Periodic waveform generating circuit

A periodic waveform generating circuit comprising:

• not less than two cascaded units each comprising
• first and second series circuits each comprising two semiconductor resistive elements having negative differential characteristics, an oscillating voltage source connected in series with said series-connected semiconductor resistive elements, and a three-terminal switching element connected in parallel with one of said semiconductor elements, and
• first connecting means for connecting a connection point of said two semiconductor resistive elements of said first series circuit to an input of said switching element of said second series circuit;
• second connecting means for connecting a connection point of said two semiconductor elements of said second series circuit in a last unit to an input of said switching element of said first series circuit of a first unit;
• and
• third connecting means provided between intermediate units to connect a connection point of said two semiconductor elements of said second series circuit in a preceding unit to an input of said switching element of said first series circuit in a succeeding unit,
• wherein said oscillating voltage sources of said first and second series circuits generate oscillating currents of opposite phases, thereby extracting a periodic signal from one node of elements constituting one of said series circuits in one of said units.

A periodic waveform generating circuit comprising a plurality of groups each comprising not less than two cascaded units each comprising

• first and second series circuits each comprising two semiconductor resistive elements having negative differential characteristics, an oscillating voltage source connected in series with said series-connected semiconductor resistive elements, and a three-terminal switching element connected in parallel with one of said semiconductor elements, and
• first connecting means for connecting a connection point of said two semiconductor resistive elements of said first series circuit to an input of said switching element of said second series circuit;
• second connecting means for connecting a connection point of said two semiconductor elements of said second series circuit in a last unit to an input of said switching element of said first series circuit of a first unit;
• and
• third connecting means provided between intermediate units to connect a connection point of said two semiconductor elements of said second series circuit in a preceding unit to an input of said switching element of said first series circuit in a succeeding unit,
• wherein in each of said groups, said oscillating voltage sources of said first and second series circuits generate oscillating currents of opposite phases, thereby extracting a periodic signal from one node of elements constituting one of said series circuits further comprising, and
• further comprising a logic circuit connected to one node of elements constituting one of said series circuits in one of said units in each group.