E. Bergeault

Power amplifier characterization: an active load-pull system based on six-port reflectometer using complex modulated carrier

An original measurement system for nonlinear RF power-transistor characterization is presented. This new setup enables measurement and optimization of output power, power-added efficiency (PAE), or linearity using active fundamental tuning and six-port reflectometers as vector network analyzers. High- and low-frequency bias-tees are inserted at both ports of transistors in order to control source and load impedances at the baseband (envelope) frequency. Experimental results at 1.575 GHz show an adjacent channel power ratio improvement of 20 dB for a commercial GaAs MESFET power transistor operating in class AB. Moreover, the output power and PAE are increased by 1 dB and ten points, respectively

Microwave Measurement using Wheatstone's Bridges

This paper presents the design of Monolithic Six-Port Module MSPM with resistive bridges. It shows how these simple structures may act as directional resistive couplers. Final MMIC circuit includes six-port junction and matched MESFET detectors covering an area of 1.2 mm2 in the frequency range 100 MHz to 3 GHz. The MSPM was bonded in a MIC structure with output coaxial connectors or inside the tips of a probe station. In this last case, the MSPM acts as an active probe. Experimental results obtained using a commercial network analyzer and our measurement system are in good agreement.

A new structure for a six-port reflectometer using a silicon MOSFET for power measurement

This paper presents a new structure for silicon MMIC sixport reflectometer. Its originality lies in the use of a newly developed power detector using a silicon MOSFET transistor as an alternative to the commonly used biased Schottky diode detector. The power detector using a nonbiased MOSFET transistor has demonstrated a better sensitivity than the Schottky diode detector counterpart. The six-port reflectometer calibration uses minimum of five loads with an unknown but constant absolute value of the reflection coefficient and unknown but well-distributed phases. The circuit has been fabricated in silicon MMIC technology working between 0.9-3.0 GHz. A thorough comparison of the measured data with a commercial network analyzer is presented.

A source-pull/load-pull measurement system including power amplifier linearization using simple instantaneous memoryless polynomial base-band predistortion

In this paper, an original measurement system for non-linear power characterization is presented. This set-up enables optimization of output power or power added efficiency (PAE) in conjunction with transistors linearization. The optimization of the fundamental impedances is performed using source-pull/load-pull measurements before a base-band predistortion is carried out. The linearization method for complex modulated carrier is based on the measurement of the instantaneous AM/AM characteristic and on the measurement of the AM/PM conversion. Therefore, an instantaneous memoryless polynomial base-band predistortion is obtained. Experimental results at 1.575 GHz for a commercial GaAs MESFET transistor biased in class AB show improvements equal to 15 dB and 5 dB for the C/I3 and ACPR values, respectively

New structure for a six-port reflectometer in MMIC technology

This paper presents a new structure for a six-port reflectometer which due to its simplicity can be integrated very easily in MMIC technology. It uses non-matched diode detectors with a high input impedance that are placed around a phase shifter. The circuit has been fabricated by the foundry GEC-Marconi and operates between 1.4 and 2.5 GHz.

The design of a six-port reflectometer with frequency-independent calibration procedure

The accuracy in the measurement of an unknown reflection coefficient using a six-port automatic network analyzer (ANA) depends in part on the stability of the calibration constants of the system. A six-port reflectometer whose configuration minimizes the variations of these parameters with frequency is described. The advantages of a six-port configuration include a weakly and slowly frequency-dependent calibration process. Consequently, uncertainties due to the variations of the six-port parameters with RF-source stability are reduced. There is no need for a synthesized source, and the number of calibration points can be reduced while the symmetrical distribution of the q/sub i/ points can be kept over the whole frequency range.<<ETX>>

Source-pull and multiharmonic load-pull measurements based on six-port techniques

An original measurement system for nonlinear microwave power transistor characterization, using six-port reflectometers, is presented. It allows independent active tuning of the output impedances at f/sub 0/ and 2f/sub 0/ (multiharmonic load-pull) and variation of the source impedance at the input port at f/sub 0/ (source-pull). Experimental results are shown for a commercial GaAs MESFET power transistor.

MMIC quasi-circulator with low noise and medium power

This paper presents the design and the measured performances of a narrow band quasi-circulator module. Its design implements active divider and combiner. The device demonstrates a noise figure of 5.5 dB and an output power of 18 dBm with associated gains of 4 dB and 7.6 dB for the receive and transmit path, respectively.

Experimental Characterization of Power Transistors for Linearity Optimization

In this paper, different techniques are combined in a unique characterization system dedicated for power transistor linearity improvement. Successive optimizations are performed using source-pull/load-pull techniques at the fundamental and base-band frequencies associated with an instantaneous memoryless base-band predistortion procedure. Measurement results performed at 1.575 GHz on a MESFET power transistor biased in class AB for a QPSK modulated signal, show that fundamental frequency source-pull measurements lead to an ACPR variation equal to 3 dB. Moreover, the influence of base-band impedance on ACPR and EVM is found to be 15 dB and 4.5 points, respectively. Finally, instantaneous memoryless base-band predistortion improves ACPR and EVM values by 5 dB and 1 point, respectively.

An automated multiharmonic source-pull/load-pull system based on six-port techniques

We have improved our existing Source-Pull/Load-Pull setup to allow independent active tuning, both at fundamental and second harmonic frequency, of the load and source impedance of the device-under-test (DUT). We will present experimental results to validate the calibration procedure and to show the accuracy of the measurements.