scholarly journals Design of a Switched Capacitor Negative Feedback Circuit for a Very Low Level DC Current Amplifier

2013 ◽  
Vol 04 (04) ◽  
pp. 356-363
Author(s):  
Hiroki Higa ◽  
Naoki Nakamura
2005 ◽  
Vol 44 (5A) ◽  
pp. 3287-3292
Author(s):  
Hiroki Higa ◽  
Takashi Higashionna ◽  
Takehiro Maehama ◽  
Ikuo Nakamura

Author(s):  
Guangbao Zhang ◽  
Shuting Hu ◽  
Xiaoqiang Jia

Although many whole-cell biosensors (WCBs) for the detection of Cd2+ have been developed over the years, most lack sensitivity and specificity. In this paper, we developed a Cd2+ WCB with a negative feedback amplifier in P. putida KT2440. Based on the slope of the linear detection curve as a measure of sensitivity, WCB with negative feedback amplifier greatly increased the output signal of the reporter mCherry, resulting in 33% greater sensitivity than in an equivalent WCB without the negative feedback circuit. Moreover, WCB with negative feedback amplifier exhibited increased Cd2+ tolerance and a lower detection limit of 0.1 nM, a remarkable 400-fold improvement compared to the WCB without the negative feedback circuit, which is significantly below the World Health Organization standard of 27 nM (0.003 mg/L) for cadmium in drinking water. Due to the superior amplification of the output signal, WCB with negative feedback amplifier can provide a detectable signal in a much shorter time, and a fast response is highly preferable for real field applications. In addition, the WCB with negative feedback amplifier showed an unusually high specificity for Cd2+ compared to other metal ions, giving signals with other metals that were between 17.6 and 41.4 times weaker than with Cd2+. In summary, the negative feedback amplifier WCB designed in this work meets the requirements of Cd2+ detection with very high sensitivity and specificity, which also demonstrates that genetic negative feedback amplifiers are excellent tools for improving the performance of WCBs.


Telecom IT ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 9-14
Author(s):  
Y. Nikitin ◽  
G. Tsygankov

A model of a pulse phase-locked loop multiplying ring in a MicroCap11 medium is considered. The analysis uses a nonlinear model of a voltage-controlled oscillator with a user-defined control characteristic. An RS-trigger is used as a pulse-phase detector, a pulse counter in the negative feedback circuit is implemented on JK-triggers. Transient processes in the ring, as well as the spectrum of the output oscillations in the steady (stationary) mode are considered.


Sign in / Sign up

Export Citation Format

Share Document