Design of 300 GHz Combined Doubler/Subharmonic Mixer Based on Schottky Diodes with Integrated MMIC Based Local Oscillator

Abstract

In this paper the design and experimental characterization of a combined doubler-subharmonic mixer based on Schottky diodes which uses a 75 GHz MMIC based local oscillator is presented. This solution integrates in the same substrate the doubler and the mixer, which share the same metallic packaging with the local oscillator. The prototype has been fabricated and measured. For characterization, the Y-Factor technique has been used and the prototype yields a best conversion loss and equivalent noise temperature of 11 dB and 1976 K, respectively, at 305 GHz. This performance is close to the state of the art, and shows the potential of this approach, which allows a significant reduction in terms of size and volume.

A Millimeter-Wave 4th-Harmonic Schottky Diode Mixer with Integrated Local Oscillator

“…This can be ascribed to losses in the circuits and to the output power being lower than the nominal level. This behavior is similar to that reported in [8], where a similar integrated LO was used. Unfortunately, with the current configuration the LO power cannot be measured to confirm this hypothesis.…”

“…Very compact configurations can be found in [6,7]; however, even though in [6] the modular approach allows the creation of a dense and uniform array of receivers, the local oscillator (LO) is external, built as an independent element, which reduces the integration level. An example of LO integration can be found in [8], where an MMIC-based LO around 75 GHz was used together with a Schottky diode multiplier and subharmonic mixer to obtain a receiver operation frequency around 300 GHz. This approach integrates the LO in the same metallic package where the submillimeter-wave components are built and consequently allows weight and size reduction.…”

“…In this paper, we simplify this approach and evaluate the performance of a 4thharmonic mixer pumped with a similar MMIC-based LO source. The use of this type of configuration, for which RF = 4 × f OL ± IF [9][10][11], allows extending the frequency range of submillimeter-wave mixers without requiring the use of a high LO frequency or a frequency multiplier for the LO signal, such as that proposed in [8,12]. In return, the conversion loss (CL) and equivalent noise temperature (ENT) will be higher; however, we have the advantage of simplified LO generation and a high integration level, which produces a more compact solution, since the multiplier and its bias circuitry are not necessary, and entails a simplification in terms of design.…”