The Zurich Instruments GHFLI Lock-in Amplifier extends the advantages of lock-in amplifiers – noise rejection, phase sensitivity, frequency tracking and more – to applications that operate at frequencies up to 1.8 GHz. The GHFLI contains two physical channels that operate as independent lock-in amplifiers. Each one is equipped with 4 dual-phase demodulators that enable parallel multi-harmonics and multi-frequency analysis, and with a 6 GSa/s signal generator for drive and reference signals. The demodulator filters can be tuned to give the best tradeoff between noise rejection and measurement speed. The USB and gigabit ethernet digital interfaces enable continuous data transfer to the computer at up to 4 MSa/s while the 4 high-speed and 4 high-precision auxiliary outputs can convert the measurement results, with custom scaling and offset, into analog signals for integration with other instruments.