A Wideband Subharmonic Mixer Incorporating Signal Interference Technique Based Isolation Circuit

Sadhana Kumari,Priyanka Mondal

doi:10.35940/ijeat.b3072.129219

Abstract

A broadband (8.7 GHz – 11.5 GHz) performing passive sub-harmonic down-conversion mixer using signal interference technique (SIT) is demonstrated, designed and reported in this paper. The local oscillator (LO) frequency is half of the radio frequency (RF) for the 2xsub-harmonic mixer architecture; therefore, for the RF lying in the range 8.7 GHz to 11.5 GHz, required LO frequency range is 4.25 GHz to 5.65 GHz with 0.2 GHz fixed intermediate frequency (IF). With a broadband operation, designed prototype shows single sideband down-conversion loss in the range 9.6 dB – 12.6 dB. Moreover, large-signal testing infers an adequate linear trait of the proposed design, showing -3 dBm and 11.32 dBm for the 1 dB compression point and third order input intercept point, respectively.

Highlights

In the radio frequency (RF) front end mixers are the key component as it executes the frequency translation
Fundamental mixer suffers from the local oscillator (LO) leakage at the RF port
Theoretical investigation of anti-parallel diode pair carried out in [1] shows a complete suppression of even harmonic; this architecture can provide a better rejection of 2LO signal along with the suppression of the fundamental mixing products

Summary

INTRODUCTION

In the RF front end mixers are the key component as it executes the frequency translation. The advantages of the SHM over the fundamental mixer are manifold such as low LO leakage at the RF port, inherent noise suppression of LO [1], ease to design low frequency LO signal generator, just to name a few. It consists of RF/IF diplexer and LO network. The first thing to do before starting the design of the two networks is to calculate the diode embedding impedance pair (ZRF and ZLO for the RF and LO port, respectively). This task has been accomplished with the help of non-linear simulator of Advanced Design System (ADS).

Signal Interference Based Filter Design in Brief

FABRICATION AND MEASUREMENT

CONCLUSION