Digital-to-analog converter comprising an integrated test circuit

• US 20050162293A1
• Filed: 05/13/2002
• Published: 07/28/2005
• Est. Priority Date: 05/13/2002
• Status: Active Grant

• Current Assignee: ams AG (Ams-Osram AG)
• Original Assignee: ams AG (Ams-Osram AG)
• Inventors: Theiler, Helmut
• Granted Patent: US 7,026,966 B2
• Time in Patent Office: Days
• US Class Current: 341/120
• CPC Class Codes: H03M 1/108 Converters having special provisions for facilitating access for testing purposes
• CPC Class Codes: H03M 1/66 Digital/analogue converters H03M1/001 – H03M1/10 take precedence

Abstract

In a digital-to-analog converter including an integrated test circuit, a digital input and an analog output, a comparator (5) capable of being connected with the analog output (4) and including a connection (7) for a reference voltage source, a digital test connection (11) and a logic element is provided, the logic element being connected with the test connection (11) for emitting the digital value 0 or 1 as a function of the difference between the voltage at the analog output (4) and the reference voltage.

Claims

1. A digital-to-analog converter including an integrated test circuit, a digital input and an analog output, characterized in that a comparator (5) capable of being connected with the analog output (4) and comprising a connection (7) for a reference voltage source, a digital test connection (11) and a logic element is provided, said logic element being connected with the test connection (11) for emitting the digital value 0 or 1 as a function of the difference between the voltage at the analog output (4) and the reference voltage.

2. A digital-to-analog converter according to claim 1, characterized in that the connection (7) for the reference voltage source is connected with the analog output (4) via a switch (10)

3. A digital-to-analog converter according to claim 1, characterized in that the reference voltage source is comprised of a capacitor (8).

4. A digital-to-analog converter according to claim 1, characterized in that the digital-to-analog converter (1) is designed as a power DA converter comprising a consecutively arranged operation amplifier (2).

5. A digital-to-analog converter according to claim 2, characterized in that the digital-to-analog converter (1), the comparator (5) and optionally the capacitor (8) are designed as an integrated circuit.

6. A method for determining the transient period of a digital-to-analog converter, characterized by the steps of:

applying to the input of the digital-to-analog converter a digital word corresponding to a stored analog target value, comparing the analog signal at the output of the digital-to-analog converter with the stored analog target value,

generating a digitally evaluatable signal as soon as the difference between the analog signal at the output of the digital-to-analog converter and the stored analog target value has become smaller than the transient tolerance,

measuring the time between the application of the digital word to the input of the digital-to-analog converter and the generation of the digitally evaluatable signal.