Telefonaktiebolaget Lm Ericsson (publ)

Heinz B Mader

Tord L Haulin

Per M Segerback

Carl-Gustaf Thisell

Johan U Tingsborg

Malcolm Hardie

Anders Bjorklid

A voltage controlled oscillator (VCO), for use in a phase locked loop for clock multiplication, for example in recovery of data pulses from a data stream input comprising digital data with unknown phase. According to the invention, the VCO comprises a plurality of VCO stages, each stage being implemented as a differential amplifier. The amplifier load is formed of two cross-coupled gate devices and of two gate devices which are connected as diodes. The differential input is applied to a source coupled input pair as well as to two pull-down gate devices.

Voltage controlled oscillator for recovering data pulses from a data

A bit synchronizer for the interpretation of a bit data stream received in a receiver when strobed by an isochronous or plesiochronous clock signal which lies in the receiver time domain is disclosed. This is achieved by alternate activation and deactivation of a first and a second phase aligner respectively, based on monitoring a delay controlled voltage of the active phase aligner. These phase aligners each utilizes differential delay lines which are comprised of differential delay elements, which in turn are comprised of pairs of inverting devices, where both devices of each pair have a controllable delay for positive edges and a pulse form restoring function for negative edges, alternatively a controllable delay for negative edges and a pulse form restoring function for positive edges. Because each DDE is constructed symmetrically, feedback from the outputs Q and Q on INV2 can be easily effected to the inputs FB and FB on INV1, and from the outputs Q and Q on INV1 in a delay element can be readily fed back to the inputs FB and FB respectively on INV2 in the preceding delay element. Because the feedback route quickly changes the ramp edge to full logic level as soon as the threshold voltage has been reached in the inverting device, the preceding stage is prepared for the restoring function that it will have for the next data edge, thereby avoiding interference effects.

Bit synchronizer

A circuit for regenerating a clock signal from an NRZ encoded signal. The NRZ signal is filtered, differentiated, and applied to a nested phase-locked loop. The main loop of the phase-locked loop includes a voltage controlled crystal oscillator. The inner loop of the nested phase-locked loop includes a voltage controlled oscillator which multiplies the frequency of the signal provided by the crystal oscillator to obtain the regenerated clock signal. Tunable low pass filters are used in the differentiating circuit as delay elements. The voltage controlled oscillator includes a tunable low pass filter and an integrator. The control voltage for the inner loop voltage controlled oscillator is used to control the low pass filters of the differentiating circuit in a frequency locked loop.

Clock extraction circuit for fiber optic receivers

A limiting amplifier has between an amplifier input and an amplifier output at least one amplifier stage as well as load components. The amplifier has an output signal limiting device for limiting the maximum amplitude of the output signal and the amplification and includes a current drain device connected to the amplifier stage output and drawing current through the load components. More particularly, the amplifier stage can be a differential amplifier stage with a differential input and a differential output, two current drain devices being connected to each one of the terminals of the differential output.

Limiting amplifier

A voltage controlled surface acoustic wave oscillator includes an integrated circuit and a two port resonator connected as a feedback element around the integrated circuit. The integrated circuit includes a phase shifting network and an amplifier directly connected to the phase shifting network.

Voltage controlled saw oscillator

The invention can be related to the technical field of implementation and control of electricity controllable active fibers. In accordance with the invention filters are controlled and implemented with the aid of a differential gain stage. Said stage includes pairs of like amplification components (Q.sub.I11 and Q.sub.I21, Q.sub.I12 and Q.sub.I22, Q.sub.I13 and Q.sub.I23), and groups of series-connected diode components as well as at least one current generator (Q1, Q2, Q3). The forward voltage drop of the diode components has the same current responsiveness as the base-emitter voltage of the amplification components. A filter of the first order includes a differential gain stage with a capacitive component (C) connected across the output of said stage or to its amplification components. A filter of the second order can include two differential gain stages, each with its capacitive component (C1, C2) in circuit. An oscillator for controlling filters can comprise three series-connected lowpass filters each including its differential gain stage.

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Weinfelden, Switzerland

Heinz B Mader