Electronic Readout

The silicon vertex detector discu.ssed liere places aljout 5 X 10 readout channels in a very limited space imposing severe restrictions on the volume occupied by the readout electronics, cables and connectors, and on the j)ower consumption. The specifications for the readout system include the following  

The readout chip will be a VLSI circuit consisting of a front-end amplifier, followed by a comparator, analog or digital storage, and a readout section. To minimize material and connections, the readout circuitry should be accomodated on a single IC. 

We have compared radiation hard CMOS (1.2 fim feature size fabricated by UTMC) and bipolar integrated circuitr (Tektronix, but AT T or Westinghouse yield similar results) to determine the best technology for this application. Fig. 2.14 shows the calculated noise performance vs. shaping time for a detector capacitance of 22 pF. At short shaping times the shot noise contribution of the bipolar transistor s base current becomes small 

The noise characteristics of radiation hard CMOS at ionizing doses up to 5 Mrad have been measured by a UCSC/LBL collaboration [12]. Although deterioration of noise is observed, circuitry can be designed to maintain the required noise levels in this detector with substantial safety margins. 

Details of the front-end circuitry depend strongly on the design of the detector readout, as the added capacitance of the second layer metal and the resistance of the readout lines and strip electrodes substantially affect the noise characteristics. Minimizing these additional contributions is an important part of the front-end design. Utilization of a separate kapton laminate for the second layer z-readout should reduce both capacitance and cost. 

---

Sensors for Measuring % RH. Over the years, devices other than the simple hair hygrometer have evolved which permit a direct measurement of i RH. These devices are. Inr the most part, electrochemical sensors that offer a degree of ruggedness, compactness, and remote electronic readout ability not afforded hy hair devices. 

The principles underlying the operation of the chromatograph and its use in a commercial separation process are discussed in Volume 2, Chapter 19. In this section emphasis is placed on its function as an on-line process analyser in which form it consists of three major subdivisions (apart from any electronic readout system), viz. the sampling assembly, the chromatograph column and the detector. All three are generally contained within the same temperature-controlled environment (Fig. 6.50). 

Readout Noise. As defined in Section 4.2.5, readout noise is the standard deviation of sequential measurements of a constant number of electrons. Readout noise is generally determined by successive readouts of a dark detector with very short integration time. 

Spectrometer An instrument equipped with a monochromator or a polychromator, a photodetector, and an electronic readout that displays a number proportional to the intensity of an isolated spectral band. 

Ewing (57) has reviewed electronic laboratory balances. The various types of null detectors, such as optical, inductive, and capacitance types, as well as the electronic readouts are discussed. 

J.S. Milnes, M. Page, M. Ingle, J. Howorth, Improved electronic readout system for an imaging photon detector, Nucl. Inst, and Meth. A 513, 163-166 (2003)... 

The JFET switch Is closed by the step application of a -5 volt signal. Whenever this voltage step Is applied to the open switch, the Inherent junction capacitance of the JFET causes charge to be Injected Into the readout circuit. The fluctuation In this charge generates an electronic readout or scanning noise current (n ), which Is Independent of the photodiode signal current 1. ... 

The relatively low throughput of reverse optic/polychroma tor designs utilized In photodiode array UV absorbance detectors and an electronic readout noise Incurred In scanning an array currently limit noise In this detector to approximately 5x10 au. 

However, photodiode readout is inferior in terms of the low energy detection threshold which can be achieved. This is due to the lack of internal gain within the photodiode, which means that electronic readout noise will dominate the detector performance at low energies. A typical threshold for a Icc CsI(Tl) detector will be in the range 30-50 keV. At energies below 50 keV a bare silicon photodiode becomes a useful X-ray detector due to photoelectric absorption within the bulk of the silicon. 

The advantage of this method, compared to the rim-and-face procedure, is its higher precision, reliabiUty and speed through the electronic readout There is no sag problem, and it can be used for larger measurement distances. 

The detector module in FllnS has been tailored to LeKIDs detectors, which are still under development. To this date, very little is known on the noise properties and non-linearities of these detectors where substantial research is taking place. With publication of such results, appropriate modification of the detector module can take place. Also, an extension to a detector array simulation is planned, as well as the inclusion of the electronics readout. Due to the modular design of FllnS, other detector technologies can also be simulated. 

Electrochemical techniques offer attractive approaches to the detection and identification of nucleic acids, a central activity of modern chemical biology [520]. High sensitivity, low costs of instrumentation, a ready capacity for miniaturization, and direct electronic readout offer strong motivations for the development of this field [520]. Recently, there has been a growing tendency toward the development of this technology. 

These reagentless and reusable sensors work on the principle that the chemical interaction (hybridization) between DNA targets (in solution) and the probe layer (attached to an electrode) produces signal currents for electronic readout (Fig. 12.1). 

The basic principle and the electronic readout diagram is shown in Fig. 4.91. An external bias voltage Uo is applied to p-n diodes with the sensitive area A and the internal capacitance Cs. Under illumination with an intensity / the photocurrent /ph = rjAI, which is superimposed on the dark current /q, discharges the diode capacitance Cs during the illumination time AT by... 

Thicknesses of films of the polymers were determined by two methods 1) mechanically, using a high precision micrometer with electronic readout and 2) by measuring film capacitonce C on a multifrequency LCR meter. The required dielectric constant was itself calculated by an iterative procedure from an average of multiple measurements of capacitance on free standing films whose thickness had been determined mechanically. 

Azmi et al. (2014) created a handheld, POC system, in which a silicon nanowire biosensor (SiNW) chip is wire-bonded to a bio-smartcard and subsequently slotted into an electronic readout device. This sensor detects an oxidative stress biomarker, 8-hydroxydeoxyguanosine (8-OHdG), which has been related to prostate cancer risk. 

---