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We report on the recent development of a 32-channel low-noise analog front-end ASIC “KW03” for hard X-ray and gamma-ray detectors. The ASIC aims for the readout of strip or pixel (pad) detectors utilizing silicon and cadmium telluride (CdTe) as detector materials. Each readout channel includes a charge-sensitive amplifier, bandpass filters and a sample-and-hold circuit. It also includes a leakage current compensation and pole-zero cancellation circuits to meet the various detector requirements. The equivalent noise level of a typical channel reaches 89 e^- @ 0 pF (rms) and shows an input-capacitance characteristic of 7.5 e^-/pF between 0 pF and 10 pF with a power consumption of 3 mW per channel. We mounted the ASIC on a low-temperature co-fired ceramic (LTCC) package and evaluated the spectral performance by combining with a CdTe diode detector. As a result, the gamma-ray spectrum of radioactive source ^241Am was obtained with a good energy resolution of 2.23 keV (FWHM) for gamma rays of 59.5 keV at -\20~^\circC. [ABSTRACT FROM PUBLISHER]

A 4-sides buttable CdTe-ASIC hybrid module suitable for use in an X-ray flat panel detector (FPD) has been developed by applying through silicon via (TSV) technology to the readout ASIC. The ASIC has 128 × 256 channels of charge integration type readout circuitry and an area of 12.9 mm × 25.7 mm. The CdTe sensor of 1 mm thickness, having the same area and pixel of 100μm pitch, was fabricated from the Cl-doped CdTe single crystal grown by traveling heatermethod (THM). Then the CdTe pixel sensor was hybridized with the ASIC using the bump-bonding technology. The basic performance of this 4-sides buttable module was evaluated by taking X-ray images, and it was compared with that of a commercially available indirect type CsI(Tl) FPD. A prototype CdTe FPD was made by assembling 9 pieces of the 4-sides buttable modules into 3 × 3 arrays in which the neighboring modules were mounted on the interface board. The FPD covers an active area of 77 mm × 39 mm. The results showed the great potential of this 4-sides buttable module for the new real time X-ray FPD with high spatial resolution. [ABSTRACT FROM AUTHOR]

We are developing low noise analog ASICs for hard X-ray and gamma-ray astronomy. They are based on a sub-micron CMOS process. Our design includes a finely-adjustable high-resistance circuit, which, for example, enables us to realize a pole-zero- cancellation in the analog chain. A two-dimensional ASIC with a fast read-out scheme and a one-dimensional ASIC with an improved analog design are developed and verified. With the latter ASIC connected with a CdTe detector, we have obtained a radioactive source spectrum with an energy resolution of 4.6 keV(FWHM) at 59.5 keV. [ABSTRACT FROM AUTHOR]