Opto-electronic transconductors
AssigneeImperial College of Science, Technology and Medicine
InventorsChristofer Toumazou, Tongtod Vanisri
Life of this patent
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Abstract
A transconductance device particularly suitable for use as a high frequency active filter has an input stage including at least one field effect transistor (M.sub.1) arranged to drive a laser diode (LD.sub.1) and an output stage including at least one photodiode (PD.sub.1) optically coupled to the laser diode. The output stage is preferably provided with a high impedance bias current supply circuit. In an alternative arrangement particularly useful as an operational amplifier, a differential input stage includes a pair of laser diodes (LD.sub.1 and LD.sub.2) optically coupled to respective photodiodes (PD.sub.1 and PD.sub.2) connected in series, the output being taken from the junction of the two photodiodes.
Claims18
A transconductance device comprising:
- an input stage including at least one field effect transistor (M.sub.1) arranged to drive a laser diode (LD.sub.1);
- and,
- an output stage comprising a first photodiode (PD.sub.1) optically coupled to the laser diode, the output stage having a high impedance bias current supply circuit which comprises a second photodiode (PD.sub.2) connected in series with the first photodiode (PD.sub.1) and optically coupled to a further light source having a constant output.
A transconductance device comprising:
- an input stage including a differential amplifier having a pair of field effect input transistors (M.sub.1, M.sub.2) each driving a laser diode (LD.sub.1, LD.sub.2);
- and,
- an output stage comprising a pair of photodiodes (PD.sub.1, PD.sub.2) connected in series, each photodiode being optically coupled to one of the laser diodes (LD.sub.1, LD.sub.2), an output signal being taken from a junction of said photodiodes.
An opto-electronic inductor comprising:
- a first non-inverting transconductor;
- and,
- a second inverting transconductor connected as an integrator with a grounded load and arranged in a back-to-back relationship with said first non-inverting transconductor, at least one of the first transconductor and the second transconductor including a transconductance device comprising:
- an input stage including at least one field effect transistor (M.sub.1) arranged to drive a laser diode (D.sub.1), and
- an output stage comprising a first photodiode (PD.sub.1) optically coupled to the laser diode, the output stage having a high impedance bias current supply circuit which comprises a second photodiode (PD.sub.2) connected in series with the first photodiode (PD.sub.1) and optically coupled to a further light source having a constant output.
A transconductance device comprising:
- an input stage including at least one field effect transistor arranged for driving a laser diode;
- and,
- an output stage including a first photodiode optically coupled to the laser diode, the output stage having a high impedance bias current supply circuit including a second photodiode.
A transconductance device comprising:
- an input stage including at least one field effect transistor arranged to drive a laser diode;
- an output stage comprising a first photodiode optically coupled to the laser diode;
- and,
- a high impedance bias current supply circuit comprising a second photodiode connected in series with the first photodiode and optically coupled to a further light source having a constant output.
Dependencies are inferred from the claim text.