A constant-envelope, continuous phase modulation architecture is presented in which a sigma-delta modulator is combined with an open-loop modulator. Compared to existing architectures, Σ∆ based open-loop modulation can be implemented with minimal analog circuitry. The architecture is demonstrated with a discrete implementation performing frequency modulation at a carrier frequency of 120 MHz. B...

The sigma receptor is a novel protein that mediates the modulation of ion channels by psychotropic drugs through a unique transduction mechanism depending neither on G proteins nor protein phosphorylation. The present study investigated sigma receptor signal transduction by reconstituting responses in Xenopus oocytes. Sigma receptors modulated voltage-gated K+ channels (Kv1.4 or Kv1.5) in diffe...

A self-calibrated two-point delta–sigma modulation technique for CMOS RF transmitter is proposed. This calibration technique employs voltage-controlled oscillator (VCO) and delta–sigma modulator input ports in a frequency synthesizer. By monitoring the control voltage of a loop filter, the gain mismatch between two paths can be detected and completely calibrated by modifying the gain of the VCO...

This review compares the biological and physiological function of Sigma receptors [σRs] and their potential therapeutic roles. Sigma receptors are widespread in the central nervous system and across multiple peripheral tissues. σRs consist of sigma receptor one (σ1R) and sigma receptor two (σ2R) and are expressed in numerous regions of the brain. The sigma receptor was originally proposed as a ...

Sigma delta modulation M has become a widespread method of analogue to digital conversion however its operation has not been completely de ned The majority of the analysis carried out on the circuit has been from a linear standpoint with non linear analysis hinting at hidden complexities in the modulator s operation The sigma delta modulator itself is a non linear system consisting as it does o...

While Σ∆M techniques [l, 2] are applied widely in analog conversion sub-systems, both analog-to-digital (ADC) and digital-to-analog (DAC) converters. these methods have enjoyed much less exposure in the broader application domain, where flexible and configurable solutions, traditionally supplied via a software DSP (soft-DSP), are required. And this limited level of exposure is easy to understan...

A CMOS image sensor ADC using delta-sigma modulation is presented and discussed. Experimental results from a test chip are presented. The experimental results show that the proposed ADC has several benefits over the use of pipeline ADCs including noise reduction, fast design times, ease with which to maximize ADC output based on a varying input range, and simple symmetric analog routing for lar...

The three most important factors in choosing a speech output processing method for a particular application are flexibility, bit rate and cost. Flexibility enables the user to change the binary speech patterns according to his needs; bit rate is the amount of binary information necessary to produce a certain length (I s) of continuous speech; and cost includes not only the LSl chip itself, but ...

Luminescence resonance energy transfer measurements were used to show that binding of E. coli core RNA polymerase induced major changes in interdomain distances in the sigma 70 subunit. The simplest model describing core-induced changes in sigma 70 involves a movement of the conserved region 1 by approximately 20 A and the conserved region 4.2 by approximately 15 A with respect to conserved reg...