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

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. The 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.