I am incrementally updating the XR Data Sheet. I’ll post updates here every once in a while. Here’s the schematic of the XR preamplifier. The circuit utilises the Toshiba 2SC3324 low noise NPN transistors with an exceptional noise figure of 0.2dB (typical). The preamp configuration is a common emitter amplifier with both emitter feedback and self-biasing collector feedback. The collector feedback ensures that the transistor is always biased in the active region regardless of variations in Beta. The second stage is a simple emitter follower providing current gain and low output impedance.
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