This paper describes selectivity and sensitivity performance evaluations and improvement methods for an on-off keying super-regenerative (SR) receiver. A slope-controlled quasi-exponential quench waveform, generated by a low-complexity PVT-tolerant quench generator circuit, is proposed to increase data rate and reduce the receiver 3-dB bandwidth, thereby preventing oscillation caused by out-of-band injected signals and improving the receiver selectivity. The SR receiver sensitivity is also enhanced by a noise-canceling front-end topology with single-ended to differential (S2D) signal converter. To exemplify these techniques, we designed an SR receiver with the proposed front-end and quench waveform generator in a 0.18-μm CMOS technology. Theoretical analyses and circuit simulations show 30% and 65% reduction in 3-dB bandwidth of the SR receiver at 25 Mbps data rate by employing the proposed quench signal compared with piecewise-linear and trapezoidal quench waveforms, respectively. Performance of the proposed front-end is evaluated by a fast bit-error-rate estimation procedure, based on circuit noise simulations and statistical analyses, without the need for time-consuming transient-noise simulations. Accuracy of the procedure has been verified by comparing its results with transient-noise simulations. According to the estimated bit-error-rate curves, the noise-canceling topology with S2D converter enhances the SR receiver sensitivity by 9 dB.The noise-canceling RF front-end with S2D conversion is shown in Figure 7. A common gate (CG)common source (CS) LNA topology is employed to provide input impedance matching and S2D conversion. Trans-conductance of the CG transistor, M 3 , is set to 20 mS for 50-Ω input impedance matching. The biasing circuit in Figure 2 is also employed in the LNA to reduce the effect of PVT variations on trans-conductance of M 3 and M 4 . Phase difference between the two signals injected by the CS transistor, M 4 , and the CG transistor, M 3 , to the SR oscillator core is about 180 degrees. The Figure 6. (a) The conductance curve, G(t); (b) the sensitivity pulse, s(t), and the normalized oscillation envelope, p(t); and (c) the super-regenerative band-pass function, |H bp (ω)|, of the proposed quench technique for three different values of G À and gain. Data rate is 25 Mbps in all cases.Figure 8. The super-regenerative oscillator output employing (a) the proposed S2D converter and (b) a single-ended LNA. (c) Histogram of the oscillator output low level, derived from Monte Carlo simulations.Figure 14. Transient-noise simulation of the super-regenerative receiver at 25 Mbps data rate: (a) the input pulse, (b) oscillator differential output, (c) envelope detector output, and (d) output signals of the comparator and the flip-flop.

In this paper, we showed that gravity might have been repulsive in the first moments of the Universe! To find this, we used quantization of the anti-commuting space and derived a gravitational equation in the limit T ≫ Tp, which shows interesting behaviors. We saw that gravity is repulsive in the distances less than R = 4.37 × 10 −32 × √ M , where M is the mass of the object which gives rise to the gravitational field. Also, we calculated an acceleration of the order ≃ −3.494 × 10 52 for the first moment of the Universe (r = 0), where the temperature is T ≫ Tp. Our results can explain the inflation in the first stages of the Universe and do not have any singularity at r = 0.

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Abstract:Effects of an extra PdO layer in resistance-based hydrogen sensors are considered. P-type Si substrates were subjected to porous Si by electrochemical etching at room temperature. One category of samples has PdO layer in its structure while the other one does not. We have used electron-beam method for Pd deposition. Results show that when electron-beam technique is used for Pd deposition, existence of PdO layer will increase the range of sensors' operation up to 1% of hydrogen concentration. These samples will be saturated after 186sec-onds, while the samples without this layer can detect hydrogen up to 0.6% in 150 seconds response time.