Conferences

A 9-10GHz 25W GaN Quasi-MMIC PA in QFN Package

A single stage X-band (9-10GHz) PA module has been developed using a discrete 0.25um GaN transistor with 4.8mm gate periphery, that incorporates input and output matching via discrete substrates in package. The initial demonstrator module achieves 25W of power under pulsed conditions at 9.5-10GHz with Vds=40V, a peak efficiency of 44% and small signal gain of around 12dB. The PA was assembled in a 5mm overmolded QFN package. The power density and peak drain efficiency are in reasonable agreement with the process pcm performance at this frequency, given output matching losses have to be accounted for. This work demonstrates the feasibility of prematched GaN transistors and MMIC-like modules in high volume SMT packaging and to a frequency of 10GHz.

ADC Considerations in RF System Design

Broadband Analog to Digital Converters (ADCs) are key building blocks in modern receiver design. Although broadband ADCs share some “traditional” parameters and design rules which are similar to conventional analog blocks in the RF chain, they also introduce their own set of unique behaviors and design rules caused by sampling and quantization.

This presentation from test equipment rental provider Interlligent UK (VNA rental,spectrum analyser rental and signal generator rental) will discuss some of these unique attributes and their influence on RF system design. It will cover the ADC’s dynamic range and how this effects the performance and design choices for the whole RF Front end, Real-IF and Zero-IF receiver frequency plans, linearity budget and noise budget. It will also review some popular ADC architectures used in receivers and discuss the relative merits.

Calibration of an Anechoic Chamber for Measurement of a Multi-Channel Antenna

Anechoic chambers are structures which simulate testing in free space and are used to measure the radiation pattern of an antenna. This paper presents a methodology to measure the radiation properties and hence determine the gain of a multi-channel antenna in an anechoic chamber. This gives an unique extension to current practice that is only suitable for a single channel antenna. The process to measure the loss through an anechoic chamber measurement system and the gain measurement of a multi-channel antenna are presented and a measurement procedure is recommended.

Ka-Band 4W Power Amplifier MMIC

The measured performance of a Ka-band power amplifier MMIC is presented. The MMIC was fabricated using a 2mil 0.15um GaAs pHEMT process. The design achieves saturated output power in excess of 36dBm over a bandwidth of 32 – 38 GHz, with a PAE of 23%. The part specifications exceed competitor performance in terms of chip size ratio and power. The measurement reference plane includes the bond wire transition on and off the die with a probable substrate used for test.

Non-Binary Power Dividers

Most power dividers are binary in that they offer 2, 4, 8 or 16 way division of the input signal.
The reason for this is that every junction is a 1:2 split which makes it easy to achieve an equal amplitude and phase balance. However, if the requirement is for a 3-way, 5-way or 10-way power division then the design can either use a binary division and terminate the extra outputs, which wastes power, or a junction must be designed that can provide a 1:3 split or a 1:5 split with equal amplitude and phase balance. This paper describes how to do this with the use of a planar electromagnetic simulator.

Second Harmonic Extraction of Planar Gunn Diode by Using Resonators for Millimetric Wave Applications

Indium gallium arsenide (InGaAs) planar Gunn diodes with on chip matching circuits were fabricated on a semi-insulating Indium phosphides (InP) substrate. Radial and diamond stub resonators were used as circuit elements to suppress the fundamental frequency and allow the second harmonic frequency to be extracted from the planar Gunn diode. The extraction of the second harmonic will enable the planar  Gunn diode to operate at millimetre wave and terahertz frequencies. InGaAs planar Gunn diodes were fabricated with an active channel length (anode to cathode separation) of 4 µm and a width of 120 µm. The  experimental results gave a second harmonics signal at 118 GHz with an RF output power of -20 dBm for the radial stub resonator, and 121 GHz with an RF output power of -14.1 dBm for the diamond stub resonator. This is the highest second harmonic power recorded for a planar Gunn diode. The results indicate the potential of terahertz operation by reducing the channel length to sub-micron and extracting the second or third harmonic from the planar Gunn diode.

Submillimeter Rectangular Waveguides Based on SU8 Photoresist Micromachining Technology

Rectangular waveguides are fundamental structures for transmission of signals and for the construction of passive circuits. This paper describes the design and measured results for two rectangular waveguides based on SU8 photoresist micromachined technology, with double-layer fabrication and partial coating techniques to minimise the air gaps between layers. A brief description of the SU8 photoresist micromachining procedure is given in the paper. One waveguide is demonstrated for the WR3 band from 220 GHz to 325 GHz, which is made of SU8 photoresist with a novel 3 piece construction with top and bottom two layers joined to form the whole 5 layers structure. The other is for the WR6 band 120 GHz-170 GHz with a new 3 pieces construction assembly with a 5 layer structure. Both waveguide have novel bends in order to connect the measurement apparatus. The measured performance is presented and compared to conventional machined metal waveguide structures. The measurement results of insertion loss show both waveguides are better than 0.03 dB/mm.

What are the Limits to Increasing the Dynamic Range of RF ADCs?

This paper puts forward a figure of merit concept that relates ADC data sheet specifications to RF performance. It will indicate where future trends exist and outline a signal processing method that enables resolution in bits to be traded for sampling frequency while maintaining the figure of merit.  The paper will also review the effectiveness of signal processing methods in increasing spurious free dynamic range.