Microwave I-Q vector modulator using a simple technique for compensation of FET parasitics

An improved technique for the design of an unbalanced analog reflection-type on-chip vector modulator is presented. At microwave frequencies, voltage-controlled high-electron-mobility transistor (HEMT) like pseudomorphic HEMT (pHEMT) is often chosen as the variable termination in vector modulator. However, the parasitic elements of the transistor introduce amplitude and phase errors, which will degrade the overall performance of the vector modulator. Based on the establishment of pHEMT scalable parasitic model and characterization of bond-wire interconnection, we propose a method and a corresponding design procedure that mitigate the parasitic effects of pHEMT and achieve optimum performance of the vector modulator. The influences of Lange coupler characteristic impedance and compensation inductance on the vector modulator are analyzed first. Then, a method to determine the optimal values of characteristic impedance and compensation inductance is given, which relieves parasitic effects and obtains symmetric constellation. In our proposed design, the compensation inductance is realized through bond-wire inductance, eliminating the requirement of the on-chip inductor. To validate the design concept, a vector modulator module, composed of power divider, Lange coupler, and variable termination, is designed with each part fabricated separately using 0.15-µm GaAs pHEMT process and assembled on Rogers 5880 substrate with 10-mil-thick printed circuit board. The assembled vector modulator is characterized using an automatic test setup. The measured symmetric constellation is in good agreement with the simulation result, which indicates the effectiveness of the proposed design method and assembly process. INDEX TERMS Cold pHEMT, bond-wire, microwave integrated circuit (MMIC), parasitic elements, vector modulator.

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“…In this work, the equivalent circuit model of cold pHEMT proposed in [7] is utilized and shown in Fig. 3(a).…”

Section: A Cold-phemt Model Extractionmentioning

confidence: 99%

“…Consequently, the symmetry of constellation for vector modulator deteriorates and insertion loss is increased as well. To offset the amplitude imbalance of BVA, shunt resistor has been introduced in [7]. This method improves the mismatch but the minimum insertion loss is increased.…”

Section: Introductionmentioning

confidence: 99%

Performance Improvement of Microwave Vector Modulator Through Coupler Characteristic Impedance Optimization and Bond-Wire Inductance Utilization

Chen

Dilshad

Mehdi³

et al. 2019

IEEE Access

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“…To solve the problem, two main strategies are possible: the first one, reported in [18], is based on direct parasitics compensation, being therefore suitable for narrowband applications only; the second one is the balancing technique, mostly used for broadband applications [9][10][11][12][13][14][15][16][17].…”

Section: Traditional Vector Modulator Topologiesmentioning

confidence: 99%

A novel broadband MMIC vector modulator for V-band applications

Ciccognani

Ferrari

Giannini

et al. 2009

Int J RF and Microwave Comp Aid Eng

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In this study, a new vector modulator topology is presented. The modulator is composed by two ''balanced-load'' biphase modulators. The balanced load is a novel principle allowing a topological simplification of commonly adopted vector modulator schemes: seven couplers are used instead of the 9 ones in traditional reflection-type modulators, with comparable performance. The measured results of monolithic 45-65 GHz test vehicles of the methodology for both biphase and vector modulators, are presented.

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“…Only three elements, i.e., , , and are bias dependent. The gate contact resistance and inductance have little effect on terminal impedance since they are absorbed by a large gate biasing resistor, which makes the gate as open [6]. Let…”

Section: A Scalable Cold-phemt Modelmentioning

confidence: 99%

An Efficient Technique for Designing High-Performance Millimeter-Wave Vector Modulators With Low Temperature Drift

Hou¹,

Qiu

et al. 2008

IEEE Trans. Microwave Theory Techn.

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Recently the demand for high-performance low-cost vector modulators for millimeter-wave direct carrier modulation applications is increasing. An efficient technique to improve the performance of the vector modulators has been proposed in this paper accordingly. This technique highlights the effect of the Lange coupler characteristic impedance and the cold pseudomorphic HEMT (pHEMT) total gatewidth on the performance. It is demonstrated by investigating two types of vector modulators, which employ unbalanced and balanced topologies. Furthermore, to reduce the temperature drift, a concise analysis of the thermal behavior of the vector modulators has been carried out. Based on the proposed technique, two types of monolithic vector modulators have been realized at 40 GHz on a 100-m-thick GaAs substrate with 0.15-m cold-pHEMT devices. The static constellations were obtained by using an automatic measurement system, and the temperature drifts were characterized by the measurement data from 55 C to 70 C. The results show that the technique is suitable for millimeter-wave vector modulator designs. Index Terms-HEMT, millimeter-wave circuits, monolithic microwave integrated circuits (MMICs), vector modulator.

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Microwave I-Q vector modulator using a simple technique for compensation of FET parasitics

Cited by 17 publications

References 5 publications

Performance Improvement of Microwave Vector Modulator Through Coupler Characteristic Impedance Optimization and Bond-Wire Inductance Utilization

Performance Improvement of Microwave Vector Modulator Through Coupler Characteristic Impedance Optimization and Bond-Wire Inductance Utilization

A novel broadband MMIC vector modulator for V-band applications

An Efficient Technique for Designing High-Performance Millimeter-Wave Vector Modulators With Low Temperature Drift

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