Abstract: A power cut detection and recovery system (36) provides for the recovery of an electronic apparatus (20) in response to a momentary interruption in the voltage level of a power supply (46) coupled to that apparatus. The system includes a level detecting circuit (80) coupled to the power supply (46) for monitoring the voltage supplied to the apparatus (20). The system further includes internal reference supply circuits (86) that provide voltage and current references to operate the apparatus (20). A power cut monitor and reference control circuit (84) is coupled to the level detecting circuit (80) and is capable of causing the internal reference supply circuits (86) to remain enabled upon the detection of a momentary cut in the externally supplied power (46).

Abstract: A comparator circuit (10) with hysteresis having transistors with the same threshold voltage and a method for comparing input signals. The comparator circuit (10) includes a current mirror (11) coupled to a common electrode differential pair (12) and to a feedback circuit (13). The current mirror (11) has a large output impedance and provides a plurality of output currents (I.sub.21, I.sub.26, I.sub.31). Some (I.sub.21, I.sub.26) of the currents are transmitted to the common electrode differential pair and one (I.sub.31) of the currents is transmitted to the feedback circuit (13). The output currents (I.sub.21, I.sub.26, I.sub.31) are modulated to generate positive feedback signals that control changing the output state of the comparator circuit (10) as well as provide hysteresis for the comparator circuit (10).

Abstract: Low voltage operational amplifier (10) operates in a voltage range of one to eight volts over a temperature range of 0.degree. to 70.degree. centigrade. Op amp input stage (12) uses N-channel depletion-mode MOSFETs to provide amplification of the differential input and maintain constant transconductance. Source follower MOSFET (13) provides unity gain in transferring the AC signal, STAGE-1 OUTPUT, to the base of current sinking transistor (18). Sink control circuit (14) and source control circuit (22) generate the base drive currents for in transistors (18) and (24). The signal at the output of MOSFET (13) either causes the sink transistor (18) to sink current or the signal to be transposed by means of a translinear loop (16) and causes the source transistor (24) to source current.

Abstract: Low voltage operational amplifier (10) operates in a voltage range of one to eight volts over a temperature range of 0.degree. to 70.degree. centigrade. Op amp input stage (12) uses N-channel depletion-mode MOSFETs to provide amplification of the differential input and maintain constant transconductance. Source follower MOSFET (13) provides unity gain in transferring the AC signal, STAGE-1 OUTPUT, to the base of current sinking transistor (18). Sink control circuit (14) and source control circuit (22) generate the base drive currents for transistors (18) and (24). The signal at the output of MOSFET (13) either causes the sink transistor (18) to sink current or the signal to be transposed by means of a translinear loop (16) and causes the source transistor (24) to source current. An output stage provides approximately fifty milliamps of current drive and is quiescent until the output driver is selected.

Abstract: A trim circuit (10) and method of reducing offset voltages in a differential input stage. The differential input transistors (32 and 42) have separate bulk terminals for receiving a voltage to compensate for the input offset voltage. A current source (60) supplies a static current to the offset compensation circuit for generating a bias voltage at node (55). The transistors (64 and 66) receive a voltage at input terminals (30 and 40) and supply an additional current to an offset compensation circuit (20). A switch circuit (50) has switch pairs (52, 56, and 54, 58) for transferring a voltage to the bulk terminal of one of the differential transistors (32 and 42) while grounding the bulk terminal of the other transistor. The differential voltage supplied across the bulk terminals of transistors (32 and 42) changes the threshold voltage of the transistors reducing the offset voltage of the input stage.

Abstract: Low voltage operational amplifier (10) operates in a voltage range of one to eight volts over a temperature range of 0.degree. to 70.degree. centigrade. Op amp input stage (12) uses N-channel depletion-mode MOSFETs to provide amplification of the differential input and maintain constant transconductance. Source follower MOSFET (13) provides unity gain in transferring the AC signal, STAGE-1 OUTPUT, to the base of current sinking transistor (18). Sink control circuit (14) and source control circuit (22) generate the base drive currents for transistors (18) and (24). The signal at the output of MOSFET (13) either causes the sink transistor (18) to sink current or the signal to be transposed by means of a translinear loop (16) and causes the source transistor (24) to source current.