Adolfo C. Reyes

Coplanar waveguides and microwave inductors on silicon substrates

Silicon has many advantages as a microwave substrate material including low cost and a mature technology. The aim of this paper is to evaluate the potential of using high-resistivity silicon as a low-cost low-loss microwave substrate through an experimental comparative study. Coplanar waveguides fabricated on Si, GaAs, and quartz substrates are tested and their characteristics are compared. Microwave spiral inductors and meander lines are also fabricated on various substrates, and their performance is also analyzed. The results demonstrate that the losses of a coplanar transmission line (CPW) realized on high-resistivity (3 k to 7 k /spl Omega/-cm) silicon substrates are comparable to the losses of a CPW realized on a GaAs substrate covered with insulators. Furthermore, measured unloaded Qs of microwave inductive structures on high-resistivity silicon substrates are comparable to the measured unloaded Qs of the same structures on GaAs and on quartz. This paper demonstrates that high-resistivity Si can be used as a microwave substrate. >

Silicon as a microwave substrate

Silicon has many advantages as a microwave substrate material including low cost and a mature technology. The lower resistivity of Si (/spl ap/10 k /spl Omega/-cm) compared to GaAs (/spl ap/10 M /spl Omega/-cm) is perceived as a major disadvantage. In this paper, we present measured and simulated results demonstrating that the losses of a coplanar transmission line (CPW) realized on silicon substrates are comparable to the losses of a CPW realized on a GaAs substrate with insulators. The loss mechanisms of Si and GaAs substrates used for microwave applications are analyzed using both microwave and semiconductor physics theory. A high resistivity Si substrate can be used both as a microwave substrate and an active element carrier permitting further integration at low cost.<<ETX>>

High resistivity Si as a microwave substrate

Silicon has many advantages as a system substrate material including low cost and a mature technology. However, Si has not been demonstrated as a good microwave substrate compared to semi-insulating GaAs or quartz. The aim of this paper is to evaluate the potential of using high-resistivity silicon as a low-cost low-loss microwave substrate through an experimental comparative study. Coplanar waveguides fabricated on Si, GaAs and quartz substrates are tested and their characteristics are compared. Microwave spiral inductors and meander lines are also fabricated on various substrates, and their performance is also analyzed. The results demonstrate that the losses of a coplanar transmission line (CPW) realized on high-resistivity (3 k to 7 k /spl Omega/-cm) silicon substrates are comparable to the losses of a CPW realized on a GaAs substrate covered with insulator. Furthermore, measured unloaded Qs of microwave inductive structures on high-resistivity silicon substrates are comparable to the measured unloaded Qs of the same structures on GaAs and on quartz. The measured results are explained using both microwave and semiconductor physics theory. This paper demonstrates that high-resistivity Si can be used as a microwave substrate.

High performance single supply power amplifiers for GSM and DCS applications using true enhancement mode FET technology

Two high performance single supply power amplifier IC products have been developed for GSM and DCS applications using true enhancement mode FET technology. At VD=3.2V, under CW conditions, the GSM IC supplies +35.5 dBm output power at 58% PAE and the DCS IC supplies +33.5 dBm at 46% PAE. These ICs have low leakage currents similar to HBT and LDMOS and do not require the use of a drain switch. In addition, due to a high threshold voltage (Vth=+0.6V), they exhibit excellent RF isolation at Vref=0.1V and Pin=+5 dBm and do not require on-chip attenuators.

RF/microwave flip chip technology

Summary form only given. An alternate approach to wire bond interconnects is flip chip technology. Ultimately, coplanar waveguide rather than microstrip transmission lines are utilized in the die and package designs. The metrology of characterization and measured results of RF/microwave circuit elements under flip chip conditions are addressed.<<ETX>>

Theoretical and experimental investigation of bias and temperature effects on high resistivity silicon substrates for RF applications

Theoretical and experimental comparisons show that the RF characteristics of a CPW in Schottky contact with a HR Si substrate are bias independent for all practical temperatures, up to 100/spl deg/C. Bias dependence on the RF characteristics of the transmission line are noticed above 100/spl deg/C when the ohmic dielectric loss of the HR Si becomes the dominant loss mechanism on the coplanar structures under study. This is a direct result of the increase of intrinsic carrier density.

Temperature and bias effects in high resistivity silicon substrates

The purpose of this paper is to report the results of studies dealing with the impact of temperature and DC bias on low-cost low loss high resistivity (HR) Si substrate. Measured results show that microwave performance of a coplanar transmission lines and a meander inductive structure realized on HR Si are not affected by applied DC bias from -10 V to 10 V in the temperature range from -50/spl deg/C to 50/spl deg/C. Furthermore, measured results demonstrate that the losses of the structures under study on HR Si are comparable to the losses of similar structures on semi-insulating (SI) GaAs up to 100/spl deg/C.

Microwave Inductors on Silicon Substrates

Microwave inductive structures are fabricated on high resistivity (3 k to 7 k ¿-cm, measured) Si, GaAs, and quartz substrates under two conditions: metal-substrate and metal-insulator-substrate. The insulators are sandwiches of: SiO2(field)/Si3N4 and SiO2(field)/Si3N4 with SiO2(gate). The measured unloaded Q of single layer spirals and meander inductors on Si substrates are comparable to the measured unloaded Q of the same structures realized on GaAs and quartz substrates. These results are in agreement with the ones obtained using coplanar transmission lines (CPWs), which further confirm that high resistivity Si can be used as a microwave substrate.