A novel via-less coplanar waveguide (CPW) to microstrip transition is discussed and design rules based on simulations and experimental results are presented. This transition demonstrates a maximum insertion loss of 1 dB over the frequency range from 10 GHz to 40 GHz with a value of 0.4 dB at 20 GHz. This transition could find a variety of applications due to its compatibility with RF systems-on-a chip, low loss performance, low cost and its ease of fabrication.

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Wideband coplanar waveguide RF probe pad to microstrip transitions without via holes

An improved broad-band microstrip-to-coplanar-waveguide (CPW) transition is developed on a basis of the frequency-dependence characteristic of an electromagnetic surface-to-surface coupling. A self-calibrated method of moments is extended to model this unbounded two-port discontinuity with the two dissimilar microstrip/CPW feeding lines. Numerical results are provided to demonstrate its frequency response of transmission under varied strip/slot dimensions and further exhibit its attractive ultra-broad-band transmission with low radiation loss. Next, the back-to-back transition circuits with the two different lengths are fabricated and measured to deembed in experiment the S-parameters of two single-transition structures. Predicted and measured results show good agreement with the return loss less than -10dB over the frequency of 3.2-11.2 GHz.

/pdf/broad-band-microstrip-to-cpw-transition-via-frequency-2xi7de91w2.pdf

Broad-band microstrip-to-CPW transition via frequency-dependent electromagnetic coupling

New designs of coplanar waveguide (CPW)-microstrip, CPW-stripline, conductor backed CPW (CBCPW)-microstrip, and CBCPW-stripline transitions are presented. Simulation using the high frequency structures simulator (HFSS) shows that the return loss of the CPW-microstrip transition is less than -25 dB up to 11 GHz. Similarly is the CPW-stripline transition. In the case of two back to back CBCPW-stripline transitions, the return loss is less than -22 dB up to 9 GHz. Experimentally, the S/sub 11/ of two back to back CBCPW-microstrip transitions on an alumina substrate is less than -15 dB up to 25 GHz.

Novel transition between different configurations of planar transmission lines

A novel wideband vertical transition for connecting the coplanar waveguide (CPW) to the microstrip line is proposed. This transition can be very useful for millimeter-wave packaging and vertical interconnects. It is multilayered, partly tapered, and consists of only one via interconnect. Two different transitions are designed. The first transition allows connectivity of a CPW with Zc=50 Ω to a microstrip line with Zc=16 Ω with a bandwidth of 10-60 GHz. The second transition has the same characteristic impedance, Zc=50 Ω, at the two ports. In this case, the operating frequency is from 40 MHz to 60 GHz. The return losses of both transitions are generally lower than -10 dB over their indicated frequency ranges, while the maximum measured insertion losses are 1.8 and 2.4 dB for the first and second transition, respectively. To extract the S-parameters of the transitions, a new thru-line technique, based on the standard thru-reflect-line two-tier calibration is introduced. Simulation and experimental results, showing good agreement, are presented and discussed.

Novel Wideband Transition Between Coplanar Waveguide and Microstrip Line

A transition from coplanar waveguide (CPW)-to-microstrip with vias is often used in wafer-probe measurements. This paper shows how field and impedance matching are used to develop a wideband transition. This paper demonstrates how the presence and placement of the vias affect the bandwidth and alters the impedance of the transition. The measured results on a transition show that a wideband transition with return loss better than 10 dB and an insertion loss less than 1.5 dB up to 36.64 GHz is obtained. The measurements show excellent agreement with simulation. The work presented in this paper provides a better understanding about a CPW-to-microstrip transition with vias as well as design procedures and principles that can be utilized to facilitate the realization of a broadband CPW-to-microstrip transition with vias.

Development of a Broadband Coplanar Waveguide-to-Microstrip Transition With Vias

A new design of a coplanar waveguide (CPW) to microstrip transition is presented. Simulation using the high frequency simulator software (HFSS) shows that a bandwidth of 13 GHz with less than -25 dB return loss can be achieved. The transition was fabricated and characterized. Experimentally, the S/sub 11/ of two back to back conductor backed CPW to microstrip transitions on InP substrate is better than -12 dB up to 14 GHz. For alumina substrate the S/sub 11/ was less than -15 dB up to 25 GHz.

W. Johnson

Papers

Novel design for coplanar waveguide to microstrip transition