Pulse or digital communications – Repeaters – Testing
Patent
1989-08-08
1993-10-26
Safourek, Benedict V.
Pulse or digital communications
Repeaters
Testing
330293, 330306, 359189, 375 75, H04B 1006
Patent
active
052572854
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a transimpedance pre-amplifier circuit and to a receiver circuit incorporating the pre-amplifier circuit.
The circuits are particularly intended for receiving and amplifying digital signals at high frequencies. For example, the circuits can be used in optical transmission systems at frequencies above 1 GHz.
The traditional approach to receiver design involves the use of a front end whose idealised response shows a simple roll-off of amplitude with increasing frequency, which requires the following receiver stages to have very wide bandwidth. In order to avoid high frequency is instability, traditionally designed receivers incorporate a dedicated passive filter. Using discrete components, it is possible to fabricate suitable wide bandwidth circuits, but the concomitant disadvantages of large size and high cost conspire against the widespread adoption of such hybrid circuits in telecommunications systems.
In an ideal receiver for a digital transmission system, the object is to ensure that at the receiver decision point (where the nature of a received bit is determined) the spectrum is of raised cosine form. The effect of having a raised cosine spectrum is to ensure finite bit length such that during determination of a particular bit the immediately preceding bit contributes nothing. In traditional receiver design, a raised cosine response is not directly realisable, but reasonable approximations can be achieved. If the receiver pre-amplifier has a single pole response, as is usual, a close approximation to a raised cosine is obtained by combining this with a 3 pole maximally flat Butterworth filter. There are several significant disadvantages to this approach: first, if the pre-amplifier has a bandwidth of 0.6 times the system bit rate (B), and the Butterworth filter has a bandwidth of 0.7B, as is usual, the remaining amplifier stages need a bandwidth much greater than B in order for the receiver as a whole to satisfy the Nyquist requirement. The provision of suitable wide bandwidth amplifiers is expensive, technically demanding and leads to excessive power dissipation. In addition to such amplifiers being difficult to implement as integrated circuits, the Butterworth filter, which routinely comprises an inductor and a pair of capacitors, is also difficult to realise as part of an integrated circuit.
Unfortunately, in integrated circuit technology, a large bandwidth is generally only realisable at the cost of increased power dissipation, because parastic capacitance, etc., become increasingly important as the feature size is reduced in order to achieve large bandwidth performance. As a result, high bit rate (2.4 GBit and above) receivers have thus far been produced with only very limited levels of integration ("low functionality").
An example of a "state-of-the-art" 2.4 Gb/s receiver is that described by Y. Hatta et al of Hitachi, at the recent IEEE GaAs IC Symposium 1988. The Hatta receiver comprises a set of seven GaAs chips, three of which are amplifiers. The three amplifier chips each has an output buffer with peaking capability to improve frequency response, although this wastes power. The transimpedance pre-amplifier has a bandwidth of 2.4 GHz, the two subsequent amplifier stages having bandwidths of 2.9 and 2.8 GHz respectively.
The present invention provides a pre-amplifier circuit which can be "tailored" in accordance with the overall requirements of the receiver to enable less stringent demands to be made on the component stages of the receiver circuit. This enables the invention to avoid high frequency instability and to meet the design criteria even at very high frequencies and even where the receiver is to be fabricated on integrated circuits.
According to a first aspect of the present invention there is provided a transimpedance pre-amplifier circuit comprising a first transistor amplifier stage having an input and an output, and feedback means coupling the output to the input, and further comprising a load including a reactive element connected to the output of
REFERENCES:
patent: 3036224 (1962-05-01), Abraham
patent: 3356959 (1967-12-01), Vilkomerson
patent: 3436670 (1969-04-01), Solomon
patent: 3436675 (1966-12-01), Lunau
patent: 3707685 (1972-12-01), Geffe
patent: 3849744 (1974-11-01), Furuya
patent: 3863173 (1975-01-01), Scheib et al.
patent: 3899743 (1975-08-01), Csicatka
patent: 4420724 (1983-12-01), Owen
patent: 4694504 (1987-09-01), Porter et al.
Electronics Letters, vol. 19, No. 14, Nov. 24, 1983, O. Wada et al., "Monolithic PIN/Preamplifier Circuit Integrated, etc.", pp. 1031-1032.
Electronics Letters, vol. 20, No. 20, Sep. 27, 1984, Walker et al., "Ge APD/GaAs FET/OP-AMP transimpedance optical, etc.", pp. 808-809.
1978 IEEE International Solid-State Circuits Conference, Feb. 15, 1978, R. L. Van Tuyl, "a monolithic integrated 4-GHz amplifier", p. 72.
IEEE Transactions on Communications, Oct. 1976, J. L. Hullett, "A Feedback Receiver Amplifier for Optical Transmission Systems", pp. 1180-1185.
GaAs I.C. Symposium 1988, Hatta et al, "A GaAs IC set for full integration of 2.4 Gbit/s optical transmission systems", pp. 15-18.
Proceedings of the IREE Aust., Sep. 1979, Hullett, "Optical Communications Receivers", pp. 127-136.
IEEE Journal of Solid State Circuits', vol. SC-21, No. 6, Dec. 1986 pp. 909-915.
BT&D Technologies Limited
Safourek Benedict V.
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