Reception comparator

• US 5,539,778 A
• Filed: 09/16/1993
• Issued: 07/23/1996
• Est. Priority Date: 03/16/1991
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Fleischer, Ulrich, Elbracht, Berthold, Kienzler, Rainer
• Primary Examiner(s): TSE, YOUNG TOI
• Application Number:
  US08/119,092
• Time in Patent Office: 1,041 Days
• Field of Search: 375/257, 375/287-289, 375/317-318, 327/434, 327/208, 327/210, 327/389, 327/427
• US Class Current: 375/317
• CPC Class Codes: H04L 25/063 Setting decision thresholds using feedback techniques only

Abstract

A receiving comparator for a data-transmission system comprising at least one control unit and data-transmission lines, in particular for at least one Controller Area Network (CAN) controller and one CAN bus system having a CAN bus (CB) is proposed, which is distinguished by the feature that the individual circuit elements are monolithically integrated. By generating a switching threshold which is independent of the operating voltage and temperature with the aid of a current source (I_S), one prevents the CAN bus potentials from being asymmetrically influenced. The arrangement guarantees a processing of digital signals with a high data rate, whereby the input common-mode range extends up to above the supply voltage and to below ground.

Claims

1. A receiving comparator for a data-transmission system having at least one control unit and at least one data-transmission line, the receiving comparator comprising:

a signal conditioning device having an input for connection to the at least one data-transmission line, the signal conditioning device including an input divider for adjusting input potentials from the at least one data-transmission line;

a comparator circuit, coupled to the signal conditioning device and having a threshold-value generating device, the input divider including a reference-voltage source whose potential is selected to provide input signals to the comparator circuit which lie within a supply band;

a signal-amplifier stage coupled to the comparator circuit; and

an output stage coupled to the signal-amplifier stage;

wherein the signal conditioning device, comparator circuit, signal amplifier stage, and output stage are monolithically integrated.

2. The receiving comparator according to claim 1 wherein the input divider further includes at least one resistor coupled as a floating pan.

3. The receiving comparator according to claim 2, wherein the threshold-value generating device is a current source.

4. The receiving comparator according to claim 3 wherein the comparator circuit includes at least two reversed-feedback npn transistors.

5. The receiving comparator according to claim 4, wherein the output stage includes at least two MOS-transistors and at least one npn-transistor.

6. The receiving comparator according to claim 5, wherein the receiving comparator is part of a driver circuit which includes one transmitter output stage and preferably one tripping-logic circuit.