Patent EP0451378A1 successfully refreshed from Google Patents.
EP0451378A1
Expired / Lapsed
EP
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FET amplifying circuits and methods of operation
Assignee: Hewlett Packard Ltd
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Filing: 1990-04-10
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Granted: —
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Expires: 2010-04-10
Abstract
Abstract An amplification circuit is disclosed which comprises a differential stage employing field effect transistors (30, 31). The FET devices are source coupled and the bias voltage on the drain electrodes is arranged to vary according to the magnitude of the current being switched. This has been found to reduce the problem of negative overshoot. Also disclosed is a technique for optimising the operation of an amplification circuit comprising a number of differential stages.
Inventors
- 👤 John Rodney Pottinger
- 👤 Daya Rasaratnam
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 10:15
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/04; H03K17/041; H03K17/04106; H03F; H03F3/00; H03F3/45; H03F3/45071; H03F3/45076; H03F3/45376; H03F3/45381; H03F3/45385; H03K17/12; H03K17/16; H03K17/161; H03K17/162; H03K5/00; H03K5/22; H03K5/24; H03K5/2472; H03K5/2481
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
43 words
A differential type amplification circuit comprising a pair of FET devices whose source electrodes are coupled characterised in that the bias voltage on the drain electrodes of the FET devices is arranged to vary according to the magnitude of the current being switched.
Claim 2
Dependent Claim
21 words
A differential type amplification circuit according to claim 1, including a tail FET to which a bias signal can be applied.
Claim 3
Dependent Claim
22 words
A differential type amplification circuit according to claim 1 or claim 2, and comprising a plurality of said pairs of FET device.
Claim 4
Dependent Claim
54 words
A circuit comprising a plurality of stages at least some of which are made up of differential FET pairs wherein the a parameter of the final differential stage is sensed and one or more parameters of the stages are adjusted to set said levels at selected values to optimise the operation of the circuit.
Claim 5
Dependent Claim
23 words
A circuit according to claim 4, wherein said parameters are selected such that the output switching stage is overdriven by a defined amount.
Claim 6
Dependent Claim
30 words
A circuit according to claim 4 or claim 5, wherein said sensed parameter of the final differential stage is the output level or the measured output switching speed or both.
Claim 7
Dependent Claim
35 words
A circuit according to any one of claims 4 to 6, wherein at least some of said stages each comprise a differential type amplification circuit in accordance with any one of claims 1 to 3.
Claim 8
Dependent Claim
26 words
A circuit according to any one of claims 4 to 7, wherein the parameters which are adjusted include currents applied to the tails of said stages.
Claim 9
Dependent Claim
27 words
A circuit according to any one of claims 4 to 8, including a cascode stage and a circuit for detecting the output levels of the cascode stage.
Claim 10
Independent Claim
50 words
A method of operating a differential type amplification circuit which includes a pair of FET devices comprising varying the voltage on the drain electrodes of the FET devices in accordance with the magnitude of current being switched in such a way as to minimise negative overshoot in the output waveform.
Claim 11
Independent Claim
52 words
A method of optimising operation of an amplification circuit which comprises a plurality of stages at least some of which are made up of differential FET pairs, the method comprising adjusting selected parameters of at least some of the stages such that the output switching stage is overdriven by a defined amount.
Claim 12
Dependent Claim
20 words
A method according to claim 11, wherein such parameters include the tail currents of one or more of said stages.
References Cited (Backward Citations)
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