Design of a 0.5–18 GHz Wideband Frequency Down-Converter Module with a Local Circuit for an Electronic Support Measurement System

Abstract

In this paper, we describe the design and fabrication of a wideband frequency down converter module that has a local circuit with high gain, low spurious, high IP3 (3rd intercept point) characteristics, and reliability; this is accomplished by applying a chip-and-wire process using a bare type monolithic microwave integrated circuit (MMIC) device. To compensate for the mismatch among many sub-modules, an input module, filter bank module, output module, and local oscillator (LO) module suitable for sub-band frequency characteristics were designed and applied to the down converter. Th e frequency down converter module had three paths: 0.5−2 GHz (direct), 2−6 GHz (direct), and 6−18 GHz (converter). Amplitude-matched radio frequency (RF) semi-rigid cables of different lengths were used to connect to the internal sub-modules of the frequency down converter. The main RF line was a dielectric substrate, RT/duroid 5880, with a relative dielectric constant of 2.2 and a dielectric thickness of 0.127 mm. In the wideband frequency down converter module, the gain was 22.7 dB at low band (input frequency, 0.5−2 GHz) with a flatness of about 3.4 dB. Th e gain was 22.6 dB at mid band (input frequency, 2−6 GHz) having flatness about 2.0 dB. The gain was from 30 dB at edge frequency of high band (input frequency, 14−18 GHz) with a flatness of about 4.2 dB. The measured value of IP3 at LB was +23.52 dBm, +25.66 dBm and +23.44 dBm as the maximum value. The measured value of spurious (LO-2IF) at the converter path was 34.97 dBc as the maximum value.