A Generator of Rectangular Pulses Based on a Serial Connection of Mosfet with Umax = 4500 V

Abstract

The purpose of the article is to show the advantages of a new design of a high-voltage rectangular pulse generator. Known analogues combine modules: signal generator; high-voltage key of N identical transistors (Q_k, k = 1….N) connected in series; gate driver of leading Q_k; high-voltage power source, its electromotive force, emf (E), feeds all Q_k and load (R) of the key. In analogs, divider resistors (r_k) and snubbers balance equality of voltages U_k on all Q_k. Under nonideal balance conditions E ≈ 0.7NU_max, where U_max is the maximum operating voltage of Q_k. The new solution differs in that the high-voltage power source sets not one but N emf E_k (E_i/E_j = const (i, j); i ≠ j; i, j = 1, 2, …, N) and each E_k feeds its Q_k through the load R_k. Experiments and simulations have revealed advantages of the new design: (1) the simplicity of the circuit and key tuning, (2) the fast transition ON→OFF for all Q_k (as R_k is small, R_k \( \ll \) r_k), (3) the high pulse repetition rate, and (4) the greatly improved balancing of U_k voltages allows the E_k emf to be set so that ΣU_k ≈ ΣU_{k, max} at U_i, max ≠ U_k, max. The generator with the key based on two different MOSFETs (IXTL2N450 and IXTT1N450HV, U_max = 4500 V) and with a source where the E₂ = 2E₁ were used to excite vacuum ion emission from liquid Ga-based alloys.