Broadband microwave diode mixer design and implementation

Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Electrical and Electronics Engineering, Turkey

Approval Date: 2016

Student: EMRAH KOÇ

Supervisor: ŞİMŞEK DEMİR


Mixers play a critical role in design and development of wireless communication systems. Demanding requirements of the mixers are improvements in conversion efficiency, bandwidth, cost, and linearity. Schottky barrier diodes attract mixer designers due to their favorable characteristics leading to wide bandwidth, low-cost, and high efficient designs. This thesis demonstrates the design and implementation of two passive mixing circuits using Schottky barrier diodes at microwave frequencies. The first circuit is a broadband mixer which operates between 2 GHz and 18 GHz for RF/LO frequency with an average conversion loss of 7 dB. It provides LO-RF and RF-IF isolation of 30 dB over the most frequencies across the band. Furthermore, IIP3 of 13 dBm is achieved for LO drive level of 13 dBm. The second design proposes improved IF bandwidth up to 4 GHz. Conversion loss of 6 dB is typically measured for the RF frequency of 5 GHz-15 GHz. It shows excellent LO-RF isolation of better than 35 dB across the frequency band with similar IIP3 performance of first design.