Passive Circuit Technologies for mm-Wave Wireless Systems on Silicon

Abstract

The performance characteristics of transmission lines, silicon integrated waveguides, tunable LC resonators and passive combiners/splitters and baluns are described in this paper. It is shown that Q-factor for an on-chip LC tank peaks between 20 and 40 GHz in a 65 nm RF-CMOS technology; well below the bands proposed for many mm-wave applications. Simulations also predict that the Q-factor of differential CPW transmission lines on-chip can exceed 20 at 60 GHz in RF-CMOS when a floating shield is applied, outperforming unshielded variants employing more advanced metal stacks. A PA circuit demonstrator for advanced on-chip passive power combiners, splitters and baluns realizes peak-PAE of 18% and better than 20 dBm into a load at 62 GHz. An outlook to the enablement of digitally intensive mm-wave ICs and low-loss passive interconnections (0.15 dB/mm measured loss at 100 GHz) concludes the paper.Index Terms-Coplanar waveguide, integrated waveguide, mm-wave, monolithic inductors and capacitors, power amplifier, RF-CMOS, SiGe-BiCMOS.

A review of key development areas in low-cost packaging and integration of future E-band mm-wave transceivers

“…Another significant drawback to complete on-chip system integration is the high losses and low self-resonant frequencies of the passive circuitry surrounding the active transistors on the semiconductor die [26] at mmwave frequencies, an effect exacerbated by nearfield interaction between the on-chip passive and the host substrate after mounting [27]. Typical unloaded quality factors (Qfactors) for on-chip resonators at E-band frequencies have been demonstrated only up to 83 [28] for compound transmission line resonators, 43 for shielded transmission line resonators [29], 25 for single transmission line resonators [30] and below 15 for LC tank resonators [31]. This compares poorly with achievable unloaded Q-factors at mm-wave frequencies of over 200 in SIW [32], over 3,000 for ceramic dielectric resonators [30] and Q-factors in excess of 75,000 for machined waveguide resonators [33].…”

“…These devices all rely on extensive transmission line on-chip matching, dividing / combining and other passive networks [56] which may both attenuate significantly (due to the previously noted low Qfactors for passives) and cause unwanted radiation [57]. This loss translates into the degradation of noise figure in E-band low noise amplifiers (LNAs) [58], increase in phase noise of oscillators [59] and reduced efficiency of power amplifiers [31]. In the microwave domain, discrete transistors (commonly GaAs pHEMTs and GaN HEMTs [60]) are readily available off-the-shelf and are often used for custom circuit designs with off-chip passives.…”

Development of an Equivalent Circuit Model of a Finite Ground Coplanar Waveguide Interconnect in Mis System for Ultra-Broadband Monolithic Ics

“…where k and k were defined by Equations (5) and (6). The conductance per unit length of the FGCPW is related to its substrate partial capacitance as…”

“…Considerable research efforts have been expended to develop methods to rapidly and accurately model and characterize various on-chip interconnects [1][2][3][4][5][6]. For a data rate of 28 Gbps or higher, the interconnect impact becomes even more appreciable and needs to be modeled appropriately.…”

A comparison of basic 94 GHz planar transmission line resonators in commercial BiCMOS back-end-of-line processes

“…This is especially problematic in the implementation of on-chip filters, since the mid-band filter insertion loss is inversely proportional to the achievable resonator Q-factor [8]. Typical achieved unloaded quality factors (Q-factors) for on-chip resonators at V-and W-band frequencies have been demonstrated only up to 83 [9] for compound transmission line resonators, 43 for shielded transmission line resonators [10], 25 for single transmission line resonators [11] and below 15 for LC tanks [11]. …”