Output impedance

About: Output impedance is a research topic. Over the lifetime, 11185 publications have been published within this topic receiving 134949 citations.

Applications of a first-generation current conveyor in current-mode circuits

Abstract: In current-mode filter circuits which utilise a single current conveyor as the only active device, the first-generation current conveyor permits feedback of the response without connecting filter elements to the output port. Complex poles can be realised in such circuits while maintaining high output impedance. The utility of this observation is illustrated by the derivation of new second-order, complex-pole, current-mode, all-pass networks that employ a single current conveyor. Laboratory and simulation results are compared

Ultrawide-bandwidth low-noise optical receiver

Abstract: An ultrawide-bandwidth, low-noise optical receiver is disclosed. The receiver comprises a photodiode (402) connected to a high-impedance three-stage (421, 422, 423) HEMT preamplifier through an inductive/resistive modified T-network (404) the latter circuit enhancing the high-frequency response of the first stage. Each stage includes an HEMT amplifier (408, 408, 410) and an interstage microwave matching circuit (405, 406, 407) configured as a modified T-network having wire-bond inductances as the series-arm impedances and a coplanar waveguide in series with a resistor as the shunt-leg impedance. The first stage provides signal gain and transforms the high input impedance to an intermediate value. The second stage provides additional gain at the intermediate impedance level and the third stage provides output impedance matching to a conventional 50Ω system.

Electronic devices with adjustable bias impedances and adjustable bias voltages for accessories

Abstract: Electronic devices may provide microphone bias voltages to accessories. The accessories may include circuitry powered from the microphone bias voltages. The output impedances and the voltages of the microphone bias voltages may be adjusted during operation of the electronic devices. An electronic device may provide a bias voltage to an accessory, may lower the output impedance of the bias voltage, and may increase the voltage of the bias voltage during operation of the electronic device. Accessories that received bias voltages with lowered impedances or raised voltage levels may exhibit greater tolerance to faults such as moisture-based shorts and may be able to continue operating even in the presence of some faults.

Constant impedance, low noise CMOS buffer

Abstract: A low noise CMOS buffer has been provided which includes the advantages of having a stable load impedance and a linear-ramped current waveform at the output. The buffer adds waveform shaping transistors to delay the turn on of the driver circuits, and to shape the voltage and current waveforms of the drivers. These critically placed waveform shaping transistors accomplish the function of turning off the drivers in a manner to encourage an opposite polarity linear ramp current waveform at the buffer output. A method of using waveform shaping transistors to form a stable output impedance and a linear-ramped current waveform at the output of a buffer is also provided.