| 摘要 |
<p>A CMOS programmable resistor-based transconductor receives a differential input voltage and generates a differential output current. The transconductor includes a degenerate pair of transistors linearized by servo feedback, and further includes a string of series-connected resistors defining a group of tap points. Two selected tap points in the resistor string are selected by digital control of MOS switches and are connected, respectively, to the feedback input of the two amplifiers in the feedback loops. Because no DC current flows through the MOS switches into the high impedance inputs of the amplifiers, the differential input voltage is impressed across a portion of the resistor string residing between the two selected tap points, and the conversion gain is determined by the value of this portion of the resistor string.</p> |
