Abstract: An MOS transistor current source has a current mirror constructed of an MOS transistor pair with the transistors having intentionally mismatched W/L aspect ratios such that the intentionally mismatched transistor pair develops a mirror current that varies in an inversely proportional fashion to the process. A precision reference current drives a first, short channel device of the pair which develops a bias voltage which is coupled to the gate terminal of a second, long channel device of the pair. The long channel device conducts a current in operative response to the bias voltage, which current will increase or decrease a corresponding amount in an inversely proportional relationship to the drive strength of the short channel device.

Abstract: An integrated circuit is provided which allows tracking and compensation for shifts in a line receiver's input threshold caused by manufacturing process parameter and temperature variations. The circuit includes an input threshold reference circuit which develops a steady-state input threshold, the same as the input threshold of a line receiver circuit. The steady-state input threshold value is compared to a design reference value, implemented as a resistive voltage divider, which is insensitive to manufacturing process parameter and temperature variations. Input threshold references and reference voltages are compared and, depending on the magnitude and polarity of the difference between the steady-state input threshold and its design value, additional pull-up or pull-down transistors are switched into the conduction leg of the line receiver, in order to adjust the line receiver's input threshold to a value within the design input threshold margin budget.