Performances of front-end electronics based on sigma-delta modulation — A simulation study

We present a novel front-end electronic design using sigma-delta (Σ-Δ) modulation. The new design needs only one analog amplifier, one differential digital input port and one digital output port from a FPGA. Both the energy and timing calculation are implemented in FPGA firmware. A Simulink model is established to simulate and evaluate the circuit design and the sample data processing. The energy is calculated directly by summing the sequences of 0 and 1 generated by the 1-bit Σ-Δ ADC module. The simulation disclosed the non-linear transfer function of the amplitudes of the input pulse and the calculated energy, which can be corrected using LUT(s). The timing is determined either directly by measuring the timing of first pulse generated by the 500MHz Σ-Δ ADC (timing resolution: 2ns), or by measuring the leading edge of the first pulse generated by FPGA differential input using a FPGA-based TDC.