  We present the design and testing of a 2-20 GHz continuum band analog lag
correlator with 16 frequency channels for astronomical interferometry. The
correlator has been designed for future use with a prototype single-baseline
interferometer operating at 185-275 GHz. The design uses a broadband Wilkinson
divider tree with integral thin-film resistors implemented on an alumina
substrate, and custom-made broadband InGaP/GaAs Gilbert Cell multipliers. The
prototype correlator has been fully bench-tested, together with the necessary
readout electronics for acquisition of the output signals. The results of these
measurements show that the response of the correlator is well behaved over the
band. An investigation of the noise behaviour also shows that the
signal-to-noise of the system is not limited by the correlator performance.
