Calibration circuit

• US 6,885,181 B1
• Filed: 03/04/2003
• Issued: 04/26/2005
• Est. Priority Date: 07/31/2000
• Status: Expired due to Term

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Roo, Pierte
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): Nguyen, Jimmy
• Application Number:
  US10/379,260
• Time in Patent Office: 784 Days
• Field of Search: 324/76.28, 324/158.1, 324/601, 324/76.29, 438/14, 438/17, 438/18, 702/85, 702/106, 702/107, 327/553, 327/558, 327/552
• US Class Current: 324/76.28
• CPC Class Codes: H03H 11/1291 Current or voltage controlled filters
• CPC Class Codes: H03J 2200/10 Tuning of a resonator by means of digitally controlled capacitor bank

Abstract

An apparatus is provided to calibrate a target electrical circuit. The target electrical circuit includes at least a first variable capacitor and a first resistive element. The apparatus includes a second variable capacitor proportionally matched to the first variable capacitor. The apparatus also includes a measurement branch having at least a second resistive element proportionally matched to the first resistive element, and a current generator to generate a current proportionally matched to a predicted current of the target circuit. The apparatus also includes

a digital loop to generate a digital code based on at least a comparison between a first voltage signal of the measurement branch and a predetermined voltage.

Claims

1. A calibration circuit comprising:

a first capacitor comprising;

a plurality of parallel capacitors, wherein at least one parallel capacitor of the plurality of parallel capacitors communicates with a switch, and the switch is operated with a digital signal; and

a digital loop including an output in communication with at least the switch of the one parallel capacitor, the digital loop generating a digital signal and communicating the digital signal to at least the switch, wherein the digital signal is varied to reach a steady-state for the calibration circuit.

2. The calibration circuit according to claim 1, further comprising a first resistor including a plurality of resistive elements, wherein at least one resistive element of the plurality of resistive elements communicates with a second switch, and the second switch is operated with the digital signal, and wherein the output of the digital loop is in communication with the second switch.

3. The calibration circuit according to claim 2, further comprising an output including the digital signal.

4. A calibration circuit comprising:

first means for providing capacitance comprising;

a plurality of parallel means for providing;

capacitance, wherein at least one parallel providing capacitance means communicates with means for switching, and the switching means is operated with a digital signal; and

means for generating a digital signal including an output in communication with at least the switching means of the one parallel means for providing capacitance, the generating means generating a digital signal and communicating the digital signal to at least the switching means, wherein the digital signal is varied to reach a steady-state for the calibration circuit.

5. The calibration circuit according to claim 4, further comprising a first resistor including a plurality of resistive elements, wherein at least one resistive element of the plurality of resistive elements communicates with a second switch, and the second switch is operated with the digital signal, and wherein the output of the digital loop is in communication with the second switch.

6. The calibration circuit according to claim 5, further comprising an output including the digital signal.