MIMOSA 13

1. MIMOSA 13 Minimum Ionising particle Metal Oxyde Semi-conductor Active pixel sensor GSI Meeting, Darmstadt Sébastien HEINI 10/03/2005

2. Summary • Charge sensing element : PhotoFET. • Readout in current mode • MIMOSA 13 : a highly granular and fast sensor. • Conclusion and outlook. Sébastien HEINI 10/03/2005

3. PhotoFET : charge sensing element - 100% fill factor - N-WELL/P-epi Diode. - Liberated Charge ~80e-/µm/MIP - Collection time ~100ns • Advantages: • - Built-in charge-to-current amplification • high sensitivity • Large DC swing • High speed readout - The collected charge affects the threshold voltage of the PMOS transistor - Modulation of the transistor current signal amplification resulting in conversion of the generated charge to current Sébastien HEINI 10/03/2005

4. Optimal operation point and result of the PhotoFET • Optimal running S/N point determined by simulation. • Isf_ bias = 1µA • - Signal = 773 pA / e - • - Noise = 49 e - • - S/N = 34 Number of pixels • - 1M events analysis. • - Blue curve : neighbour pixel hit response distribution analysis • Green curve : calibration pick due to a Fe55 X ray irradiation on the central pixel • Signal / noise depend on neighbour pixel hit ADC count Sébastien HEINI 10/03/2005

5. Current mode readout • Advantages: • High speed readout. • Charge collected is amplified inside the pixel. • Low impedance is in the amplifier (outside of the array). • Pixel output simple : using a current memory. • Large DC swing. Sébastien HEINI 10/03/2005

6. Objective of MIMOSA 13 • High gain sensing element. • DC current compensation. • Noise reduction of the PhotoFET structure. • AC coupling test for lower noise contribution. • - Obtain a readout time faster than 100ns. • Direct access to the PhotoFET for caracterisation. • Test of a real fast amplifier architecture. • (readout time faster than 50ns). • - Test of the chip MIMOSA 13 in fast operation mode. • Pixel array 20 x 64 (pixel pitch 20µm). • Compatibility with datas acquisition of existing system. Sébastien HEINI 10/03/2005

7. MIMOSA 13 Topology • Technology : AMS 035. • (4 metal layer). • Substrate : low doped Hi resistivity substrate (8-10 Ω.cm). • Chip Area : 5,1mm² • Nb of pads : 44 • Pads spacing : 50µm • Gnd : 4 • Digital : 11 • Vdd : 1 • Out : 10 • Selection : 3 • Bias : 8 • Vdda pixel : 4 • Vdda ampli : 2 Sébastien HEINI 10/03/2005

8. Global view of MIMOSA 13 architecture ………………………. Column Pixels Array ........ ........ DIG. bloc row PhotoFET ………………………. memory Parallel readout Amplifier ………………… Current output Reaout line : metal wire Sébastien HEINI 10/03/2005

9. MIMOSA 13 Pixels Array (New PhotoFET) Dummi Pixel  : Mimosa 7photofet pixel to solve process continuity problems Pixel A1 10 x 16 Pixel B1 10 x 16 Pixel A1 : Mimosa7 avec Photofet pixel, new layout. Pixel A2 : Modified Photofet, source follower bandwith limitation, memory W/L=3 + cap, Photofet with W/L=3. Pixel A3 : Modified Photofet, source follower bandwith limitation, memory W/L=3 + cap, Photofet with W/L=2,2. Pixel A2 10 x 16 Pixel B2 10 x 16 Pixel A4 : Modified Photofet, source follower bandwith limitation, memory W/L=2 + cap, Photofet with W/L=2,2. Pixel B1 : Pixel with Pmos transistor and AC coupling, Current mirror reference and compensation, memoiry W/L=3 + cap. Pixel A3 10 x 16 Pixel B3 10 x 16 Pixel B2 : Pixel with Pmos transistor and AC coupling gate cap, directe reference and compensation, memoiry W/L=3 + cap. Pixel B3 : Pixel with Pmos transistor and AC coupling Nmos cap, directe reference and compensation, memoiry W/L=3 + cap. Pixel A4 10 x 16 Pixel B4 10 x 16 Pixel B4 : Pixel with Pmos transistor and AC coupling Nmos cap, High gain, directe reference and compensation, memoiry W/L=3 + cap. Matrice de Mosaic 2 : 64 rows of 20 pixels (20 x 20µm pitch). Successive row readout 10 Sorties analogique I 10 Sorties analogique I Sébastien HEINI 10/03/2005

10. MIMOSA 13 Array VDDA_SF VDDA_PHFET • 6 x 64 command lines. • Successive row readout • Write and read pattern is equal for all the pixels (A1 …B4). • 100ns for the memory writing. • 100ns for the readout of the memory SW_PWON SW_W_M1 OUT SW_W_M2 Pixel SW_R_M1 SW_R_M2 SW_R_PH BIAS_pixel GND -------- 100ns ------- -------- 100ns ------- Sébastien HEINI 10/03/2005

11. Photofet Charge sensing element SW_PWON SW_W_M1 SW_W_M2 SW_R_M1 Pixel OUT SW_R_M2 SW_R_PH Current memory 1 Current memory 2 PIXEL Pixel structure - Signal is contain in noise • Fixe Pattern Noise • Electronic noise • (thermal, 1/f, shot noise) • Signal is extract using (CDS) correlated double sampling • S1t1, S2t2 Signal = S1 - S2 Sébastien HEINI 10/03/2005

12. Amplifier and multiplexer structure 10 input analog I 10 input analog I Bias_comp Dc current Compensation bloc Sel amp Sel dir Bias A1 Bias A2 Ampli Ampli Sel 1_2 Analog multiplexer 10 output analog I Mux 2 vers 1 Classic amplifier, gain 10 Analog output Fast amplifier Sébastien HEINI 10/03/2005

13. Conclusion and outlook • Current mode maybe adapted to the high speed and high granularity requirements. • Most of the design is realized. • Submission on 25 march 2005. • Design of the test bench for MIMOSA 13. • Test and analysis of MIMOSA 13 chip. • Work over an fast ADC flash for analog signal conversion. Sébastien HEINI 10/03/2005

14. Pixel type A1, A2, A3, A4 - 6 commandes : Sw_pwon Sw_r_ph Sw_w_m1 Sw_w_m2 Sw_r_m1 Sw_r_m1 Sébastien HEINI 10/03/2005

15. Pixel type B1 - 6 commandes : Sw_r_ph Sw_w_m1 Sw_w_m2 Sw_r_m1 Sw_r_m1 Sébastien HEINI 10/03/2005

16. Pixel type B2, B3, B4 - 6 commandes : Sw_r_ph Sw_w_m1 Sw_w_m2 Sw_r_m1 Sw_r_m1 Sébastien HEINI 10/03/2005

17. Bloc d’amplification gain 10 Sébastien HEINI 10/03/2005

18. Bloc d’amplification rapide Sébastien HEINI 10/03/2005