Seppo Kangasmaa

Six-port Direct Conversion Receiver

The applicability of the known six-port receiver structure for mobile phones was studied. The six-port receiver is typically used in high frequency microwave analyzers where a wide bandwidth is required. In these applications the unperfections of the six-port structure can be canceled by using calibration. In direct conversion receivers a severe problem is to achieve the required AM suppression characteristics. This is known as a DC problem. Strong adjacent channel signals cause interference in the baseband through second order effects. To evaluate the suitability of a six-port receiver to achieve the required AM suppression level a discrete component six-port receiver operating at 2GHz frequency area was implemented and measured. The results were compared against traditional mixer structures.

Analysis of packaging effects and optimization in inductively degenerated common-emitter low-noise amplifiers

The effects of packaging on the performance of inductively degenerated common-emitter low-noise amplifiers (LNAs) are examined and the equations describing the input impedance, transconductance, voltage gain, and noise figure of the packaged amplifier are derived. From the equations, several guidelines for the LNA design are obtained and a systematic approach for the LNA design can be derived. Furthermore, by applying the formulas, the performance of the amplifier can be readily estimated and optimized in the very early stage of the circuit design, immediately as the process data is available. The measurement results of the implemented 0.35-/spl mu/m SiGe RF front-end with an inductively degenerated common-emitter LNA at 1.575 GHz agree well with calculations and simulations.

Modeling of 3D packages using EM simulators

This paper discusses the modeling of 3D electronic packages. A 3D model of a stacked die package solution is built and analyzed in a 3D electromagnetic (EM) simulation tool, and a lumped element RLC equivalent model is extracted. The challenges and possibilities of EM simulation are discussed. The parasitic components of the package are studied by analyzing the 3D model by parts. Strategies in specifying a Spice net list of the package model and its feasibility in circuit simulations are considered.

Low-Noise VLBI Receiver at 22 GHz for Radioastron Satellite: Progress Report

The progress made in the 22 GHz low-noise Radioastron receiver project is described in this report. In this project a receiver for satellite VLBI radio astronomy is being designed and constructed. The LNA utilizing HEMTs will be cooled to 80 K, the other parts of the receiver including a phase-locked LO at 21.72 GHz, down-conversion to 512 MHz IF, total power detector and noise injection calibration system stay at 300 K physical temperature. First measurements show a noise temperature of 100 K for the LNA at 80 K.