A. Dorokhov, IPHC, Strasbourg, France 1 Description of pixel designs in Mimosa22 Andrei Dorokhov Institut Pluridisciplinaire Hubert Curien (IPHC) Strasbourg, France 03/04/2008 address:

A. Dorokhov, IPHC, Strasbourg, France 2 Pixel designs  Standard and Radiation tolerant nwell diode designs  Different schematic concepts: 1.Reset diode and standard amplifier (like in Mimosa8) 2.Reset diode and amplifier with improved load 3.Continuously biased (self-biased) from feedback and amplifier with improved load (like in Mimisa15 test structures and Mimosa16) 4.Reset diode from feedback, time variant feedback, amplifier with improved load (similar to Mimosa1819 test structures) 5.Reset diode from feedback, time variant feedback, standard amplifier  CDS with clamping capacitance

A. Dorokhov, IPHC, Strasbourg, France 3 Nwell diode designs  Size from 3.4 um x 3.4 um - to 4.5 um x 4.5 um  Standard with thick oxide around Nwell  Radiation tolerant with thin gate oxide around Nwell

A. Dorokhov, IPHC, Strasbourg, France 4 Amplifier schematics (1): standard common source + reset in out bias signal current M2 M3 Id M1 reset Nwell / Pepi

A. Dorokhov, IPHC, Strasbourg, France 5 Amplifier schematics (2): improved common source + reset in out bias signal current M2 M3 Id M1 reset Nwell / Pepi M4

A. Dorokhov, IPHC, Strasbourg, France 6 Amplifier schematics (3): improved common source + continuously biased from feedback (self-biased) out signal current Nwell / Pepi Pdiff / Nwell in out M2 M3 Id M4 M5 Low-pass filter feedback

A. Dorokhov, IPHC, Strasbourg, France 7 Amplifier schematics (4): improved common source + reset from feedback (time-variant feedback) signal current Nwell / Pepi in out M2 M3 Id M4 M5 Time-variant feedback reset

A. Dorokhov, IPHC, Strasbourg, France 8 Amplifier schematics (5): standard common source + reset from feedback (time-variant feedback) signal current Nwell / Pepi in out M2 M3 Id M4 Time-variant feedback reset

A. Dorokhov, IPHC, Strasbourg, France 9 Summary of pixel concepts  (1,2) reset (and amplifier bias) from constant voltage  - may be difficult to find working point due to CMOS process variation  - diode leakage current dispersion after irradiation may significantly degrade performance  (3) self-biased from feedback  + performances should be more stable to process variation  + diode leakage is compensated by forwardly biased diode  - “pedestal memory effect” from previous hit, even removed after CDS, changing the performance of amplifier  (4,5) reset from feedback  + more stable performances for process variation  - diode leakage current dispersion after irradiation will significantly degrade performance

A. Dorokhov, IPHC, Strasbourg, France 10 Simulation results Simulation with Spectre, parasitic capacitances for diodes, metal lines and transistors are extracted by Frédéric Morel

A. Dorokhov, IPHC, Strasbourg, France 11 Measurement results 1. Short results summary of measurements and analysis from Mathieu Goffe: 1.S6, S7, S8, S9, S10, S12, S13, S15, S16, S17 are working fine at standard conditions at 100MHz clock 2.For working pixels the charge collection in seed ~30%, cluster 3x3: 60-80%, in cluster 5x5 : 80-90%, noise from 10e to 13e 3.The other pixels have to be investigated further – one need to vary the frequency, readout pattern, analogue voltages – at least to understand the reason why they don’t show good performances seen in simulations (this is foreseen for the end of April) 2.However, there are at least few working amplifier concepts:1,2,3. 3.Two designs S6 and S10 have different concepts: reset and self- biased from feedback, they are featured with radiation tolerant version of nwell diode -> one can have close look at their performances

A. Dorokhov, IPHC, Strasbourg, France 12 Measurement results for S6 and S10

A. Dorokhov, IPHC, Strasbourg, France 13 Measurement results for S6 and S10 S6, pedestal dispersion + noise S10, pedestal dispersion + noise

A. Dorokhov, IPHC, Strasbourg, France 14 Measurement results for S6 and S10 S6, pedestal mean dispersion S10, pedestal mean dispersion

A. Dorokhov, IPHC, Strasbourg, France 15 Measurement results for S6 and S10 S6, pedestal sigma dispersion S10, pedestal sigma dispersion

A. Dorokhov, IPHC, Strasbourg, France 16 Influence of pixel hit frequency 1. Designs with reset are not sensitive to “memory” effect – charge is always restored to a fixed value 2. Continuously biased diode will store some fraction of charge from previously incident particle, even if the signal completely reconstructed after CDS, there is “internal memory” in the nwell diode -> charge is accumulated and circuit can go to non-linear state

A. Dorokhov, IPHC, Strasbourg, France 17 Influence of pixel hit frequency: simulation 1. Single pixel hit frequency 2Hz for 30um x 30um pitch 2. Noise – Gaus : SIGMA=15 e 3.Signal - Landau distribution: MPV=200e, SIGMA=50e 4.Initial nwell diode voltage 0.7 V 5.Amplifier gain -10, offset 1.1 V 6.Frame readout (integration time) time 160 us (==1000 pixels in column, 100MHz clock)

A. Dorokhov, IPHC, Strasbourg, France 18 Influence of pixel hit frequency

A. Dorokhov, IPHC, Strasbourg, France 19 Influence of pixel hit frequency

A. Dorokhov, IPHC, Strasbourg, France 20 Influence of pixel hit frequency

A. Dorokhov, IPHC, Strasbourg, France 21 Influence of pixel hit frequency

A. Dorokhov, IPHC, Strasbourg, France 22 Influence of pixel hit frequency

A. Dorokhov, IPHC, Strasbourg, France 23 Influence of pixel hit frequency

A. Dorokhov, IPHC, Strasbourg, France 24 Influence of pixel hit frequency

A. Dorokhov, IPHC, Strasbourg, France 25 Influence of pixel hit frequency

A. Dorokhov, IPHC, Strasbourg, France 26 Influence of pixel hit frequency

A. Dorokhov, IPHC, Strasbourg, France 27 Conclusions 1.There two pixel candidates for PHASE1: designs S6 and S10 2.Radiation hardness and hit frequency issues has to be carefully studied for these candidates – one of those may be not suitable for real experiment…