Improvement of a highly sensitive and specific whole-cell biosensor by adding a positive feedback amplifier

In this study,we designed a Cd^(2+)whole-cell biosensor with both positive and negative feedback cascade am-plifiers in Pseudomonas putida KT2440(LTCM)based on our previous design with only a negative feedback amplifier(TCM).The results showed that the newly developed biosensor LTCM was greatly improved compared to TCM.Firstly,the linear response range of LTCM was expanded while the maximum linear response range was raised from 0.05 to 0.1μM.Meanwhile,adding a positive feedback amplifier further increased the fluorescence output signal of LTCM 1.11–2.64 times under the same culture conditions.Moreover,the response time of LTCM for detection of practical samples was reduced from 6 to 4 h.At the same time,LTCM still retained very high sensitivity and specificity,while its lowest detection limit was 0.1 nM Cd^(2+)and the specificity was 23.29(compared to 0.1 nM and 17.55 in TCM,respectively).In summary,the positive and negative feedback cascade amplifiers effectively improved the performance of the biosensor LTCM,resulting in a greater linear response range,higher output signal intensity,and shorter response time than TCM while retaining comparable sensitivity and specificity,indicating better potential for practical applications.

CFOA Based Band Pass and Band Stop Ladder Filter—A New Configuration

A new technique for the conversion of ladder based filter into CFOA based filter has been proposed. The technique uses signal flow graph and converts the existing LC ladder based filter into band pass & band stop configurations. The design of band pass and band stop filter has been realized using the proposed technique. The proposed configuration is implemented using CFOA as an active device and all the capacitors are grounded. CFOA based circuits have greater linearity, high dynamic rate, high slew rate and high signal bandwidth. Simulation has been carried out using simulation software P Spice (v10.1). The simulation results have been demonstrated and discussed.

Modulated bandwidth enhancement in an amplified feedback laser

We report a direct, modulated bandwidth enhancement in a amplified feedback laser （AFL）, both experimen- tally and numerically. By means of fabricated devices, an enhanced -3 dB bandwidth of 27 GHz with an in-band flatness of ±3 dB is experimentally confirmed at 13℃. It is numerically confirmed that the modulated bandwidth of the AFL can be enhanced to two times its original bandwidth, with more controlled flexibility to realize a flat, small-signal response.

Simulation and experimental characterization of a dual-mode two-section amplified feedback laser with mode separation over 100 GHz

A tunable two-section amplified feedback laser, which employs an amplifier section as the integrated feedback cavity, is designed and fabricated for dual-mode operation with mode separation of 100 GHz. Detailed simulations and experimental characterizations on the performance of the laser are presented. Promising dual-mode emission with continuous tuning range over 16 GHz（87.41–103.64 GHz） is experimentally demonstrated.

A 0.02% THD and 80 dB PSRR filterless class D amplifier with direct lithium battery hookup in mobile application

This paper presents a fully integrated CMOS filterless class D amplifier that can directly hook up lithium battery in mobile application The proposed amplifier embodies a 2-order feedback path architecture instead of direct feedback of output to input of the integrator to decrease the high frequency intermodulation distortion associated with direct feedback and eliminate the integrator input common mode disturbance from the output in ternary modulation. The prototype class D amplifier realized in 0.35 μm digital technology achieves a THD＋N of 0.02% when delivering 400 m W to an 8 Ω load from V_（DD） =3.6 V. The PSRR of the prototype class D amplifier is 80 dB at217 Hz. Furthermore a filterless method that can eliminate the external LC filter is employed which offers great advantages of saving PCB space and lowering system cost. In addition the prototype class D amplifier can operate in large voltage range with V_（DD）range from 2.5 to 4.2V in mobile application. The total area of the amplifier is 1.7mm^2.

A low noise CMOS RF front-end for UWB 6-9 GHz applications

An integrated fully differential ultra-wideband CMOS RF front-end for 6-9 GHz is presented.A resistive feedback low noise amplifier and a gain controllable IQ merged folded quadrature mixer are integrated as the RF front-end. The ESD protected chip is fabricated in a TSMC 0.13μm RF CMOS process and achieves a maximum voltage gain of 23-26 dB and a minimum voltage gain of 16-19 dB,an averaged total noise figure of 3.3-4.6 dB while operating in the high gain mode and an in-band IIP3 of-12.6 dBm while in the low gain mode.This RF front-end consumes 17 mA from a 1.2 V supply voltage.