Abstract: A trimmable comparator. The novel comparator includes a first circuit for comparing first and second input signals and in accordance therewith generating first and second output signals, and a second circuit for adding an adjustable current to the first output signal such that the comparator is in a transition state when the first and/or second input signals are at desired levels. The comparator may also include a third circuit for adding an adjustable current to the second output signal. In the illustrative embodiments, the second and third circuits are implemented using adjustable current sources with trimmable resistors, or using digital to analog converters. The novel comparators may be used in an analog to digital converter to allow the converter thresholds to be adjusted to desired levels.

Abstract: An output driver. The novel output driver includes a first circuit for receiving an input signal and in accordance therewith generating an output signal at an output node, a second circuit for applying a variable current to the output node, and a third circuit for controlling the magnitude of the variable current in accordance with the input signal. In an illustrative embodiment, the third circuit is adapted to generate a controlling current in accordance with the input signal, and the second circuit includes a current mirror adapted to receive the controlling current and output a scaled version of the controlling current to the output node.

Abstract: A clamped comparator. The novel comparator includes a first circuit for comparing first and second input signals and generating a digital output, and a second circuit for receiving a control signal and in accordance therewith decoupling the input signals from the output. The second circuit includes one or more switching circuits adapted to clamp the signal path between the input signals and the output when the circuit is operating in a ‘mute’ mode. In an illustrative embodiment, the comparator also includes a pre-amplifier with an amplifier stage, and the switching circuit is adapted to turn off the amplifier stage and/or steer the outputs of the amplifier stage out of the signal path, when the circuit is in the ‘mute’ mode.

Abstract: A DAC (10) including an operational amplifier (12) having an input terminal; a plurality of current paths coupled to the input terminal; a plurality of current sources (I1/2-I4/2); and an arrangement (11) for switchably coupling current from at least two of the cells to a respective one of the paths in response to an input signal. In a specific embodiment, the inventive DAC (10) further includes a first resistive element (2R1-2R4) disposed in each of the current paths, a second resistive element (R1-R4) disposed between the current paths, and a feedback resistor (RF) disposed between an output terminal of the amplifier and the input terminal thereof. In the illustrative embodiment, the coupling arrangement includes a plurality of switches (SW1-SW4); each of the switches is adapted to switch half of the current from a first source and half of the current from a second source into a respective one of the paths.

Abstract: A subtraction circuit. The novel subtraction circuit includes a first circuit for providing an impedance between an input node and an output node, a second circuit for generating a first current and applying the first current to the output node to produce a desired voltage drop between the input and output nodes, and a third circuit for independently generating a second current relative to the first current and applying the second current to the input node to regulate a current input to the first circuit at the input node. The second and third circuits are implemented using two digital to analog converters (DACs), a precision DAC for generating the first current and a non-trimmed “dummy” DAC for generating the second current. In an illustrative embodiment, the subtraction circuit is used in the reconstruction stage of a subranging analog to digital converter.