A Novel Three-Point Modulation Technique for Fractional-N Frequency Synthesizer Applications

This paper presents a novel three-point modulation technique for fractional-N frequency synthesizer applications. Convention modulated fractional-N frequency synthesizers suffer from quantization noise, which degrades not only the phase noise performance but also the modulation quality. To solve this problem, this work proposes a three-point modulation technique, which not only cancels the quantization noise, but also markedly boosts the channel switching speed. Measurements reveal that the implemented 2.4 GHz fractional-N frequency synthesizer using three-point modulation can achieve a 2.5 Mbps GFSK data rate with an FSK error rate of only 1.4 %. The phase noise is approximately -98 dBc/Hz at a frequency offset of 100 kHz. The channel switching time is only 1.1 μs with a frequency step of 80 MHz. Comparing with conventional two-point modulation, the proposed three-point modulation greatly improves the FSK error rate, phase noise and channel switching time by about 10 %, 30 dB and 126 μs, respectively

Homeoprotein Hbx4 represses adhesion molecule governing cytokinesis and development

Homeobox genes encode proteins with a highly conserved DNA-binding motif and provoke morphological diversification of body segments by differentially controlling the expression of downstream targets. Here, we have identified _hbx4_, one of many homeobox genes in _Dictyostelium discoideum_ and investigated its role during growth and development. In suspension, Hbx4-overexpressing cells, Hbx4^OE^, showed defects in cytokinesis and growth rate. During development, Hbx4^OE^ and _hbx4_-disrupting cells, _hbx4¯_ made differences in shape of mound and slug, cell-type proportioning from wild type KAx3 cells. These phenotypes were similar to those of mutant defective in _cadA_ encoding Ca^2+^-dependent cell adhesion molecule so that we investigated the relationship between _hbx4_ and _cadA_. Overexpression of Hbx4 inhibited the expression of _cadA_ and cAMP also failed to stimulate _cadA_ in Hbx4^OE^. Furthermore, gel mobility shift assay showed the promoter of _cadA_ contained Hbx4-binding site, indicating Hbx4 negatively regulates the expression of _cadA_. Proteome analysis revealed that overexpression of Hbx4 repressed the _rdiA_ and _abpB_ encoding rho guanine nucleotide dissociation inhibitor1, RhoGDI1 and actin bundling protein 34, ABP34, respectively. And the overexpression of _cadA_ in Hbx4^OE^ cells rescued the defects and increased mRNA level of _rdiA_, _abpB_ and one of Rho GTPase, _rac1b_. These results suggested that Hbx4 can modulate cytokinesis, cell sorting and cell-type proportioning by repressing _cadA_ that regulates GTPase-dependent signaling pathway