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SN75LVCP601: Application question and Network Analyzer Results

Part Number: SN75LVCP601

Reference Case Number: CS0219386


We designed a PCB to host the SN75LVCP601 SATA redriver chip and it works great, but I have some questions. First question is, what advice is there on using two of the redrivers on a single path, such as one redriver PCB placed at the host and the other redriver PCB placed at the device? The length between our host and device is approximately 4.5 ft. I have found switch setting for both sides that work and that is good, but we also have a scenario in which one of the redrivers might not be present and in that scenario the switch setting that worked with two does not work with one. Any advice/recommendations are appreciated.

Second question is, when I connect the redriver PCB to a four port network analyzer to measure the insertion loss, the transmit path shows an insertion loss across the entire frequency range (my max was set at 6 GHz), but the receive path insertion loss drops off to approx. -50 dB around 3.6 GHz. The drop off point can be extended if I increase the network analyzer stimulus power, but why would it do that?

Here are the test setups:

Transmit IL:

Port 1, Port 2 -> Into the host side of the redriver.

Port 3, Port 4 -> Out of the device side of the redriver.

Receive IL:

Port 1, Port 2 -> Into the device side of the redriver.

Port 3, Port 4 -> Out of the host side of the redriver.



  • Hi Jessica,

    We try to avoid multiple redrivers in a path since the signal integrity or eye opening tuning can be more difficult.  This is especially true for serial standards at 8 Gbps and above which are more likely to include link equalization training.

    If one of the redrivers may not be present, I would recommend to increase the receive and transmit equalization in that direction.  Hopefully these higher settings can work with or without the 2nd redriver.

    The receiver has an internal signal detection circuit.  Once the signal is above the normal operating range for this device the sensitivity drops.  When the this circuit does not detect the signal (like you are describing above 3.6 GHz) the outputs will mute.  When the outputs mute the VNA measurement will drop off to a very low number.  So I would say what you see with the VNA is entirely normal behavior for this device.