| 摘要 |
<p>A frequency-to-current converter includes several capacitances with capacitive values that are effectively multiplied. After each of a series of periodic pulses, the voltage on a "ramp" capacitance is charged to a starting voltage. Then, during the period preceding the subsequent pulse, the ramp capacitance is allowed to discharge at a discharge rate that is a function of a voltage on a discharge-current bias capacitance. At the end of the period, the voltage on the ramp capacitance is sampled and compared to a reference. If the voltage on the ramp capacitance is too low or too high, indicating a discharge current that is too high or too low, respectively, the bias voltage on the bias capacitance is adjusted to compensate for the error. In another embodiment, a small ramp capacitance is repetitively charged and discharged between two reference voltage levels using alternating charge and discharge current levels. The charge and discharge current levels are related to output current levels so that the rate at which the ramp capacitance transitions between the two reference voltages provides an indication of the output current. <IMAGE></p> |
