RF flip-module BGA package

We recently described a flip-chip package with integrated thin-film inductors and capacitors in a VCO tank circuit of a single chip GSM transceiver integrated circuit (IC). By embedding the passive components in a Si-on-Si substrate, we eliminated spurious resonances that were caused by the parasitics of the original 64-TQFP IC package. However, compared with the bare die, the resultant Si-on-Si structure is larger in all dimensions due to the inclusion of a flip-chip mounted transceiver IC and a surface-mount varactor. We have developed a novel BGA package structure with a hole milled in the center to accommodate the silicon-on-silicon assembly. The interconnections rely exclusively on flip-chip solder technology. To verify that the package does not degrade the performance of the RF circuits, we have performed electromagnetic field simulations to extract critical inductance and capacitance parameters. Parasitic inductances of the original TQFP and the new packages are comparable due to their similar dimensions. None the less, a major advantage of the new package structure is that it permits the integration of key passive components inside the package where they are unaffected by package parasitic impedances     

Synthesis and Characterization of Octapeptide Somatostatin Analogues with Backbone Cyclization: Comparison of Different Strategies,Biological Activities and Enzymatic Stabilities

Somatostatin octapeptide analogues of the general sequence DPhe⁵‐Phe ⁶‐Tyr⁷‐DTrp⁸‐Lys⁹‐Val¹⁰‐Ph ¹¹‐Thr¹²‐NH₂ containing two types of backbone cyclization have been synthesized by the solid phase methodology. Backbone cyclization in these peptides was achieved via N‐modified phenylalanines in position 6 and 11. The N‐modified amino acids were incorporated as dipeptide building units which have been prepared in solution prior to the solid phase synthesis. Two dipeptide units of structure a) Fmoc‐aa ₁ ψ[CO—N((CH₂)_n‐X)]Phe—OH or b) Fmoc‐aa₁ ψ[CH₂—N(COlpar;CH₂)_n‐X)]Phe—OH have been introduced into the peptide sequence. Different resins and linkers were examined for an optimized peptide assembly and monitoring. The synthesized somatostatin analogues are highly resistant against enzymatic degradation as determined in vitro by incubation with rat liver homogenate. The biological activity was determined in binding experiments to the somatostatin receptors expressed in CHO‐ or BON‐1 cells. Most analogues show moderate activity without differentiation between the receptor subtypes.