Amplifier bandwidth

Amplifier bandwidth. The range of signal frequencies over which an amplifier is capable of undistorted or unattenuated transmission. An operational amplifier should transmit DC voltage accurately the upper (bandwidth) limit is defined as the 3-dB point (attenuation factor of two). Because bandwidth can vary with gain, the product of gain x bandwidth can be a more useful parameter. 

The Performance Analysis capabilities of Probe are used to view properties of waveforms that are not easily described. Examples are amplifier bandwidth, rise time, and overshoot. To calculate the bandwidth of a circuit, you must find the maximum gain, and then find the frequency where the gain is down by 3 dB. To calculate rise time, you must find the 10% and 90% points, and then find the time difference between the points. The Performance Analysis gives us the capability to plot these properties versus a parameter or device tolerances. Hie Performance Analysis is used in conjunction with the Parametric Sweep to see how the properties vary versus a parameter. The Performance Analysis is used in conjunction with the Monte Carlo analysis to see how the properties vary with device tolerances. In this section we will plot the bandwidth of an amplifier versus the value of the feedback resistor. See Sections 9.B.3 and 9.E to see how to use the Performance Analysis in conjunction with the Monte Carlo analysis. 

Overview of our new Ti—sapphire laser system, producing amplified bandwidth-limited ver a wide range of the visible spectrum. 

The receiver paralysis can be reduced by a better receiver design. The amplifier bandwidth must be wide enough... 

At first glance it may appear necessary to build an amplifier fast enough so that it does not broaden the detector pulses. This would require about 1 GHz for conventional PMTs and more than 3 GHz for MCPs. However, in practice the signal bandwidth is limited by the discriminators in the CFD as well. The input bandwidth of the discriminators is usually of the order of 1 GHz, so that an amplifier bandwidth above 1 to 2 GHz does not improve the timing performance noticeably. More important than extreme bandwidth are linearity and low noise, especially low noise pickup from the environment (see Sect. 7.5.4, page 311). A good preamplifier should amplify the detector pulses without noticeable nonlinearity up to the maximum CFD threshold of the TCSPC module, i.e. about 500 mV. This is no problem for the amplifiers used in the circuit shown in Fig. 7.38. 

Fio. 6. Electron photocurrent decay obtained by fitting together the current decays measured with three different amplifier bandwidths over three different overlapping time intervals. The sample was 3.8 /im thick, the applied bias was 16 V, and the temperature was 160 K. The numbers indicate the slope of the curve. [From Tiedje (1984).]... 

The purpose of the high- and low-pass filters, shown in Figure 9.2, is to eliminate interference signals such as electrode half-cell potentials and preamplifier offset potentials and to reduce the noise amplitude by the limitation of the amplifier bandwidth. Because the biosignal should not be distorted or attenuated, higher order sharp-cutting linear-phase filters have to be used. Active Bessel filters are preferred filter types because of their smooth transfer function. Separation of biosignal and interference is in most cases incomplete because of the overlap of their spectra. 

Here Av is the lesser of the laser amplifier bandwidths or that of a narrow spectral band optical filter between the laser and the detector. The first term under the square root sign is associated with the zero signal additive noise and the second arises from the beating between the signal and noise fields. Generally, the narrow field of view required to obtain a low A, and bandwidths, 5, much less than the spectral bandwidth, Av, make optical amplification... 

Nanosecond kinetic measurements need wide amplifier bandwidths which limit electronic filtering of high frequency noise. Thus noise is high. Further the statistical fluctuations in the number of photoelectrons, the so called shot noise of the PMT photocathode, is large because the number of incident photons is low in the short time intervals explored. In these conditions the S/N ratio is ... 

Fig. 38. Voltage noise of resistors as a function of the amplifier bandwidth [214]...

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