Radiation-hardened break before make circuit
View Patent ↗A break-before-make (BB4M) circuit topology is disclosed for use with a multiplexer that eliminates shoot-through current between analog inputs and also between an analog input and analog output. The BB4M circuit generates a pulse that disables an existing selected channel before enabling a newly selected channel or gate driver, and is suitable for use in high-radiation or outer space operating environments.
1. A radiation hardened break-before-make system comprising:
a break-before-make circuit for receiving a plurality of address select lines and for generating a plurality of delayed address select lines and a delayed global break-before-make pulse;
an address decoder for receiving the plurality of delayed address select lines and for generating a plurality of address decoder output signals; and
a plurality of AND gates for receiving the delayed global break-before-make pulse and the plurality of address decoder output signals for generating a plurality of select output signals,
wherein delays in the break-before-make circuit to generate the plurality of delayed address select lines and the delayed global break-before-make pulse are generated only with resistor-capacitor circuits and no latches, flip-flops, or cross-coupled structures are used to generate the delays.
2. The break-before-make system of claim 1 further comprising a multiplexer for receiving the plurality of select output signals.
3. The break-before-make system of claim 1 wherein the break-before-make pulse is configured to disable the address decoder.
4. The break-before-make system of claim 2 wherein the break-before-make pulse is configured to disable all input channels of the multiplexer.
5. The break-before-make system of claim 2 wherein the break-before-make pulse is configured to delay the selection of a new channel of the multiplexer.
6. The break-before-make system of claim 2 wherein the break-before-make pulse is configured to prevent an unintentional transient current path between a previous input source and new input source of the multiplexer.
7. The break-before-make system of claim 1 , wherein the break-before-make circuit is configured to ensure that when any address makes a transition a new address/select line is not decoded before the break-before-pulse becomes enabled.