Abstract: A comparator compares an input voltage and a reference voltage and generates an output based on the comparison. The comparator may receive the input voltage in a normal mode of operation. Voltage band circuitry provides first and second test voltages to the comparator. The test voltages define a band around the reference voltage. An integrator adjusts an offset correction signal provided to the comparator based on outputs of the comparator that are generated using the test voltages. The output of the comparator that is generated using the first test voltage could be generated during a first auto-zeroing cycle. The output of the comparator that is generated using the second test voltage could be generated during a second auto-zeroing cycle. This technique helps to maintain the offset of the comparator with the band around the reference voltage.

Abstract: A biasing circuit is arranged to provide relatively well controlled startup and steady state behavior for a reference circuit such as noise immunity and reduced dependence on supplies. The biasing circuit initially employs an independent bias current for biasing the reference circuit at startup until a large enough bootstrapped (output voltage referenced) bias current can be generated that can take over the subsequent biasing of the circuit in the steady state. In one embodiment, a Power On Reset (POR) signal can be generated during the transition from an initial biasing of the reference circuit by the independent bias current to a subsequent steady state biasing provided by the bootstrapped bias current. Also, the assertion of the POR signal can be employed to turn off the transistors providing the independent bias current.