Where did my signal go? A discussion of signal loss between the ATE and UUT

Automatic Test Equipment (ATE) is now testing Units Under Test (UUTs) with signals that operate with data rates of several gigabits per second. Therefore, the test engineer must understand and account for the signal degradation through the transmission path. These high-speed digital signals typically pass through a variety of transmission media between the input/output (I/O) buffers on the ATE to the I/O buffers on the UUT. This paper highlights several considerations for the test engineer who is creating the test and system setup for a multi-gigabit per second bus. The paper discusses the contributors to DC and AC signal loss as well as methods to help minimize these losses. The paper focuses on multi-gigabit applications with matched double terminated transmission lines, but also touches on slightly slower busses with other termination schemes.