CCPD prototype chips

Photograph of the HVPixel2 chip.

The mechanical structure of the CCPD.

Photograph of the CCPD detector during wire-bonding.

Efficiency of the CCPD matrix - detection of the signals above 948e is possible.

HVPixel2

HVPixel2 is the multi-purpose test-chip with monolithic- and CCPD-structures. (CCPD - capacitively coupled hybrid-pixel detector.) HVPixel2 is implemented in 350nm AMS HV-technology. The chip contains one monolithic pixel matrix and one sensor-matrix for a CCPD, both implemented as the smart diode arrays. Additionally, the chip contains a matrix of the readout-cells that are used for the CCPD-sensor readout. The CCPD pixels contain charge sensitive amplifiers. The CCPD readout cells contain a receiver, a discriminator with a threshold tune circuit and a digital part with the window logic. All the CCPD circuits are implemented using radiation tolerant layout.

Results

The first test-beam measurement has been performed with the monolithic pixel matrix. The minimum ionizing particle (MIP) signal-spectrum has been measured. The single pixel signal is 1800e (most probable value - MPV).

The detection parameters such as the signal-to-noise ratio (SNR), the threshold dispersion, the detection efficiency have been measured on the matrix level. The measured SNR for MIPs is 30.

The first functional CCPD detector has been built. The CCPD detector consists of two HVPixel2 chips glued onto each other. The detection parameters have been measured. Radiation tolerance of at least 50MRad has been demonstrated by irradiating the chip with x-rays.

Photographs of the CAPSENSE and CAPPIX chips.

Photograph of the CCPD based on CAPSENSE/PIX.

3D layout of the CAPPIX readout cell made with the Gds2Pov software.

Efficiency of the CCPD matrix based on CAPSENSE/PIX. The detection of the signals above 300e is possible.

CAPSENSE radiation tolerance - after irradiation with protons to 10¹⁵ n_eq/cm₂, a SNR of 53 has been measured for the high energy beta-particles, even at +10C.

CAPSENSE and CAPPIX

CAPSENSE and CAPPIX are the sensor- and the readout-chip for a CCPD detector. The pixel readout chip - CAPPIX (180nm UMC CMOS technology) is mounted on the SDA sensor CAPSENSE (350nm AMS HV technology - 50x50 micrometer pixels). Only CAPSENSE needs to be wire-bonded. The chip provides power and the signals for the CAPPIX through a few bump-bonds. The sensor signals are transmitted capacitively. Using of the bump bonds for power and the IO signals assures scalability of the concept - the readout of big sensors with a large number of small readout chips is possible. We have implemented optionally the inductive power supply for CAPPIX. If it works, CAPPIX will operate without any single IO pad.

The CAPSENSE pixels contain the charge sensitive amplifiers. The CAPPIX readout cells contain a receiver, a discriminator with a threshold tune circuit and a digital part with the window logic. We have NOT used the radiation tolerant design.

Results

Excellent signal-to-noise ratio has been measured. The measured single pixel SNR is up to 60 and the noise as low as 23e. The detection parameters have been measured for the whole matrix as well. The minimal detectable signal for a negligible noise occupancy is 300e.

The sensor CPASENSE can be also tested stand-alone. We have performed several irradiations of the chip to test the radiation tolerance. After irradiation with protons to 10¹⁵ n_eq/cm₂, a good signal-to-noise ratio has been measured for the high energy beta-particles, even at nearly room temperatures (+10C).