Pulse modulator

Abstract

A pulse modulator comprises a solid state power switch having a source, a drain, a gate and a separate gate drive connected to ground. One pulse modulator comprises a plurality of stages connected as an induction adder. Each stage includes a plurality of cells and at least some of the cells each include a solid state power switch having a source, a drain, a gate and a separate gate drive connected to ground to control the discharge of a capacitor. In one embodiment the solid state power switch is a power MOSFET.

1 . A pulse modulator comprising: a solid state power switch having a source, a drain, a gate and a separate gate drive connected to ground. 
     
     
         2 . The pulse modulator as claimed in  claim 1 , wherein the solid state power switch comprises a plurality of solid state power switches, the pulse modulator further comprising a plurality of stages, each stage including a plurality of cells, and at least some of the cells each including a-at least one of the solid state power switches. 
     
     
         3 . The pulse modulator as claimed in  claim 2 , wherein the plurality of stages is connected as an induction adder. 
     
     
         4 . The pulse modulator as claimed in  claim 1 , wherein the solid state power switch is a power MOSFET. 
     
     
         5 . The pulse modulator as claimed in  claim 2  wherein said at least some of the cells each include a gate driver and a balun, the gate driver being connected to the gate of the solid state power switch via the balun. 
     
     
         6 . The pulse modulator as claimed in  claim 2  wherein said at least some of the cells each include a Zener diode via which the separate gate drive is connected to ground. 
     
     
         7 . The pulse modulator as claimed in  claim 1 , further including a diode in series with the solid state power switch. 
     
     
         8 . The pulse modulator as claimed in  claim 7  wherein the diode is a Schottky diode. 
     
     
         9 . The pulse modulator as claimed in  claim 2 , wherein said at least some of the cells each include more than one of said solid state power switches having a source, a drain, a gate and a separate gate drive connected to ground. 
     
     
         10 . The pulse modulator as claimed in  claim 2 , wherein each stage includes a magnetic induction core, a single turn primary winding and a single turn secondary winding and the secondary windings are connected in series. 
     
     
         11 . The pulse modulator as claimed in  claim 2 , wherein said at least some of the cells each include a capacitor which is connected to be discharged by the solid state power switch to generate pulses. 
     
     
         12 . The pulse modulator as claimed in  claim 1 , wherein the pulse modulator is operative to generate pulses having a pulse rise time of less than 5 ns and pulse length in the range 15 ns to 20 ns. 
     
     
         13 . The pulse modulator as claimed in  claim 1 , wherein the pulse modulator is operative to generate pulses having repetition rate of greater than 1000 pps. 
     
     
         14 . The pulse modulator as claimed in  claim 13 , wherein the pulse modulator is operative to generate pulses having repetition rate of greater than 1 megaHertz. 
     
     
         15 . The pulse modulator as claimed in  claim 1 , wherein the pulse modulator is aoperative to generate pulses with a peak power of the order of tens of megawatts. 
     
     
         16 . The pulse modulator as claimed in  claim 15 , wherein the pulse modulator is operative to generate pulses with a peak power in the range 30 to 40 MW. 
     
     
         17 . The pulse modulator as claimed in  claim 2 , wherein each stage has dimensions of less than or equal to 120 mm×240 mm. 
     
     
         18 . The pulse modulator as claimed in  claim 2 , wherein the cells of the plurality of cells are nominally identical. 
     
     
         19 . The pulse modulator as claimed in  claim 2 , further including a non-linear snubber network to dissipate reflected energy in at least one of the cells. 
     
     
         20 . A system comprising a pulse modulator as claimed in  claim 1 , further including a load, the pulse modulator being connected to apply pulses across the load. 
     
     
         21 . (canceled)