Avtar S. Virdee

A novel high efficiency multioctave amplifier using cascaded reactively terminated single-stage distributed amplifiers for EW system applications

This paper demonstrates the design of a high efficiency amplifier employing a novel concept of cascaded reactively terminated single-stage distributed amplifier (CRTSSDA). In addition, CRTSSDA produces an available power gain significantly higher than conventional distributed amplifiers using the same number of active devices. Three-CRTSSDAs were designed and fabricated for EW application. The novel amplifier achieved an associated gain above 26 dB with flatness of </spl plusmn/0.5 dB, an average power added efficiency in access of 27% at an output power of 25 dBm over the 2-18 GHz band with an efficiency peak of 30% at 12 GHz.

Cascaded single-stage amplifier with improved gain-frequency performance using frequency-dependent lossy artificial lines

The gain-frequency performance of the cascaded single-stage distributed amplifier (CSSDA) configuration, which was designed for power application, is considerably improved in terms of significantly reduced in-band gain ripple without compromising its bandwidth. This is achieved with the incorporation of passive components within artificial transmission lines constituting the CSSDA so that it exhibits frequency-dependent loss behaviour.

Bandwidth and Efficiency Improvements in Cascaded Single-Stage Distributed Amplifier

This paper first demonstrates the viability of the cascaded single-stage distributed amplifier (CSSDA) implementation using discrete packaged HJ-FET devices. The design is shown to provide superior performance in terms of available power gain than conventional distributed amplifiers (CDA) using the same number of active devices. Next modifications to CSSDA design by employing reactive terminations is shown to render the amplifier suitable for large-signal operation, and this significantly improves the amplifiers overall performance. The novel distributed amplifier implemented using DHEMPT devices achieved an associated gain above 26 dB with flatness of < 0.5 dB, an average PAE in access of 27% at an output power of 25 dBm over a multioctave bandwidth of 2-18 GHz with an efficiency peak of 30% at 12 GHz. The CSSDA is suitable for digital optical communication and pulse applications.

Single-ended amplifier that substantially improves PAE and ultra-broadband performance

A single-ended amplifier with a simple reactive matching is shown to provide stable operation with substantially improved amplifier power-added efficiency (PAE) (>30%) across an ultra-broadband frequency range (2-18 GHz). The amplifier employs a Double Pseudomorphic High Electron Mobility Transistor (DPHEMT) power device.A single ended amplifier with a simple reactive matching is shown to provide stable operation with substantially improved amplifier power-added efficiency (PAE) (>30%) across an ultra-broadband frequency range (2-18 GHz). The amplifier employs a Double Pseudomorphic High Electron Mobility Transistor (DPHEMT) power device.

Novel Current Sharing Concept Improves Efficiency of Broadband Feedback Amplifiers

This paper describes the concept of current sharing in order to reduce the current consumption of hybrid MIC broadband amplifiers and improve the overall efficiency of the subsystems that employ the amplifiers. Current sharing technique was implemented on a 2-18 GHz cascaded two-stage feedback amplifier and a 2-4 GHz balanced amplifier. The experimental results presented demonstrated that the current sharing concept drastically reduces the current consumption by 50 percent without compromising the amplifier performance in any way. The consequence of this is a two-fold improvement in the power-added efficiency.

Data Modulator Driver Broadband Amplifier

Ultra-wideband amplifiers covering kHz to GHz are critical components as data modulator drivers in fiber-optic transmission systems. This paper presents the design and development of a 30 kHz to 20 GHz data modulator driver amplifier that supports transmission of data rates from 2.5 Gb/s to 20 Gb/s, and highlights the manufacturing implementation of the amplifier.

Bandwidth Extension Of A Conventional Distributed Amplifier

This paper presents a unique technique for significantly improving the bandwidth of a conventional distributed amplifier (CDA) using negative resistance. It is demonstrated that by making the gate-line of the CDA configuration negative resistance, the amplifiers operational bandwidth is improved by 14% without compromising its gain performance. In this case the 4-stage CDA was implemented using packaged pseudomorphic HJ-FET devices. The simplicity of the proposed technique makes it amenable to MMIC technology.

Targeted Suppression of Spurious Responses in Microstrip Bandpass Filters

This paper demonstrates how spurious responses of planar microstrip-line bandpass filters can be effectively and selectively suppressed. This is achieved by exciting a lambda/2 microstrip-line resonator at appropriate points dictated by the standing wave nulls of the E-field established on the line corresponding to the relevant resonant mode to be eliminated. Excitation is achieved via distributed capacitance instead of chip capacitors, hence saving time and cost for practical realization. The work in this paper has been confirmed with practical results.

Broadband Limiting Amplifier for Instantaneous Frequency Measurement System

This paper describes the design and implementation of a 90 dB limiting amplifier, which can operate across 6.5 to 18 GHz, for application in instantaneous frequency measurement systems (IFM). It employs a novel amplifier configuration comprising of a combination of cascaded reactively terminated single-stage distributed amplifiers (CRTSSDA) and negative feedback amplifiers (NFA). The amplifier exhibits exceptional gain flatness with small-signal suppression performance better than 90% across 6.5 to 18 GHz. The specially developed alumina substrate makes the amplifier design ideal for high volume manufacture using automated processes

Open-Loop Folded Ring Mimics Photonic Band-Gap Device

An open-loop folded microstrip ring resonator is practically demonstrated to exhibit a photonic band-gap (PBG) phenomenon. This is due to the fact that impedance discontinuity at the gap introduces multiple reflections with phase correlation that generates a PBG response. The physical dimensions of this device are significantly smaller than other conventional microstrip PBG structures. Such a device can be easily integrated with other microwave devices without severely affecting space requirements