Abstract: The present invention provides a sub-ranging analog-to-digital (A/D) converter with improved speed and power consumption characteristics relative to known sub-ranging converters. The sub-ranging A/D converter utilizes information relating to the values of the bits determined in one stage to define the range of operation for a subsequent stage. In one embodiment, the subsequent stage utilizes three-input comparators in determining the value of a bit. Two of the inputs are used to receive signals representative of the upper and lower limits of the range of operation that has been determined by the prior stage and the other input is used to receive the analog signal. The three-input comparator operates to produce an output signal that is indicative of the relationship of the analog signal to a threshold level within the defined range of operation determined by the prior stage.
Abstract: A wideband buffer is described which has improved slew rate over prior buffers. In one embodiment the buffer includes (a) complementary buffer subcircuit, (b) first and second current mirrors to bias the buffer subcircuit in a cross coupled manner, and (c) means of setting a stable quiescent operating point for the circuit.
Abstract: An improved amplifier input circuit for use as the input stage for a current feedback amplifier to reduce offset and limit overload currents. The circuit includes first and second bias current supplies, first and second diodes having anode and cathode terminals, a PNP transistor and a NPN transistor, first and second input terminals, and first and second current sense terminals. Currents flowing through the sense terminals are sensitive to an input current in the first input terminal. Bias currents from the first and second bias current supplies are divided, respectively, between the PNP transistor and first diode, and the NPN transistor and second diode. The base terminals of the transistors are connected in common to the second input terminal. Other embodiments are also described.
Abstract: An improved current mirror is described which has utility as either a stand alone current source or as a gain block whenever current gain or transimpedance gain is required. When used as a current source the current mirror exhibits higher output impedance, and when used as a gain block, the current mirror exhibits improved higher frequency performance and high transimpedance gain than prior art current mirrors.
July 20, 1987
Date of Patent:
August 23, 1988
Kenneth R. Saller, Alan J. Baker, Steven O. Smith
Abstract: A wideband closed loop amplifier is described which has improved accuracy over prior amplifiers. The closed loop amplifier includes (a) first and second differential amplifiers, (b) floating bias means connected between the output terminals of the first and second differential amplifiers, (c) an output stage including first and second output transistors; and (d) first and second bias sources connected to the collector terminals of the respective output transistors.
Abstract: Compensation for the effect of parasitic and stray impedance which is present at the inverting input of known current feedback wideband amplifiers is described. The compensation permits these amplifiers to operate at higher frequencies without degrading the gain flatness of the amplifier and also simplifies the circuitry required to maintain correct biasing.
Abstract: Unity gain buffer amplifier circuits having a reduced input-to-output offset voltage characteristic are described. Compensation for the effects of base-to-emitter voltage variations and early voltage is employed.
Abstract: A wide-band direct-coupled transistor amplifier exhibits greatly improved settling time characteristics as the result of circuitry permitting the use of current feedback rather than voltage feedback in order to reduce the sensitivity of settling time and bandwidth to feedback elements without thereby affecting the manner in which feedback is applied externally by the user, reducing the sensitivity of settling time to the effects of temperature, eliminating saturation and turn-off problems within the amplifier that are related to bias control, to large input signals, and to high frequency input signals or those having fast rise times, and minimizing the sensitivity of settling time to power supply voltages.