Patent ID: 7489488

Claim:
An overvoltage protection circuit, comprising: a reference voltage and a different reference voltage; a first pair of diodes with cathodes thereof connected together to form a first circuit junction, and a second pair of diodes with anodes thereof connected together to form a second circuit junction, said first and second pairs of diodes defining a bridge circuit; an overvoltage protection device connected between said first circuit junction and said second circuit junction, said overvoltage protection device having a characteristic breakover voltage when biased in a reverse direction; a first resistor having one terminal connected to said first circuit junction, and another terminal of said first resistor adapted for connection to said reference voltage; a second resistor having one terminal connected to said second circuit junction, and another terminal of said second resistor adapted for connection to said different reference voltage; a difference between a voltage of said reference voltage and a voltage of said different reference voltage is less than the breakover voltage of said overvoltage protection device; whereby said reference voltage is effective to reduce a capacitance of said overvoltage protection device; and said first and second diode pairs, said overvoltage protection circuit, and said first and second resistors are formed in a single semiconductor chip.