Mattias Ingvarson

A distributed heterostructure barrier varactor frequency tripler

We present a broadband nonlinear transmission line (NLTL) frequency multiplier at F-band. The multiplier consists of a finline section periodically loaded with 15 heterostructure barrier varactor (HBV) diodes. Tapered slot antennas are used to couple the fundamental signal from a WR-22 rectangular waveguide to the distributed multiplier as well as radiate the output power into free space. The frequency tripler exhibits 10-dBm peak radiated power at 130.5 GHz with more than 10% 3-dB bandwidth and 7% conversion efficiency. The tripler can be used as an inexpensive broad-band solid-state source for millimeter-wave applications.

Thermal constraints for heterostructure barrier varactors

Current research on heterostructure barrier varactors (HBVs) devotes much effort to the generation of very high power levels in the millimeter wave region. One way of increasing the power handling capacity of HBVs is to stack several barriers epitaxially. However, the small device dimensions lead to very high temperatures in the active layers, deteriorating the performance. We have derived analytical expressions and combined those with finite element simulations, and used the results to predict the maximum effective number of barriers for HBVs. The thermal model is also used to compare the peak temperature and power handling capacity of GaAs and InP-based HBVs. It is argued that InP-based devices may be inappropriate for high-power applications due to the poor thermal conductivity of the InGaAs modulation layers.

A 100-GHz HBV frequency quintupler using microstrip elements

A new quintupler concept using a heterostructure barrier varactor has been fabricated and measured. The multiplier consists of a quartz circuit mounted in a full height crossed waveguide block, and hence uses a mixture of waveguide components and microstrip elements. The embedding impedance for the fundamental frequency is provided by tuneable backshorts, whereas conventional microstrip circuit elements are used for impedance matching for the third and fifth harmonic. This topology is highly suitable for monolithic integration, and a peak conversion efficiency of 4.9% was measured at 102.5GHz with an input power of 13dBm.

High power HBV multipliers for F- and G-band applications

Progress and realisation of applications in the 100-240 GHz region is inhibited by the lack of high-power sources. Therefore, in an effort to reach watts of output power, we have tailored devices, circuits, materials, and design and fabrication methods for improved thermal management and high overall conversion efficiencies.

A low cost fixed tuned F-band HBV frequency tripler

We present a novel fixed tuned heterostructure barrier varactor diode (HBV) tripler. This new multiplier consists of a microstrip section, which provides the critical impedance matching, and the diode, connected to microstrip to waveguide transitions at each end. The circuit is inserted in the E-plane of a waveguide mount, and both the input (Q-band) and the output (F-band) waveguide to microstrip transitions are realized using antipodal finlines. A peak efficiency of 4.2% with a 3% 3-dB bandwidth at 3/spl times/42.6 GHz for an input power of 13 dBm has been measured.