| 摘要 |
<p>An integrating transimpedance amplifier (10) comprises a differential amplifier constructed of GaAs, MESFET, HEMT, SDHT or MODFET transistors has an input coupled to the output of a radiation detector (12) and an output expressive of the detector signal integrated over a predetermined interval of time. The amplifier has a transistor (Q0) coupled to the input for coupling the input periodically to a predetermined voltage potential and a transistor (Q9) coupled to the output of the amplifier for simultaneously periodically coupling the output to a predetermined voltage reference, thereby initializing the amplifier at the beginning of an integration period. A buffer transistor (Q4) couples the output of the amplifier to a GaAs MISFET switch (Q8) which is periodically activated to couple the buffered amplifier output to a storage capacitor (Csmp). The buffer transistor also couples the output of the amplifier to a feedback capacitor (Cf) which is connected between the output of the buffer amplifier and the input of the amplifier for minimizing an effect associated with the radiation detector parasitic capacitance. The magnitude of the buffered amplifier output is stored on the capacitor at the beginning and end of the integration period. The sample signal is read out by a multiplexer twice during the integration period, the difference between the initial and final value of the buffer amplifier output being indicative of the radiation impinging on the detector minus one or more noise components.</p> |
