Resistor self-trim circuit for increased performance

An apparatus comprising:

• a differential amplifier having a common mode feedback loop (CMFBL), the CMFBL being capable of operating in a closed loop mode and an open loop mode, wherein the CMFBL operating in the closed loop mode provides control of a regulated current supplied to load resistors, wherein the CMFBL operating in the open loop mode enables values of the load resistors to be trimmed;
• and
• a selector switch coupled to receive an output signal of the CMFBL, the selector switch being controlled by a CAL signal to switch a path of the output signal in accordance with the closed loop mode and the open loop mode;
• and
• a controller operable to receive the output signal from the selector switch in the open loop mode and provide a digital trim signal to trim the values of the load resistors.

An apparatus comprising:

• a differential amplifier having a common mode feedback loop (CMFBL), the CMFBL being capable of operating in a closed loop mode and an open loop mode, wherein the CMFBL operating in the closed loop mode provides control of a regulated current supplied to load resistors, wherein the CMFBL operating in the open loop mode enables values of the load resistors to be trimmed;
• a first switch coupled to receive an output signal of the CMFBL, the first switch being controlled by an inverse of a CAL signal to place the CMFBL in one of the closed loop mode and the open loop mode;
• a second switch coupled to receive the output signal, the second switch being controlled by the CAL signal, the second switch operating in the open loop mode redirects the output signal to enable the load resistors to be trimmed;
• and
• a controller operable to receive the output signal from the second switch in the open loop mode and provide a digital trim signal to trim the values of the load resistors.