Low Loss Non-Reciprocal Filter for Miniaturized RF-Front-End Platforms

MMIC GaAs Isolators and Quasi-Circulators With Co-Designed RF Filtering Functionality

“…Furthermore, when passive BPFs are realized with IC-based resonators, they exhibit high levels of IL (IL ∼ 4.5-9.3 dB in [14], [15]). To reduce the size of the non-reciprocal devices and BPFs, two major miniaturization approaches have been investigated: i) the integration of the non-reciprocal components into a chip using MMIC, CMOS, SiGe, technologies [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29] and ii) the RF co-design of the non-reciprocal components with the BPFs with or without ferrite-based elements [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44].…”

“…In yet another magnetless circuit-based design approach, spatiotemporally modulated (STM) switched capacitor arrays, transmission lines or resonator-arrays are employed within a three-port network to achieve non-reciprocity [46], [47], [48], [49]. Alternative integration schemes using PCB ( [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [48]) and CMOS based integration platforms ( [46], [47], [48], [49]) have been demonstrated. However, the operating principles of many of them have been demonstrated at frequencies <1.2 GHz (e.g., [32], [33], [34], [35], [36], [37], [40], [41], [48], [49]).…”

“…Alternative integration schemes using PCB ( [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [48]) and CMOS based integration platforms ( [46], [47], [48], [49]) have been demonstrated. However, the operating principles of many of them have been demonstrated at frequencies <1.2 GHz (e.g., [32], [33], [34], [35], [36], [37], [40], [41], [48], [49]). High-frequency implementations of STM-based circulators using CMOS technologies have also been shown to higher frequencies as for example at 6 GHz in [50], at 28 GHz in [51] and at 60 GHz in [52].…”

“…The second miniaturization technique is based on the combination of the function of the isolator/circulator with the function of the BPF into a single device [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44]. Using this method, either the BPF or the isolator/circulator can be removed from the RF front-end.…”

“…Using this method, either the BPF or the isolator/circulator can be removed from the RF front-end. Notable demonstrations include: i) the combination of a BPF and a ferrite-based circulator (BPFC) in [31], ii) STM-based non-reciprocal BPFs (NBPFs) in [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], iii) transistor-based NBPFs in [42], [43] and iv) transistor-based co-designed BPFs and quasi-circulators in [44]. While the ferrite-based BPFC in [31] was further miniaturized by capacitively loading its ferrite disk and by reconfiguring its transfer function, it exhibits moderate IL (2.7-4.5 dB) and cannot be integrated in an IC platform due to the presence of the external magnetic biasing.…”