March 25, 2015
A critical component of a base station is the power amplifier (PA). Over the past two decades the PA has experienced monumental changes in its architecture and performance. Two significant improvements have been in power-added efficiency & bandwidth. Fifteen years ago a 2G basestation PA housed in a ground base station cabinet would output 5 MHz multi carrier CDMA signals at 40 W; running at 5% efficiency it would generate 760 W of heat, taking up a significant amount of space, power and cooling resources and costing thousands of dollars. Today's 4G amplifiers using Doherty architecture with predistortion has improved the efficiency of an amplifier to over 35%, significantly reducing the size and enabling integration of the PA with the transceiver and the duplexer into a remote radio head (RRH) placed near the antenna.
March 25, 2015
This paper offers a description of a process to change the operating frequency range of an existing power amplifier circuit using only Smith chart and transmission line calculation software, demonstrating that experimental tuning and review with a Smith chart can avoid the possibility of creating an untenable design. It also addresses the possibilities of applying this approach to other RF power outputs, frequency range conversions and bandwidth extensions, as long as several key caveats are observed.
March 2, 2015
Achieving sufficient capacity to meet the forecast backhaul needs over the next few years will be a major challenge. This white paper describes the technique of Air Division Duplexing (ADD), which makes use of MIMO and spatial multiplexing techniques to achieve simultaneous transmission and reception of data on each carrier frequency, and has been shown to achieve full duplex data rates1 in excess of 1 Gb/s in a 28 MHz channel
allocation2 in the microwave bands.
February 19, 2015
While LTE-Advanced brings the promise of higher data rates, designing devices for use in LTE-A offer new test challenges. This paper provides an overview of LTE MIMO and carrier aggregation technologies and describes different methodologies for testing these new capabilities including multi-antenna techniques, MIMO spatial multiplexing, beam steering, as well as the different carrier aggregation modes.
January 15, 2015
Metrigraphics' thin film process is a fundamental technology uniquely suited to the task of making miniature circuits with extremely small and uniform features that have extremely consistent electrical performance throughout. The process also tends to be much faster and less wasteful than subtractive manufacturing methods like chemical etching. That's because only the conductive material needed to define the circuit geometry is being deposited, which results in in a manufacturing process that is more efficient and less wasteful.
January 15, 2015
Semiconductor manufacturing test engineers face challenges related to broadband millimeter wave (MMW) on-wafer testing. Achieving accurate, stable measurements, typically performed using VNAs, over extended time periods is a challenge for foundries and fab-less semiconductor companies that require extensive on-wafer devices testing. This paper examines the impact of calibration downtime during on-wafer testing and recent advances enabling longer time periods between calibrations.
December 15, 2014
This white paper discusses the design of power amplifiers employing Cree GaN HEMTs and NI AWR Design Environment / Microwave Office circuit design software to maximize power-added efficiency (PAE) by optimizing source and load pull at both fundamental and harmonic frequencies. The load-pull scripts within Microwave OfficeÃ?Â are used to find the optimum trade-offs in power gain, efficiency, and stability. The article describes the basis of Class F PA and inverse Class F design F, as well as a new approach called continuous Class F, which enables greater bandwidths to be realized. Several practical design examples are given, including the inspection of voltage and current waveforms for both packaged and bare die transistors in the 10 to 25 watt power range for frequencies up to 2.5 GHz. In addition, the ways in which the Microwave Office load pull wizard can be used to investigate fundamental and harmonic impedances both at the input and output of transistors are discussed.
December 15, 2014
Innovation that's Open - Introducing OpenRFM. Meeting new government interoperability and affordability requirements in Electronic Warfare and Signals Intelligence, requires innovative approaches in advanced RF/Microwave and digital signal processing. OpenRFM is the first RF/Microwave open system approach that leverages best available commercial-item technology to deliver sophisticated, interoperable sensor processing subsystems to dominate the electromagnetic spectrum. OpenRFM is the better alternative for affordable RF subsystems for our war fighters and allies alike.
November 17, 2014
For decades, spectrum analyzers have been used to develop and characterize radar and electronic (EW) warfare systems. However, traditional swept measurements are rapidly becoming insufficient because most modern radar systems are adaptive. Learn about methods for monitoring EW scenarios, identifying unwanted events in the transmitted waveform, and accurately measuring found signals.Ã?Â