A 2-20 GHz Analog Lag-Correlator for Radio Interferometry

TL;DR

This paper introduces a broadband analog lag correlator for radio interferometry operating between 2-20 GHz, demonstrating its design, testing, and suitability for future astronomical applications.

Contribution

The paper presents a novel broadband analog lag correlator design with integrated components and successful bench testing for radio interferometry.

Findings

Correlator response is stable across the entire frequency band.

System noise is not limited by the correlator performance.

Prototype successfully tested with promising results.

Abstract

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.