Ultrawide-bandwidth low-noise optical receiver

• US 5,010,588 A
• Filed: 03/06/1989
• Issued: 04/23/1991
• Est. Priority Date: 03/10/1988
• Status: Expired due to Term

• Current Assignee: TTI Inventions A LLC (Intellectual Ventures LLC)
• Original Assignee: Bell Communications Research, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Gimlett, James L.
• Primary Examiner(s): Orsino, Joseph A.
• Assistant Examiner(s): PASCAL, LESLIE C
• Application Number:
  US07/318,844
• Time in Patent Office: 778 Days
• Field of Search: 455/606, 455/607, 455/617, 455/619, 330/59, 330/176, 330/302-303, 330/307-308, 330/310-311, 330/227
• US Class Current: 398/202
• CPC Class Codes: H03F 3/08 controlled by light
• CPC Class Codes: H04B 10/6932 Bandwidth control of bit rate adaptation

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.

Claims

1. An optical receiver having a bandwidth that extends from near dc to the multi-gigahertz range for converting a received optical signal to an amplified electrical signal at the output of the receiver, said receiver comprising:

photodetector means for converting the received optical signal to a proportional low-level electrical signal,

inductive/resistive frequency enhancement means connected to said photodetector means for extending the high frequency response of a first stage of an amplifying means and for providing a high input impedance to said first stage,

said amplifying means being connected between said frequency enhancement means and said receiver output and comprising a plurality of amplifying stages each comprising a transistor amplifier and a microwave matching circuit comprising a modified T-network having as series-arm impedances inductive elements and as a shunt-leg impedance a microwave element in series with a resistor, said amplifying stages providing individual input and output impedances decreasing successively from said high input impedance at said first of said stages to a low output impedance at the last of said stages, the resistor in the shunt-leg of each modified T-network being chosen to extend the bandwidth of each stage to near the dc level and the values of said inductive and microwave elements being chosen to preserve the high frequency response as extended by said frequency enhancement means.

2. An optical receiver in accordance with claim 1 wherein the transistor amplifier in each of said amplifying stages is an FET or an HEMT.

3. An optical receiver in accordance with claim 1 wherein said frequency enhancement means comprises an inductive peaking means.

4. An optical receiver in accordance with claim 3 wherein said inductive peaking means comprises a microstrip transmission line in series with wire bonds at its input and output.

5. An optical receiver in accordance with claim 4 wherein the microwave elements in the modified T-networks are microstrip transmission lines.

6. An optical receiver in accordance with claim 1 wherein said frequency enhancement means comprises a modified T-network having as series-arm impedances inductive elements and as a shunt-leg impedance a microwave element in series with a resistor.

7. An optical receiver in accordance with claim 6 wherein the inductive element in each modified T-network is a wire bond.

8. An optical receiver in accordance with claim 7 wherein the microwave element in each modified T-network is a coplanar waveguide.

9. An optical receiver having a bandwidth that extends from near dc to the multi-gigahertz range for converting a received optical signal to an amplified electrical signal at the output of the receiver comprising:

photodetector means for converting the received optical signal to a proportional low-level electrical signal,

inductive/resistive frequency enhancement means connected to said photodetector means for extending the high frequency response of a first amplifying stage and for providing a high input impedance to said first amplifying stage,

said first amplifying stage having said high input impedance and an intermediate output impedance for amplifying the enhanced low-level electrical signal, said first amplifying stage comprising a first transistor amplifier and a first output microwave matching circuit for providing said intermediate impedance, said first output microwave matching circuit comprising a modified T-network having a series-arm impedances inductive elements and as a shunt-leg impedance a microwave element in series with a resistor,

a second amplifying stage cascaded with said first stage having an intermediate input impedance and an intermediate output impedance for further amplifying the enchanced low-level electrical signal amplified by said first amplifying stage, said second amplifying stage comprising a second transistor amplifier and a second output microwave matching circuit for providing said intermediate impedance, said second output microwave matching circuit comprising a modified T-network having as series-arm impedances inductive elements and as a shunt-leg impedance a microwave element in series with a resistor, and

a third amplifying stage cascaded with said first and second stages having an intermediate input impedance and a low output impedance at the receiver output for providing an impedance transform to the amplified enchanced electrical signal, said third amplifying stage comprising a third transistor amplifier and a third output microwave matching circuit for providing said low output impedance, said third amplifying stage comprising a third transistor amplifier and a third output microwave matching circuit for providing said low impedance, said third output microwave matching circuit comprising a modified T-network having as series-arm impedances inductive elements and as a shunt-leg impedance a microwave element in series with a resistor,

the resistor in each of said modified T-networks being chosen to extend the bandwidth of each stage to near the dc level and the inductive and microwave elements in each of said modified T-networks being chosen to preserve the high frequency response of each stage as extended by said frequency enhancement means.

10. An optical receiver in accordance with claim 9 wherein said transistor amplifiers in said first, second and third amplifying stages are FETs or HEMTs.

11. An optical receiver in accordance with claim 9 wherein said frequency enhancement means comprises inductive peaking means.

12. An optical receiver in accordance with claim 11 wherein said inductive peaking means comprises a microstrip transmission line in series with wire bonds at its input and output.

13. An optical receiver in accordance with claim 12 wherein the microwave elements in each of said modified T-networks is a microstrip transmission line.

14. An optical receiver in accordance with claim 9 wherein said frequency enhancement means is a modified T-network having as series-arm impedances inductive elements and as a shunt-leg impedance a microwave element in series with a resistor.

15. An optical receiver in accordance with claim 14 wherein the inductive elements in each modified T-network is a wire bond.

16. An optical receiver in accordance with claim 15 wherein the microwave element in each modified T-network is a coplanar waveguide.