Abstract: Direct-coupled laser diode drivers are provided which eliminate the need for conventional coupling elements (e.g., capacitors and inductors) that typically introduce timing inacurracies and add complexity, size and cost to conventional drivers. The drivers are structured to reduce power dissipation and maintain sufficient transistor headroom to enhance response time and dynamic range. An exemplary driver responds to data pulses that are defined by first and second pulse levels and includes a current source that generates an imod/n current, a current mirror connected to receive the imod/n current and, in response, drive a modulation current imod through the laser diode and a differential pair of transistors that steers the imod/n current away from the modulation current mirror in response to the first pulse levels so that the modulation current mirror drives imod current pulses through the laser diode during the second pulse levels with no need for coupling elements.

Abstract: Comparator methods and structures are provided whose accuracy in analyzing an output signal Sout of a DUT is enhanced because they compensate for a signal distortion that is imposed by a transmission path over which the output signal Sout is received. The methods include the steps of a) providing a reference signal Sref; b) combining the reference signal Sref with a reference distortion that corresponds to the signal distortion to thereby realize a compensated reference signal Scmp-ref; and c) comparing the output signal Sout to the compensated reference signal Scmp-ref to determine signal parameters of the output signal Sout. The methods of the invention facilitate the use of simple comparator structures that do not significantly increase the cost of automatic test equipment but which do significantly increase accuracy of signal analysis.

Abstract: Waveform synthesizers are disclosed that generate an output signal S.sub.OUT with independent response to a common-mode input signal S.sub.CM, an input data signal S.sub.D and a current programming signal S.sub.PRGM. The synthesizers include a differential pair of first and second transistors that respectively respond to the input data signal S.sub.D and to a fixed reference signal V.sub.REF. Because the second transistor is referenced to a fixed potential, current-pumping action of parasitic capacitances is reduced with consequent reduction of transient signals in the output signal S.sub.OUT. Signal transients are further reduced with diodes that are arranged to block transient-current interchange between the first and second transistors.

Abstract: Comparator structures are shown which improve latching accuracy and enhance bandwidth for operations such as high-speed sampling in a variety of applications (e.g., analog-to-digital converters and automatic test equipment). The structures include an input differential pair of transistors having first and second control structures, a differential output amplifier and a clamp that limits the signal level of at least one of the first and second control structures. The clamp includes first and second Schottky diodes that are oppositely oriented and coupled between the first and second control structures. Altenatively one side of the diodes can be coupled to bias structures that respond to a threshold signal. Bias networks respond to a sampling threshold signal and stabilize biases in the input differential pair and the differential output amplifier.