Agilent offers the K-Series block downconverters, which extend the upper frequency limit of the N8975A from 26.5 GHz up to 110 GHz. The downconverter uses an internal LO to down convert the input signal to an IF that is within the measurement range of the NFA. The K-Series is offered in 13.5 GHz bands. For example, a customer that would like to make noise figure measurements to 52 GHz would order K40, K50, and K63 in order to bridge from the 26.5 GHz end frequency of the N8975A to the 52 GHz required.