Patent ID: 7679458

Claim:
A circuit comprising: a first multiplexer with an output lead, a select input lead, a first data input lead and a second data input lead; and a second multiplexer with an output lead and a select input lead, wherein the first multiplexer and the second multiplexer have substantially identical structures, wherein the output lead of the second multiplexer is coupled to the select input lead of the first multiplexer, wherein an oscillating signal is present on the output lead of the second multiplexer, wherein the output lead of the first multiplexer is coupled to the select input lead of the second multiplexer, wherein a first logic level is constantly present on the first data input lead of the first multiplexer and a second logic level is constantly present on the second data input lead of the first multiplexer, and wherein the first and second multiplexers are powered by a supply voltage that can be set to a predetermined level to vary the supply voltage.