Abstract: A current source is selectively switched into the output circuit of a differential amplifier for producing hysteresis. In a circuit embodying the invention, a differential amplifier (diff-amp) stage operated at a first current level set by a first current source has first and second input terminals for the application therebetween of a differential input signal and first and second output nodes for the production of differential output signals. A second current source for inducing hysteresis is connected to one of the output nodes of the diff-amp and is selectively enabled. A differential input signal (VIN) is applied across the input terminals. When VIN varies in one direction and reaches a first threshold level, the second, hysteresis inducing, current source is enabled whereby a larger current can flow in the one node. VIN then has to vary in the opposite direction and reach a second threshold level to disable the second current source.

Abstract: A normally non-conducting control device whose turn-on threshold decreases with increasing temperature is supplied with a control voltage which increases with temperature for causing a more rapid increase in the conduction of the control device when a predetermined temperature is exceeded.

Abstract: A multiplexed sigma delta analog-to-digital (A/D) converter for low frequency applications has a single oversampling modulator together with a relatively high cutoff lowpass filter together with individual line frequency (50 or 60 Hz) rejection filters for each output channel.

Abstract: This invention relates to a capacitive switching network for producing signals of opposite polarity. In one embodiment of the invention, a first signal (V1) is applied to the first plate of a first capacitor (C1) and a second signal (V2) is applied to the first plate of a second capacitor (C2). The first plates of the first and second capacitors are then shorted together to produce a combined voltage (Vc). The generation of Vc causes an AC voltage equal to (Vc-V1) to be produced at the second plate of C1 and an AC voltage equal to (Vc-V2) to be produced at the second plate of C2. By way of example, for C1 equal to C2, there is produced a Vc equal to (V1+V2)/2. Furthermore, if V1 is greater than V2, a negative going AC signal equal to (VC-V1) is produced at the second plate of C1, and a positive going AC signal equal to (Vc-V2) is produced at the second plate of C2. The capacitive network of the invention is highly suited for use in high speed differential comparators.