Mandar R. Deshpande

X-band heterostructure interband tunneling FET (HITFET) VCOs

This paper reports on the DC and microwave performance of novel X-band voltage controlled oscillators fabricated by integrating heterostructure interband tunneling diode (HITD) with a heterostructure FET. The measured RF performance of VCOs incorporating single and double HITDs is discussed. The power output of the single HITD VCO was 2.0 dBm and that of the dual HITD was 4.3 dBm at a center frequency of 8.2 GHz. The dual HITD VCO also exhibited a wider tuning range than the single HITD VCO. The phase noise of these VCOs was approximately -128 dBc, 3 MHz away from the center frequency.

Microfabrication of two layer structures of electrically isolated wires using self-assembly to guide the deposition of insulating organic polymer

Abstract The fabrication of two layer structures of electrically isolated wire — crossed wire structures and a surface coil inductor — is described. The fabrication process utilizes the tools of soft lithography and incorporates two levels of self-assembly. The use of microcontact printing and patterned self-assembly of liquid polymers removes the need for registration of the insulating layer with the underlying layer as required in conventional lithography techniques. The performance characteristics of the surface coil inductor are measured and closely resemble those predicted by theory.

A comprehensive DC/RF tunnel diode model and its application to simulate HITFETs (heterostructure integrated tunneling FETs) and quantum-MMIC's

A comprehensive tunnel diode large signal model that incorporates the bias voltage dependence of its RF characteristics is developed. The model consists of a voltage controlled current source and is implemented in the Advanced Design System (ADS) simulation tool. This model is applied to simulate heterostructure integrated tunneling field effect transistor (HITFET) devices and circuits. HITFETs are quantum functional devices realized by monolithically integrating tunnel diodes and FETs. The enhanced functionality of a HITFET is utilized to design novel circuits with reduced complexity and size and having better performance. Many HITFET based circuits, such as voltage controlled oscillators, amplifiers, mixers, and antennas have been proposed and demonstrated. This new technology shows promise for portable communication applications and monolithic microwave integrated circuits (MMICs). This large signal model incorporated in ADS enables designers to simulate monolithic, multifunctional ICs containing tunnel diodes and HITFETs.

A MMIC lumped element directional coupler with arbitrary characteristic impedance and its application

In this paper the design technique for MMIC lumped element directional couplers, based on arbitrary termination impedance, is described. Arbitrary impedance terminations allow matching the linear and nonlinear elements to the coupler without the requirement of transformer networks. The techniques capability is demonstrated through the design of a single balanced mixer prototype at 1.8GHz for which measured and simulated data are provided.

Tunnel diode nonlinear model for microwave circuits and active antennas

Tunnel diodes have a unique property: negative differential resistance (NDR). The integration of tunnel diodes with other electronic devices creates novel, quantum functional devices and circuits. The enhanced functionality of these devices enables design of both digital and analog circuits with reduced complexity, size and better performance. In this paper we investigate the applications of a nonlinear, large signal model of the tunnel diode. This model is used to analyze tunnel diode characteristics under external conditions such as input RF signal and termination resistance. We also discuss the application of the model to simulate quantum-MMIC circuits. VCOs, and active antennas designed using tunnel diodes show power outputs in the range of -4 to -10 dBm in the 1-2 GHz band. The DC to RF conversion efficiency is about 8% in VCOs and 16% in the antennas.

A highly linear single balanced mixer based on heterojunction interband tunneling diode

In this paper a compact and highly linear MMIC single balanced mixer based on heterojunction interband tunnel diode (HITD) technology working at 1.8 GHz, is described. The prototype consisted of a pair of HITDs biased at zero volts and a lumped element directional coupler with arbitrary impedance terminations. The salient feature of the mixer is the linearity due to the quasi square law DC characteristics exhibited by the device around zero voltage. The design techniques along with a detailed experimental validation are provided. The prototype exhibited an IIP3 power level of 17 dBm and a 1 dB compression point of 7.5 dBm.

Analysis and design of active antenna arrays

In this paper, the FDTD method is extended successfully to analyze active antennas using Z-transform method for small signal model and by a stable scheme for large signal model. The two approaches are validated by comparison with analytical impedance expression in frequency domain. Through these approaches, we analyze active antennas and antenna arrays containing tunnel diodes. Effects of various device parameters are investigated in order to find desired oscillations. Single and array active antennas are designed and tested. Experimental and simulated results are given and compared.

Active antennas incorporating tunnel diodes-large signal model approach

In this letter, a comprehensive dc and RF model of heterostructure interband tunnel diodes (HITDs) is extracted. Active antennas incorporating tunnel diodes are analyzed in the time domain using this tunnel diode model. The simulated and measured results are in good agreement in terms of oscillation frequencies of the active antennas. Phase noise of -114.67 dBc/Hz @1.0 MHz offset is achieved for injection-locked active antennas. The simulated injection locking range of a Ka band active antenna array is investigated.

Integration of heterojunction interband tunnel diodes and HFETs for monolithic microwave circuits

Summary form only given. Three terminal devices that exhibit negative differential resistance (NDR) are actively being investigated for future use in high-speed, highly functional integrated circuits. While there is considerable research effort in the area of high-speed digital circuits, research on microwave applications of such devices is not being explored as aggressively. To date, transistors fabricated in the InAlAs-InGaAs lattice-matched to InP material system hold the records for RF performance. In recent years, heterojunction interband tunnel diodes (HITDs) in this same material system have shown excellent NDR behavior with measured peak-to-valley current ratios (PVCR) as high as 144 at room temperature and a corresponding peak current density of 200 A/cm/sup 2/, This makes the InAlAs-InGaAs-InP material system an excellent candidate for high-speed highly functional monolithic microwave integrated circuits. Here, we report on investigations of the integration of a heterojunction interband tunneling FET (HITFET), which consist of a HITD monolithically integrated with a HFET.

Quantum MMIC (QMMIC) VCO's for Wireless Applications

The monolithic integration of heterostructure tuneling diodes with other semiconductor devices, such as HFETs, creates novel, quantum functional devices and circuits. The enhanced functionality of these devices enables design of both digital and analog circuits with reduced complexity, smaller size and better performance. Several types of QMMIC VCOs operating in L-band frequency range have been designed and characterized. VCOs achieved output power of 8-10 dBm at L-band frequency range. All VCOs exhibited very low phase noise (in the range of ¿107 to ¿115 dBc/Hz) at 1.0 MHz away from the carrier frequency.