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Preamplifiers and Switchers

Preamplifiers

The electrical current from photodiode array is integrated in read out CMOS chip by charge amplifiers (one for each pixel). The voltage output from charge amplifier is sampled at the same time for all pixels. The sampled voltage value is then read out in serial mode. Readout is controlled by internal shift register of CMOS chip.

The following preamplifiers are currently available:

Channels: 64 or 128
Gain: 0.5 pF~3.5 pF
Integration time: 100 us~150 ms
Readout rate: 20 kHz~1 MHz
Dynamic range: 2389~12768 @ Cpd < 33 pF

Channels: 32
Gain: 0.5 pF~25.5 pF
Output driver selection (new)
Video output enable (new)
Integration time: 100 us~150 ms
Readout rate: 20 kHz~1 MHz
Dynamic range: 2063~31703 @ Cpd < 55pF

Preamplifiers can be customized according to customer needs

Switchers

Switcher is a multi-channel ASIC chip which is used in CT machines. Switcher connects the detector diodes to the preamplifier inputs, and has several modes to meet certain electrical requirements. It is composed mainly with 3-8 decoder, NMOS switchers and ESD circuits. Input pads connected with the Photodiode array, and output pads connected to the input of external preamplifiers. A finished module consists of two static Switcher chips connected to either side of the PD Array chip.

The switchers are always customized for customer applications

Features:

- Low power consumption
- Low leakage current
- Low thermal drift
- High reliability