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A Balun-Integrated On-Chip Differential Pad for Full/Multi-Band mmWave/THz Measurements
A simple method using lumped inductors to compensate unequal even- and odd-mode phase velocities in parallel coupled microstrip lines is presented. The singly and doubly compensated cases are analyzed to enable the optimum inductor values and the electrical lengths of the compensated coupled lines to be calculated from closed-form expressions. The technique proposed not only improves the performance, but also yields a more compact design. To demonstrate the technique's broad range of applicability, the compensated coupled-line structure is used to enhance the performance of a 900-MHz Lange coupler, a 1-GHz multisection 10-dB coupler, a 900-MHz planar Marchand balun, and a 1.8-GHz parallel coupled bandpass filter
This paper presents an explicit analysis of the bandwidth and port imbalance of a subquarter-wavelength transmission-line (t-line) transformer and verifies this with the design of a two-stage D-band power amplifier (PA). Series power combining techniques incorporate both stacked heterojunction bipolar transistors (HBTs) and power combining using an 8-way sub-quarter-wavelength t-line transformer above 100 GHz. The extremely compact power combining methodology leads to a small die area of 0.62 mm
2
and a record 254-mW/mm
2
output power per unit die area. The PA has been fabricated in a 90-nm silicon germanium BiCMOS technology and produces more than 21-dBm output power over the frequency range of 114-130 GHz with a peak output power of 160 mW ≈ 22 dBm at 120 GHz and a 3-dB small-signal bandwidth of 35 GHz. This output power is 32% higher than the highest prior art, while the chip area is 77% smaller.
In this paper, a new comprehensive analytical derivation and discussion of the multimode thru-relfect-line (TRL) calibration based on the new generalized reverse cascade matrices is presented. The advantage of the presented formulation is that it can account for certain symmetries in the measurement setup and reflect them in the symmetry of the derived relationships. The focus is on the two-mode case since this covers the majority of the practical applications. To demonstrate the effectiveness of the new formulation, the practical use of the multimode TRL calibration technique for de-embedding purposes is discussed. The common de-embedding assumptions such as reciprocity and symmetry are analyzed and their consequences on the multimode TRL calibration are discussed. It is shown that these assumptions applied to the embedding networks can reduce the requirements on the reflect standard. The use of the multimode TRL calibration technique for un-terminating purposes is discussed. It is demonstrated that in the special de-embedding case it is possible to completely characterize the partially leaky embedding networks. The problems of interpretation and re-normalization of the measured scattering parameters are also discussed. Finally, the on-wafer measurement results are presented that verify the multimode TRL approach for four-port vector network analyzer calibration and de-embedding of differential devices.
This study presents an asymmetric broadside coupled balun with low-loss broadband characteristics for mixer designs. The correlation between balun impedance and a 3D multilayer CMOS structure are discussed and analyzed. Two asymmetric multilayer meander coupled lines are adopted to implement the baluns. Three balanced mixers that comprise three miniature asymmetric broadside coupled Marchand baluns are implemented to demonstrate the applicability to MOS technology. Both a single and dual balun occupy an area of only 0.06 mm2. The balun achieves a measured bandwidth of over 120%, an insertion loss of better than 4.1 dB (3 dB for an ideal balun) at the center frequency, an amplitude imbalance of less than 1 dB, and a phase imbalance of less than 5deg from 10 to 60 GHz. The first demonstrated circuit is a Ku-band mixer, which is implemented with a miniaturized balun to reduce the chip area by 80%. This 17-GHz mixer yields a conversion loss of better than 6.8 dB with a chip size of 0.24 mm2. The second circuit is a 15-60-GHz broadband single-balanced mixer, which achieves a conversion loss of better than 15 dB and occupies a chip area of 0.24 mm2. A three-conductor miniaturized dual balun is then developed for use in the third mixer. This star mixer incorporates two miniature dual baluns to achieve a conversion loss of better than 15 dB from 27 to 54 GHz, and occupies a chip area of 0.34 mm2.
Terminal characteristic parameters for a uniform coupled-line four-port for the general case of an asymmetric, inhomogeneous system are derived in this paper. The parameters (impedance, admittance, etc.) are derived in terms of two independent modes that propagate in two uniformly coupled propagating systems. The four-port parameters derived are of the same form as those obtained for the symmetric case resulting in similar port equivalent circuits for various circuit configurations considered by Zysman and Johnson. The results obtained should be quite useful in designing asymmetric coupled-line circuits in an inhomogeneous medium for various known applications.
A generalized network model for asymmetrical and inhomogeneous
coupled lines has been derived based on normal mode parameters. This
model is useful for synthesis of single and multilayer coupled-line
circuits, such as planar baluns and directional couplers. The synthesis
procedures are described and have been verified by comparing with
analysis results
The scattering matrix of asymmetric coupled two-line structures in
an inhomogeneous medium terminated in a set of impedances that are equal
to the characteristic impedances of the individual, uncoupled lines is
derived in terms of the coupled-mode parameters. It is shown that the
structures can compose an ideal backward-coupling directional coupler,
perfectly matched and isolated at all frequencies, if the inductive
k L and capacitive kC coupling
coefficients of the coupled lines are equal. The effect of the nonideal
equalization of the coupling coefficients on the coupler critical
parameters is investigated. The normal-mode parameters (mode numbers and
mode impedances) in the proximity of the point when
kL=kC and at that point are also examined.
Numerical results confirm the validity of the analysis and prove the
possibility of an asymmetrical coupler design with very high directivity
A Compact Broadband Marchand Balun for Millimeter-Wave and Sub-THz Applications
- M Hossein