improved handling.} Cables as well as connectors will be bought by GSI and are available in
Frankfurt.
-Table \ref{iocount} gives a rough count of necessary I/O. The final number of connections required
-will strongly depend on the realization of the converter board, mainly with respect to the data
-buses for switches and ADCs. A.t.m. there are 14 I/O per converter board plus 15 I/O per sensor.
-Note that this setup is for M26 sensors only where we will not have any ladders larger than 2
-sensors. The number of I/O for the final sensor will be different.
-
+Table \ref{iocount} gives a rough count of necessary I/O.
Not all signals need a direct connection to the FPGA. To reduce the number of lines, all ADC, DAC
and switches are operated by a microcontroller on the CB. Communication with the FPGA is
implemented as SPI or UART.
+The final number of connections required
+will strongly depend on the realization of the converter board, mainly with respect to the data
+buses for switches and ADCs. A.t.m. there are 14 I/O per converter board plus 10 I/O per sensor.
+Note that this setup is for M26 sensors only where we will not have any ladders larger than 2
+sensors. The number of I/O for the final sensor will be different.
+
\begin{table}[hbtp]
\centering
\begin{tabularx}{\textwidth}{X|c|c|c|c}
\section{Converter Board (CB)}
\subsection{General Setup}
The converter boards handles all signals for the sensors: data, JTAG, control, voltages.
-\final{One final converter board serves one ladder (whatever that means, e.g. 5)
-sensors}. For the current setup, one converter board handles two
+\final{One final converter board serves one ladder (whatever that means, e.g. 5
+sensors)}. For the current setup, one converter board handles two
sensors.
The design of the converter board should be in a way to easily change the number of sensors,
i.e. all electronics should be modular, either independent for each sensor - or shared between all
of them.
\subsection{Voltage and Current Monitoring}
-All voltages and currents should be monitored. These are three supply voltages and currents per
-sensor (i.e. analog and digital VDD as well as the clamping voltage), the 8 internally generated
-bias voltages, the temperature and ground sense.
+All voltages and currents should be monitored. These are the two supply voltages and currents per
+sensor (i.e. analog and digital VDD), the 8 internally generated bias voltages, the temperature and ground sense.
The signal of the temperature diode can only be measured using a sense line for the actual ground
level on the sensor with a dedicated sense wire. This is provided by the ADC.
The 8 VDiscr signals must be analyzed both single ended and differential\footnote{The voltages
are labeled 1A-1D and 2A-2D. We need both the absolute value of the voltages '2' ($\approx$2V) as
well as the differences between 1A-2A, 1B-2B etc. These are in the order of $\pm$ 32 mV.}.
-A instrumentation amplifier provides the differential amplification. Combined with an analog
+A instrumentation amplifier provides the differential amplification. Combined with two analog
multiplexer, only two ADC channels are required for this.
In total, 8 ADC channels are needed per sensor. The on-board ADC should provide about 200 kSPS,
All voltages are switchable from FPGA. The JTAG chain and sensor clock need the option to disable
individual sensors, totaling in four signals per sensor.
-For clamping voltages and current monitoring thresholds 4 configurable voltages are necessary per
+For clamping voltages and current monitoring thresholds 3 configurable voltages are necessary per
sensor. The clamping can be provided by the previous method where it can be changed with a
-potentiometer only. The threshold voltages for current monitoring must be configurable at run-time
-with a slow but precise DAC. LTC2600 has already been used in many of our designs, is easy to
-control and chainable.
-
-
+potentiometer only. An option to use a DAC-generated voltage is foeseen. The threshold voltages for
+current monitoring must be configurable at run-time with a slow but precise DAC. LTC2600 has
+already been used in many of our designs, is easy to control and chainable - the lower precision
+LTC2620 is also sufficient.
+\subsection{Switching}
+Several switches are available to control the signals for each sensor individually:
+\begin{itemize*}
+\item Clock, Start, Reset
+\item all JTAG signals, including source of the TDI for the following sensor
+\item voltage regulator
+\item voltage switch FETs
+\end{itemize*}
\subsection{Connectivity}
All communication to the TRB3 should be differential. Test pads for most signals should be added to
-connect external, more precise instruments.
+connect external, more precise instruments (in case no vias or component pads are available for easy probing.
All signals from and to the sensor should be fed through LVDS buffers to reduce the load on the
sensors' output drivers and to improve signal quality.
are buffered by an OpAmp before sent to the Front-end board where additional methods are foreseen
for testing purposes.
+The supply for the board itself is also divided in analog and digital power. All regulators can be
+ADP125, despite on the board digital supply. Here, the total current approaches 500 mA, so taht a
+LTC1965 should be used.
+
\subsection{Micro-controller}
ADC, DAC and Switches are controlled by a STM32F103RC micro-controller.
\begin{table}[htb]
\centering
-\begin{tabular}{l|c|c|c|c}
- & \multicolumn{2}{c|}{\textbf{per Sensor}} & \multicolumn{2}{c}{\textbf{per
-FEB}} \\
-\textbf{Purpose} & \textbf{Single} & \textbf{Differ.} & \textbf{Single} & \textbf{Differ.}\\
+\begin{tabular}{l|c|c}
+ & \multicolumn{2}{c|}{\textbf{per Sensor}} \\
+\textbf{Purpose} & \textbf{Single} & \textbf{Differ.}\\
\hline
-Sensor Data & - & 4 & - & -\\
-Sensor Control & - & 1 & 2 & - \\
-JTAG & 2 & - & 2 & - \\
-Temperature & 1 & - & - & - \\
-Analog VCC & \discuss{2} & - & - & - \\
-Analog GND & \discuss{5} & - & - & - \\
-Clamping VCC & 1 & - & - & - \\
-Digital VCC & \discuss{1} & - & - & - \\
-Digital GND & \discuss{2} & - & - & - \\
-Sense VCC & 2 & - & - & - \\
-Sense GND & 1 & - & - & - \\
-Sense VDiscr & 8 & - & - & - \\
+Sensor Data & - & 4 \\
+Sensor Control & 2 & 1 \\
+JTAG & 4 & - \\
+Temperature & 1 & - \\
+Analog VCC & 3 & - \\
+Analog GND & 5 & - \\
+Clamping VCC & 1 & - \\
+Digital VCC & 3 & - \\
+Digital GND & 10 & - \\
+Sense VCC & 2 & - \\
+Sense GND & 1 & - \\
+Sense VDiscr & 8 & - \\
\hline
-Total & 25 & 5 & 4 & 1 \\
+Total & 40 & 5 \\
\end{tabular}
\caption{Connections between CB and FEB.}
\label{CbFebCable}
\subsection{Monitoring}
All reference voltages from the sensors should be forwarded to the converter board. The critical
signals like clamping and bias voltages can be decoupled from the sensor either by 0R resistors (to
-remove the connection when needed) or via impedance converters. This is possible since this version
-of front-end does not need to stand high radiation doses, the feature might be unnecessary on the
-final board and there is no harm if such a circuit fails.
+remove the connection when needed).
jspc29 / mvd_docu.git / commitdiff