Wide-Band Single-Side Band Subharmonic Mixer Constructed With Re-Entrant Couplers and Lumped-Element Coupler

• Published in: IEEE microwave and wireless components letters 2008-12, Vol.18 (12), p.806-808
• Main Authors: CHIANG, Yi-Chyun, MA, Ming-Chuan
• Format: Article
• Language: English
• Subjects: Amplitude modulation; Applied sciences; Bandwidth; Circuit properties; Circuits; Couplers; Electric, optical and optoelectronic circuits; Electronic circuits; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Exact sciences and technology; Filtering; Frequency filters; Intermediate frequencies; Low pass filters; Microstrip; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Mixers; Noise levels; Prototypes; Quadrature coupler; Quadratures; Radio frequencies; Radio frequency; Signal convertors; single-side band (SSB) mixer; subharmonically pumped (SHP) mixer; Wideband
• ISSN: 1531-1309; 2771-957X; 1558-1764; 2771-9588
• DOI: 10.1109/LMWC.2008.2007708

This work presents a new configuration of single-side band (SSB) harmonically pumped mixer implemented by using two kinds of wide-band quadrature couplers to achieve the characteristics of wide operation bandwidth, high side band suppression and compact circuit size. A new type of 3 dB re-entrant microstrip coupler, which is easy to integrate with the surface-mounted devices, is adopted to achieve the required quadrature phase shifts of the radio frequency (RF) and local oscillation signals. The lump-element type of intermediate frequency coupler is not only able to have broadband characteristics and compact circuit size, but also provide the low-pass filtering function to eliminate the low-pass filter of the mixer in the conventional design. An experimental prototype of the proposed SSB mixer was manufactured. The measured conversion losses of the prototype, which includes the losses caused by couplers, are lower than 13 dB. It also shows greater than 20 dB side-band suppression over the RF frequency range of 2.2 to 2.85 GHz and the measured side-band suppression at some RF frequencies are up to 45 dB. The size of the S-band prototype fabricated on FR4 PCB is only about 40 x 45 mm 2 .