chapter  10
54 Pages

- Data Converters

Analog Converters (DAC), Analog to Digital Converters (ADC) and Time to Digital

Converters (TDC). Digital to Analog Converters are primarily used for slow control

functions, such as setting bias currents and voltages or discriminator thresholds. The

required resolution is in most cases from a few bits to 7-8 bits and the operation speed

is typically modest. Their design does not pose specific challenges and it is therefore

not discussed in detail here. The reader is referred to standard microelectronics text-

books for the topic. The design of ADC and TDC presents instead peculiar features.

The required resolution is often moderate (less than 10 bits), but the large number

of converters that must be accommodated on chip and the low power consumption

allowed for their operation are rarely found in other applications. Therefore, these

components deserve a specific treatment. In the first part of the chapter, we review the

key ADC performancemetrics, emphasizing the aspects that are more relevant for the

readout of radiation sensors. Since ADCs are extremely common components, many

different architectures have been reported in the literature. In the second section, we

focus our attention on two of the most useful topologies for radiation sensor front-

ends, namely the Wilkinson and the the Successive Approximation Register (SAR).

Descriptions of other ADC architectures can be found in specialized books, such

as [1-4]. The second part of the chapter is devoted to TDCs. Also for this building

block a lot of different variants exist. An exhaustive review is available in [5]. Here,

after a general introduction, we describe a few schemes which are of greater interest

to the field of radiation detection.