Emmanuel Pistono

High-Performance Shielded Coplanar Waveguides for the Design of CMOS 60-GHz Bandpass Filters

This paper presents optimized very high performance CMOS slow-wave shielded CPW transmission lines (S-CPW TLines). They are used to realize a 60-GHz bandpass filter, with T-junctions and open stubs. Owing to a strong slow-wave effect, the longitudinal length of the S-CPW is reduced by a factor up to 2.6 compared to a classical microstrip topology in the same technology. Moreover, the quality factor of the realized S-CPWs reaches 43 at 60 GHz, which is about two times higher than the microstrip one and corresponds to the state of the art concerning S-CPW TLines with moderate width. For a proof of concept of complex passive device realization, two millimeter-wave filters working at 60 GHz based on dual-behavior-resonator filters have been designed with these S-CPWs and measured up to 110 GHz. The measured insertion loss for the first-order (respectively, second-order) filter is -2.6 dB (respectively, -4.1 dB). The comparison with a classical microstrip topology and the state-of-the-art CMOS filter results highlights the very good performance of the realized filters in terms of unloaded quality factor. It also shows the potential of S-CPW TLines for the design of high-performance complex CMOS passive devices.

A Lossy Circuit Model Based on Physical Interpretation for Integrated Shielded Slow-Wave CMOS Coplanar Waveguide Structures

This paper presents a new physical model for shielded slow-wave coplanar waveguide structures. This lossy electrical model is based on physical behavior of the transmission lines. It allows a better understanding of the losses distribution along the structure. The ohmic losses in the coplanar strips, as well as the ohmic losses and the eddy current losses in the floating shield strips are studied for transmission lines having different geometrical dimensions and hence electrical characteristics. The model is then validated on different CMOS technologies and leads to the efficient optimization of the slow-wave transmission lines, especially concerning the floating shield dimensions.

Performance Improvement Versus CPW and Loss Distribution Analysis of Slow-Wave CPW in 65 nm HR-SOI CMOS Technology

High-performance integrated slow-wave coplanar waveguides (S-CPW) are compared with conventional coplanar waveguides (CPW) fabricated in a 65-nm High-Resistivity-SOI (HR-SOI) CMOS technology. As expected, S-CPW demonstrates better performance at millimeter-wave frequencies in term of higher effective dielectric permittivity, which is due to the patterned floating shield inserted between the transmission line and the substrate. In addition, S-CPW shows a lower attenuation constant despite of the added metallic patterned floating shield on HR substrate. For demonstration purpose, both low- and high- characteristic impedance S-CPW and CPW are characterized. For 28-Ω S-CPW and 65-Ω S-CPW, the effective dielectric permittivity is improved by a factor of 6 and 2, respectively. Meanwhile, attenuation constants of slow-wave structures are lower than 0.9 dB/mm and 0.57 dB/mm at 60 GHz, compared to CPW ones which are as high as 1.5 dB/mm and 0.95 dB/mm, respectively. Furthermore, the loss distribution for the S-CPW structure is detailed by varying the patterned floating shield length for both standard Bulk and HR-SOI substrates.

Characterization of Thin Dielectric Films up to Mm-Wave Frequencies Using Patterned Shielded Coplanar Waveguides

This letter presents an original method based on Patterned Shielded CoPlanar Waveguides transmission lines (patterned S-CPW TLines) for the wideband characterization of thin dielectric materials, up to millimeter-wave frequencies. The proposed method is easy to use and a very promising candidate to reach a better precision than classical methods. The dynamic for the relative permittivity (respectively the dielectric loss tangent) determination is 3.8 times (respectively, 1.9 times) higher compared to classical methods. The method is experimentally validated by the characterization of a thin SiO2 layer (1 μm).

A compact tune-all bandpass filter based on coupled slow-wave resonators

A compact hybrid tune-all bandpass filter based on coupled slow-wave resonators is demonstrated. The performance of such a filter electronically tuned with commercially available low-cost semiconductor varactors is promising in terms of center-frequency (f/sub c/) and bandwidth wide continuous tunings. Indeed, the -3 dB bandwidth of this filter can be tuned between /spl sim/50 MHz and /spl sim/78 MHz for a /spl plusmn/ 18%-center-frequency tuning around 0.7 GHz, an insertion loss smaller than 5 dB and a return loss higher than 13 dB at the center frequency. Moreover, for a /spl sim/50 MHz fixed bandwidth, the center frequency can be tuned between 0.51 GHz and 0.81 GHz leading to a relative /spl plusmn/ 24%-center-frequency tuning. Finally, the total physical length of the prototype filter is about 0.27/spl lambda//sub c/ for a 0.7 GHz center frequency.

A compact slow-wave substrate integrated waveguide cavity filter

This paper describes a miniaturized substrate integrated waveguide (SIW) filter by considering slow-wave substrate integrated waveguides. Compared to conventional SIW, the proposed topology includes internal blind metalized via-holes connected to the bottom metalized layer. These via-holes tend to confine the electric field in the upper part, while the magnetic field remains present in the whole substrate. Thus, a slow-wave effect is obtained by the physical separation of electric and magnetic fields. Using this novel topology, a 5th-order cavity filter centered at 11 GHz exhibiting a bandwidth of 900 MHz was designed, realized and measured. The filter surface area is more than three times smaller compared to classical SIW approaches. Measurements are in good agreement with simulations, validating the potential of the SW-SIW topology for RF and millimeter wave applications.

Synthesis method for the parallel-coupled stub-loaded resonator filters

This paper describes a synthesis method for parallel-coupled filters based on short-circuited stub-loaded resonators. Synthesis formulas were derived for homogeneous medium. Simulations are presented to validate the theory for three relative bandwidths 2, 4 and 8 %. For a proof-of-concept a third-order stripline bandpass filter was designed with a passband ripple of 0.01 dB and a relative bandwidth of 4.5%. Theory, simulations and measurements are in good agreement and thus validate the theory.

Half-Thru de-embedding method for millimeter-wave and sub-millimeter-wave integrated circuits

An accurate de-embedding method for millimeter-wave and sub-millimeter-wave integrated circuits is presented. In this “Half-Thru” de-embedding method, the pad-interconnects parasitics effects are modeled as a Half-Thru structure from both parts of the device under test. Several de-embedding methods over millimeter and sub-millimeter wave frequencies are compared in integrated technology by considering S-CPW transmission lines as device under test. From these comparisons we propose an effective way to de-embed transmission lines. The S-CPW transmission line model and results are obtained from full-wave electromagnetic simulations in BiCMOS 55-nm technology.

Miniaturized low-loss millimeter-wave rat-race balun in a CMOS 28 nm technology

This paper presents the design of an integrated rat-race coupler for balun applications based on high quality factor Slow-wave CoPlanar Waveguides (S-CPW) transmission lines in millimeter wave frequencies. The 28 nm CMOS advanced digital technology by STMicroelectronics is used. The design procedure is detailed. Phase-inverter and optimized criteria for the transmission lines characteristics are used to minimize insertion losses and surface on the die. A 3D full wave EM software coupled to a circuit simulator is used to optimize the various building blocs. The compact and low-loss rat-race coupler shows state-of-art very exciting and promising performances. It occupies a 0.086 mm2 area. From 52 GHz till 67 GHz, return loss is better than 15 dB, while coupling factors are identical, varying between −4.2 and −4.4 dB, that means 1.4 dB maximal insertion loss. Finally between 13 and 85.5 GHz, the phase difference is kept constant, equal to 180°±1° while the isolation is better than 44 dB.

Millimeter-wave CMOS power amplifier using slow-wave transmission lines

A three-stage 60-GHz power amplifier was implemented in a 65 nm CMOS technology. High-quality-factor slow-wave coplanar waveguides were used for input, output and inter-stage matching networks in order to improve the performance. In Class-A operation, the power amplifier exhibits a measured maximum linear power gain G of 18.3 dB at 55 GHz, with a 3-dB bandwidth of 8.5 GHz. The measured 1-dB output compression point OCP1dB and the maximum saturated output power Psat are 12 dBm and 14.2 dBm, respectively, with a DC power consumption of 156 mW under 1.2 V voltage supply. The measured peak power added efficiency PAE is 16 %. The die area is 0.52 mm2 (875 ×m × 600 μm) including all the pads, whereas the effective area is only 0.24 mm2.