×

Polarity switched data bus for reduced electromagnetic interference

  • US 5,748,902 A
  • Filed: 07/19/1996
  • Issued: 05/05/1998
  • Est. Priority Date: 07/19/1996
  • Status: Expired due to Term
First Claim
Patent Images

1. A system for passing data items of m bits over a data bus with reduced electromagnetic interference, the system comprising:

  • a data bus with a data polarity line that carries a data polarity signal and with m data lines that carry polarity adjusted data items;

    a data transmission circuit coupled to the data bus and receiving the data items, the data transmission circuit including;

    storage that holds a first data item of the received data items;

    a bit level comparison circuit coupled to the storage and receiving a second data item of the received data items, the bit level comparison circuit providing an indication of whether over m/2 of the bits in the first and second data items are different; and

    a polarity adjusted output circuit receiving the first and second data items, having a polarity output and polarity adjusted data outputs, and responsive to the indication of whether over m/2 of the bits in the first and second data items are different, said polarity adjusted output circuit adapted to provide a first polarity signal on its polarity output and a first polarity adjusted data item on its polarity adjusted data outputs at a first polarity corresponding to the first polarity signal, and to provide a second polarity signal on its polarity output and a second polarity adjusted data item on its polarity adjusted data outputs at a second polarity corresponding to the second polarity signal, wherein the polarity adjusted output circuit provides the second polarity signal to indicate the opposite polarity as the first polarity signal in response to the indication indicating that over m/2 bits are different.

View all claims
  • 3 Assignments
Timeline View
Assignment View
    ×
    ×