Gain and noise distribution in a three stage amplifier system.
Two types of preamplifier system schemes. The ideal current source I represents the signal from the ICR cell. The capacitor C is the combination of the parasitic capacitance of the cell and cabling. (a) A unity gain operational amplifier with an input resistor R to convert current signal into voltage. (b) A transimpedance amplifier with a feedback resistor R.
Preamplifier circuit. (a) Schematic of the transimpedance preamplifier. (b) Single layer printed circuit board (sized ∼65 × 60 mm) with components fully populated.
Computer simulations of the preamplifier transimpedance. (a) AC analysis without the feedback capacitor C1 in Fig. 3(a). (b) AC analysis with 0.85 pF feedback capacitor.
AC analysis from the measured data. (a) Voltage gain of the main (AD8099) stage. (b) Transimpedance of the entire preamplifier system in three feedback conditions.
Measured input current noise spectral density with 18 kΩ transimpedance.
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