| 摘要 |
Measurement circuits having a delta-sigma modulator are disclosed. One example measurement circuit includes a low pass filter coupled to receive an input voltage, a switched-capacitor integrator circuit, and a switched comparator circuit. The measurement circuit may generate a digital output made up of a sequence of logic high and logic low levels that are representative of a scaled value of the input voltage output by the low pass filter circuit. Also, by virtue of its switched-capacitor configuration, the electric charge received by the switched difference amplifier circuit may be returned to the input in a manner such that the input to the delta-sigma modulator takes little to no average current from the voltage it measures. In other words, the delta-sigma modulator may have a high input impedance by virtue of its switched-capacitor circuit configuration. |
| 主权项 |
1. A delta-sigma modulator circuit for a switched mode power converter controller, the delta-sigma modulator circuit comprising:
a low-pass filter circuit coupled to receive an input voltage to the switched mode power converter and configured to output a filtered input voltage; a switched capacitor coupled to selectively receive, at a first terminal of the switched capacitor, one of the filtered input voltage, a maximum boundary voltage, and a minimum boundary voltage, and to output, at a second terminal of the switched capacitor, an amount of electric charge,
wherein the amount of electric charge corresponds to the difference between the filtered input voltage and either the maximum boundary voltage or the minimum boundary voltage during a portion of a clock period; a switched-capacitor integrator circuit with an integrating capacitor, wherein the switched-capacitor integrator circuit is coupled to receive, at an input terminal, the electric charge, and to output, at an output terminal, an integral voltage based on the electric charge and a supply voltage; and a switched comparator circuit coupled to receive the integral voltage, compare the integral voltage with a reference voltage, and output a digital output signal representative of the filtered input voltage. |
