Development of finite ground coplanar (FGC) waveguide 90 degree crossover junctions with low coupling

A uniplanar GaAs MMIC subharmonic mixer has been designed and fabricated using an antiparallel diode pair in finite ground coplanar (FGC) waveguide technology. This mixer is designed to operate over an RF range of 58.5-60.5 GHz, an IF range of 1.5-2.5 GHz, and an LO frequency range of 14-14.5 GHz. Of several mixer configurations tested, the best results show a maximum conversion loss of 13.2 dB over the specified frequency range with a minimum LO power of 3 dBm. The minimum upper sideband conversion loss is 11.3 dB at an RF of 58.5 GHz and an IF of 2.5 GHz. This represents excellent performance for a 4X subharmonic mixer operating at 60 GHz.

Finite Ground Coplanar (FGC) waveguide transmission lines on CMOS grade silicon wafer (/spl rho/<0.01 ohm-cm) with a thick embedded silicon oxide layer have been developed using micromachining techniques. Lines with different lengths were designed, fabricated and measured. Measured attenuation and s-parameters are presented in the paper. Results show that the attenuation loss of the fabricated FGC lines is as low as 3.2 dB/cm at 40 GHz.

In this paper, we report on the development of W-band monolithic microwave integrated circuit (MMIC) power amplifiers using 0.1-/spl mu/m AlInAs/GaInAs/InP high electron mobility transistor (HEMT) technology and finite-ground coplanar waveguide (FGCPW) designs. In the device modeling, the Angelov nonlinear HEMT model was employed to predict the large signal performance of the device, and the results were validated by using state-of-the-art vector load-pull measurements. A two-stage single-ended W-band FGCPW MMIC using a 150-/spl mu/m-wide HEMT as the driver and a 250-/spl mu/m-wide HEMT for the output stage was designed, fabricated, and tested. The MMIC amplifier demonstrates a maximum output power of 18.6 dBm with 18.2% power-added efficiency and 10.6 dB associated gain at 94 GHz. This result is the best output power to date reported from an InP-based MMIC using FGCPW design at this frequency.

The performance of finite-ground coplanar (FGC) lines on GaAs and quartz for high-frequency monolithic-microwave integrated-circuit (MMIC) applications is experimentally investigated in this paper. The FGC lines on GaAs are covered with a thin layer of polyimide for passivation purposes. Permittivity and attenuation characteristics for these lines up to 118 GHz are presented and compared with the corresponding characteristics of FGC lines on a quartz substrate, which are commonly used for millimeter-wave applications. The impact of different characteristic impedance values in attenuation properties for both GaAs and quartz is also addressed. Results indicate that the loss on the lines does not depend on the substrate material, but rather on line geometry. All the lines tested show low-loss and low-dispersion characteristics.

The spurious passband caused by finite-ground coplanar waveguide (FGCPW) coupling structure is analyzed. Semicircular flaw ground structure can shift the spurious passband toward low frequency without affecting passband. Appling of this coupling structure, the FGCPW asymmetric half-wavelength coupling passband filter is designed. It has the center frequency 2.4 5 GHz, the insertion loss 0.3 dB and the bandwidth 0.1 GHz while there is a spurious passband at 1.9 GHz. After utilizing semicircular flaw ground structure, spurious passband is shifted downwards to 1.5 GHz without degrading passband performance. Moreover, this kind of filter can be used for high-frequency.

Innovative micromachined microwave switch with very low insertion loss

A grounded coplanar waveguide (GCPW) to rectangular waveguide (WR) transition is presented for operation in the E-band from 71 to 76 GHz, a worldwide allocated frequency slot for wireless communication. The GCPW-to-WR transition is designated for the E-band radio-over-fibre (RoF) wireless transmitter where it connects the 50 Ω coplanar waveguide (CPW) output of a high-frequency photodiode chip to a WR-12 waveguide. The presented transition is implemented on a ROGERS RT/Duroid 5880 RF laminate, it allows for quasi-hermetic packaging without the need of radomes and enables the use of a commercially available WR without the need for any mechanical modifications. Full-wave electromagnetic simulations show that the optimised transition presents a return loss of at least 30 dB and an insertion loss (IL) of only 2 dB. Experimental results confirm an average IL of only 2.5 dB. The key role of via-holes in reducing the IL is experimentally proven.

fA uniplanar transition from finite ground coplanar waveguide (FGCPW) to microstrip line operating at W-Band has been developed. The design is uniplanar and does not require viaholes or wirebonds. The transition, centered at 94 GHz, results in 0.2 dB insertion loss with a bandwidth of 20%. The return loss is better than -17 dB from 85 GHz to 100 GHz. To our knowledge, this simple transition shows state-of-the-art performance, and can be very useful for CPW-probe to microstrip circuit measurements.

New types of planar transmission lines employing multilayer structures are proposed for possible applications in microwave and millimeter-wave integrated circuits. Detailed investigations are presented through numerical results calculated using the spectral domain technique. The newly proposed transmission lines have many attractive features such as a large impedance range, flexibility and ability to realize complicated, densely packed integrated circuits, as well as miniaturization through the use of thin dielectric layers. Additionally, they possess all of the inherent advantages of the CPW and microstrip line. Their use in microwave circuits is exemplified through a low-pass filter realized using the new slot-coplanar lines with less than 0.5-dB insertion loss and better than 20-dB return loss. The filter's measured and calculated performances also agree well. >

Coplanar waveguide (CPW)/aperture coupled microstrip patch antennas constructed with ground coplanar waveguide (GCPW), finite coplanar waveguide (FCPW) and channelized coplanar waveguide (CCPW) are demonstrated. The measured characteristics show that the CCPW/aperture coupled microstrip patch antenna has the largest bandwidth, whereas the GCPW/aperture coupled microstrip patch antenna has the best front-to-back ratio.

A G-Band single pole single throw (SPST) switch for low insertion loss and high isolation is proposed and fabricated using 65-nm CMOS technology. A grounded co-planar wave guide (GCPW) folded coupled line topology is developed to improve the switch isolation and lower its insertion loss simultaneously. Based on this topology, this switch achieves minimum 2.4-dB insertion loss (IL) in G-Band with minimum 28.5-dB isolation (ISO). This switch consumes only 0.0067 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> chip area. To the authors' knowledge, this CMOS SPST switch achieves the best performance among the published switches in bulk CMOS processes at this frequency.

A fully micromachined millimeter-wave module for power combining is proposed and demonstrated. The proposed module consists of a monolithic-microwave integrated circuit (MMIC) RF sources, a finite ground coplanar (FGC) line-to-micromachined waveguide transition, and a section of micromachined waveguide, and thus can be fabricated cost-effectively using modern micromachining techniques. The module is tested with two types of GaAs monolithic frequency doublers as the RF source and shows excellent performance with an RF power efficiency of up to 25% at the output frequency of 72.2 GHz.

This paper describes our study on high-resolution measurements of the distribution of the radio frequency (RF) magnetic near field from a coplanar waveguide (CPW) with a size similar to power and ground lines in radio frequency integrated circuit chips using a magnetic force microscope tip and amplitude modulation of the line current. Cantilever resonance frequency modulation of approximately 25 kHz supplies the CPW with current and carrier frequencies up to 0.1 GHz. The CPW has a signal line width of 3 μm and a ground line width of 50 μm. The oscillation amplitudes of the tip with and without a DC magnetic field indicates that the distribution of the RF magnetic near field in the proximity of the CPW can be observed for a carrier frequency up to 0.1 GHz. This result also suggests that this method has potential as a new technique for high-resolution RF field measurements.

The coplanar waveguide (CPW) gap discontinuity is an important component of many applications in the monolithic microwave integrated circuits (MMICs). Therefore, accurate modeling of the CPW gap discontinuity is very important and fundamental for the design of MMICs. In this work, a new lumped equiva1ent-circuit model which can accurately describe the characterization of the CPW gap discontinuity from 0 to 150 GHz is proposed. The parameters are extracted from electromagnetic (EM) simulations simply and conveniently without any complicated optimization algorithms. And we make the model scalable in gap length, width and space. Satisfactory fitting accuracy is obtained between the model data and EM simulations, which verifies that our model can be implemented in computer-aided design software to reduce design time and save computer resources.

This paper proposes an inline insertion microwave microelectromechanical systems (MEMS) power sensor based on measuring the power dissipated by intrinsic ohmic losses of a coplanar waveguide (CPW) signal line by thermopiles. In order to achieve ultra reflection losses, cold junctions of the thermopiles are covered with the CPW ground lines for depressing electromagnetic coupling effects and serving as hot sink. To increase the sensitivity, the CPW ground lines are suspended above hot junctions of the thermopiles for reducing thermal losses and the CPW dimension near the thermopiles is designed to increase the temperature of the hot junctions. This sensor is completely compatible with the GaAs monolithic microwave integrated circuits (MMIC) technology. Experiments show that this optimized power sensor has resulted in reflection losses of less than -24.3 dB up to 26 GHz, with insertion losses of less than 0.37 dB. For the input power of 0.5-300 mW, the good linearity of the output response is obtained and average sensitivities are more than 6.26 and 8.21 mV/W at 2 and 20 GHz, respectively.