Abstract: A bipolar high impedance element comprises a p-n diode made from a compound semiconductor, and circuitry arranged to reverse-bias the diode such that the diode conducts a nearly constant current—thereby enabling the element to be employed as a high impedance element. The diode is preferably the base-emitter junction of a transistor made from a compound semiconductor like InP, such that an on-chip high impedance element is provided for a fabrication process such as that used for HBTs. The element is suitably employed in an active low pass filter design: the element is connected between an input signal and an op amp input, and a feedback capacitor is connected between the op amp's output and input. The resulting filter's time constant varies with the reverse-biased diode's impedance and the capacitance of the feedback capacitor.

Abstract: Method and system for reducing parasitic feedback and resonances in high-gain transimpedance amplifiers. In a first embodiment of the present invention, a resistive layer is implemented in the gaps of a high-gain transimpedance amplifier's metallic planes. In a second embodiment of the present invention, a resistive layer is implemented underneath a high-gain transimpedance amplifier's ground plane, vias are implemented to create contact between the resistive layer and the ground plane.

Abstract: Method and system for a diode shunting configuration wherein the configuration prevents a transimpedance amplifier from saturation while maintaining high transimpedance gain and bandwidth. In one embodiment of the present invention, a diode is coupled to the input of a transimpedance amplifier in order to prevent the transimpedance amplifier from saturation. Moreover, the diode serves to divert current such that in cases where the input current is low the diode never turns on and only represents a minimal, mostly capacitive load on the input; in cases where the input current is high, the diode conducts and diverts any excess input current from the transimpedance amplifier.

Abstract: A latching comparator and associated method are disclosed that utilize resonant tunneling diodes, or other two-terminal devices possessing regions of negative differential operating resistance in their current-voltage characteristics, and Schottky diodes to provide high speed and reliable analog to digital conversions. In one embodiment, the latching comparator includes a differential amplifier, resonant tunneling diodes, and cross-coupled resistors. The latching comparator may include mode selection circuitry having a track mode signal and a latch mode signal as inputs. In addition, the latching comparator may include a plurality of Schottky diodes connected in series with the resonant tunneling diodes and the cross-coupled resistors.