Specifications section and the Typical Performance Characteristics section) assumed a load impedance of 200Ω but it doesn't mean that you can't use the device to other value of load impedance. Page 18 of the datasheet shows that your Source and Load impedance affects the differential gain of ADL5565. It is because your expected output signal will experience voltage divider formed by the output impedance(10Ω) and the load impedance(100Ω) which decrease the signal gain. Let me give you an example, supposed you have 1Vpp input voltage and Gain = 2. With Rload = 100Ω; Vout = 1.81Vpp and for Rload = 200Ω; Vout = 1.90Vpp. You can derive this from the formula at page 18 of the datasheet.

I hope it helps!

Thanks,

Emman