التفاصيل البيبلوغرافية
| العنوان: |
Method and device for determining the ratio between an RC time constant in an integrated circuit and a set value |
| Document Number: |
20050035772 |
| تاريخ النشر: |
February 17, 2005 |
| Appl. No: |
10/884018 |
| Application Filed: |
July 02, 2004 |
| مستخلص: |
The invention relates to a method and a device for determining the ratio of the RC time constant of at least one RC element in an integrated circuit to a preset value, using a first reference RC element with a first resistor and a first capacitor, and a second reference RC element with a second resistor and a second capacitor, which elements are oppositely connected between a first and a second supply potential, wherein the product of the resistance value and the capacitance value of the two elements is equal in each case. |
| Inventors: |
Bauer, Achim (Villach, AT); Trojer, Martin (Klagenfurt, AT); Gaier, Ulrich (Velden, AT) |
| Claim: |
1. Method for determining the ratio of the RC time constant of at least one RC element in an integrated circuit to a preset value, the method comprising: providing a first reference RC element with a first resistor (R1) and a first capacitor (C1), and a second RC element with a second resistor (R2) and a second capacitor (C2), which are oppositely connected in the circuit between a first and second supply potential (VDD, VSS), the product obtained from the resistance value and capacitance value of the resistors (R1, R2) and the capacitors (C1, C2) of the two elements respectively being equal; defining a normalized RC time constant for the two reference RC elements (R1, C1 R2, C2); implementing successive charge and discharge cycles during a predetermined evaluation period, wherein the capacitors (C1, C2) are charged in a cycle during a charge time until the potential at a node (N1) common to the first resistor (R1) and the first capacitor (C1) of the first reference RC element approximately corresponds to the potential at a node (N2) common to the second resistor (R2) and the second capacitor (C2) of the second reference RC element, and whereby the capacitors are subsequently discharged for a discharge time, while the evaluation period is matched to the normalized RC time constant in such a way that, assuming the RC time constant of the reference RC elements corresponds to the normalized RC time constant, a predetermined number (N) of charge and discharge cycles can be implemented during this evaluation period; determining the number (P) of charge and discharge cycles actually implemented; providing a value that corresponds to a quotient of the actual number (P) and the predetermined number (N) in order to provide a measure of the ratio of the normalized RC time constant to the RC time constant of the reference RC elements. |
| Claim: |
2. Method according to claim 1, in which the discharge time (Tdis) is fixed. |
| Claim: |
3. Method according to claims 1, comprising: providing a clock signal (CLK) with a period duration (Tclk) which corresponds to the quotient of the evaluation time and the predetermined number (N), or which is in an integer divider ratio relative to this quotient; starting a counter counting the clock signal in time with the beginning of the charge and discharge cycles; ending the charge and discharge cycles whenever the counter has increased or decreased its count by a value corresponding to the predetermined number (N), or by a integral multiple of this value. |
| Claim: |
4. Method according to claim 1, in which one switch each (S1, S2) is provided in parallel to the first and second capacitors (C1, C2), and a comparator (K) is provided to compare the potentials at the first and second nodes (N1, N2), the switches (S1, S2) being discharged for a predetermined discharge time (Tdis) depending on a comparator signal. |
| Claim: |
5. Method according to claim 1, in which the comparator (K) controls a counter (10) which is reset at the beginning of the charge and discharge cycles, and which at the end of the charge and discharge cycles provides a value (P) corresponding to the number of charge and discharge cycles that have occurred. |
| Claim: |
6. Device for determining the ratio of the RC time constant of at least one RC element in an integrated circuit to a preset value, comprising: in the integrated circuit, a first reference RC element with a first resistor (R1) and a first capacitor (C1), and a second reference RC element with a second resistor (R2) and a second capacitor (C2), which are oppositely connected between a first and a second supply potential (VDD, VSS), the product of the resistance value and the capacitance value of the resistors (R1, R2) and capacitors (C1, C2) for the two elements being equal in each case; a comparator K with a first input which is connected to a node (N1) common to the first resistor (R1) and the first capacitor (C1), and with a second input which is connected to a node (N2) common to the second resistor (R2) and the second capacitor (C2); a counter (10), the count of which is increased or decreased by an output signal from the comparator (K) as clocked within an evaluation period; a first and second discharge circuit (S1, S2) which are connected to the first and second capacitors (C1, C2) and are designed to discharge the first and second capacitors (C1, C2) depending on the output signal of the comparator; means for the determining a quotient and a set value (N) that represents a measure for a normalized RC time constant of the reference RC elements from the count (P) of the counter (10). |
| Claim: |
7. Device according to claim 6, in which the discharge circuits each have switches (S1, S2) connected in parallel to the first and second capacitors (C1, C2). |
| Claim: |
8. (Cancelled) |
| Current U.S. Class: |
324712/000 |
| رقم الانضمام: |
edspap.20050035772 |
| قاعدة البيانات: |
USPTO Patent Applications |