Abstract: A current-steering digital-to-analog converter may include dual current switch modules configured to receive digital input bits representative of desired analog output, and each dual current switch module may be controlled by one of the digital input bits. Each digital input bit may be represented by differential signals. The positive input and the negative input to drive two separate current switches in the dual current switch module may be separated, which may make the switching transition noise generated in the two current switches have a 180 degree phase difference. The output currents of these two current switches may be summed in proper phase to add the in-phase signal currents while canceling out the 180 degree out-of-phase switching noises generated in the two current switches. The 2nd order harmonic distortion and other higher even order harmonic distortions due to the common mode switching noise may be greatly reduced.

Abstract: A digital-circuit return-to-zero device and method for digital-to-analog conversion is disclosed that uses an internal multiplexer alternatively selecting, or selecting in a scheduled fashion, digital input data and an expansion code. By the using the disclosed multiplexing process, where the expansion code is a null code, the usable analog spectrum of the digital-to-analog converter (DAC) extends beyond that of DACs. With the multiplexing process applied to a complementary interpolation process, the disclosed device is adapted for selective enhancement of the frequency spectrum proximate to the clock frequency. While extending the usable frequency spectrum beyond conventional DACs, the present invention, in its several embodiments, features low complexity and high portability relative to known response expansion solutions.

Abstract: A distributed amplifier for wide-band, high power application is disclosed. The amplifier consists of an analysis module, a gain module and a synthesis module. In the analysis and synthesis modules, inductors such as transmission lines are connected to gain elements of the gain modules with a newly disclosed “pi” configuration, by which the number of inductors, or transmission lines, is reduced. This invention may be applied to wide-band and high-speed communications.

Abstract: A laser diode driver circuit is disclosed that uses a cascode output stage having high-impedance load and a matching network for reducing mismatch interference. Due to the high-impedance load, on-chip dummy current is less than that required for laser diode drivers with matched loads. Accordingly, the number of transistors of said output stage can be reduced. Moreover, with an AC-coupled active load circuit replacing the matched resistance of the matching network, the power efficiency is improved. A laser diode driver circuit, in accordance with the present invention, can be applied to an optical transmitter with low power requirement.

Abstract: A circuit for a variable gain amplifier is disclosed that uses two differential gain stages with independently adjustable bias currents. By changing the bias currents of the gain stages, the overall gain and phase of the amplifier can be adjusted over a wide range. Neither in-series nor in-parallel circuitry is required to implement or perform gain control. In addition to minimal part requirements for mechanization, the present invention features low power supply requirements while maintaining a wide operational bandwidth.