Wojciech Wojtasiak

The 100W class A power amplifier for L-band T/R module

A balanced high-power amplifier with class A silicon bipolar transistors for an L-band T/R module for active phased array radar is described. The amplifier was designed for maximum power and minimum transmittance distortion. The obtained parameters of the amplifier are as follow: output power at 1dB compression P/sub 1 dB/>49 dBm, linear gain |S21|>10 dB, and transmittance deviations during the RF pulse: phase /spl Delta/arg(S21)<0.9/spl deg/ and /spl Delta/P/sub out/< 0.2 dB.

A S-band 7 W GaN HEMT adaptive power amplifier

In the paper a 7 W GaN HEMT adaptive power amplifier (APA) operating over 1.8 to 4.0 GHz is presented. To control APA states the six pin diodes as regulators have been used in both input and output matching networks. The design is based on the small-signal approach for modelling active elements such as transistor and regulators. The measured results of APA have proven usefulness of the proposed design methodology. The APA is controlled by specialized unit - Universal Controller of Adaptation.

Temperature-dependent modeling of high power MESFET using thermal FDTD method

A temperature-dependent model of high power MESFET based on the small signal extraction methodology is presented. The temperature dependencies of the MESFET equivalent circuit elements derived from experimental results describing long-term thermal effects and short-term thermal effects have been modeled by means of FDTD method using chip dimensions. The verification of the proposed model shows an excellent agreement of the experimental results with the theoretical analysis.

An ultrawideband 1 to 6 GHz 0-IF radio receiver with 500 MHz of instantaneous bandwidth

This paper is related to the project of an ultrawideband radio receiver operating between 1 and 6 GHz with instantaneous bandwidth of 500 MHz. A single frequency conversion (0-IF) architecture is based on analog I/Q demodulator (ADL5380) and two channel 14-bit analog-to-digital converter (AD9680). Preliminary measurements of the receiver have been performed and presented in the paper. Key results include: noise figure NF < 7.5 dB, dynamic range over 62 dB (enhanced by frontend and baseband leveling circuitry), high linearity: IIP3 > 21 dBm.

Low phase noise synthesizer optimized for wideband 0-IF radio receiver

In this paper the performance of two wideband PLL frequency synthesizers realized with ADF5355 and HMC833 chips respectively has been compared. Both of them were investigated as a local oscillator for 0IF receiver operating from 1 GHz to 6 GHz. In order to provide required harmonics level below -40 dBc the final solution is based on the ADF5355 followed by a switched bank of four low pass filters. The phase noise level is better than -90 dBc @ 1 kHz and spurious are lower than -70 dBc.

A DC analytical AlGaN/GaN HEMT model for transistor characterisation

In this paper an analytical model is developed to characterize the performance of GaN-based microwave HEMTs. To theoretically predict mobility and sheet carrier concentration in 2-dimentional electron gas (2DEG) of GaN HEMTs extraction procedure is proposed. Presented model is based on physical relationships and I–V characteristics without introducing any semiempirical parameter. Results are compared to experimental data achieved from C-V and Hall measurements. Proposed model is found to be useful for device designers to rapid assess the process quality without the use of additional measurements that require previously applied probes.

Design of dual-band bandpass filters using cross-shaped resonator and spurline

This paper presents a microstrip dual-band bandpass filter (BPF) based on cross-shaped resonator and spurline. It is shown that spurlines added into input/output ports of a cross-shaped resonator generate an additional notch band. Using even and odd-mode analysis the proposed structure is realized and designed. The proposed bandpass filter has dual passband from 1.9 GHz to 2.4 GHz and 9.5 GHz to 11.5 GHz.

Design of ultra-wideband bandpass filter with two reconfigurable notches using terminated cross-shaped resonator

An ultra-wideband (UWB) bandpass filter (BPF) with two reconfigurable notch bands is proposed, based on cross-shaped resonator (CSR) without using coupled line structure. With the use of even and odd-mode approaches, the proposed UWB bandpass filter bandwidth is from 2.8-10.9 GHz, with 118% fractional bandwidth (FBW), and the dual reconfigurable notch bands is tuned from 4-5.3 GHz, and 7.9-8.8 GHz.

Transverters for TDD and FDD ISM 2.4GHZ Radio Systems

The paper describes development of a technique and equipment to convert signals from TDD or FDD radio systems operating over popular ISM 2.4 GHz-band up to the less crowded, licensed 3.5GHz or 4.4GHz bands. The technique of bands conversion consists in a connection to the existing infrastructures RF up/down converter modules (transverter) with T/R switches or duplexer for TDD or FDD systems, respectively. Currently, the 3.5GHz FDD transverters cooperate in 17 locations with the IRT2000 digital radio access system used by El-net NETIA group and 4.4GHz TDD transverters work together with 802.11b WLAN AP utilized by Military Communication Institute.

A 100W ISM-2.45GHz band power test system

This paper describes development of solid-state microwave power test system (MPTS) operating over 2.3 to 2.6 GHz with the output power level of 100 W for industrial applications in material processing, and for designing of microwave power industrial equipment. The MPTS unit consists of four major parts: PLL synthesizer, high power solid-state amplifier, detector probes for return losses and leakage measurement and microcontroller. The MPTS system is able to operate in either single fixed-frequency regime, or in swept mode with self-tuning for minimum reflection of a heated load.