An analysis and optimization of an oscillator based detection chain, dedicated to the conditioning of low input signals, is presented in this paper. The concept is based on an indirect detection of the current generated at the input of the detection chain, through a Voltage Controlled Oscillator (VCO) response. In order to improve the correlation between the input current and the oscillator response (signal recognition), the full characterization of the VCO is presented. The solution enhances the particle recognition with a simple analysis of the VCO output. The new output parameter variations are analyzed and the system resolution is explored.