Patent US5285168A successfully refreshed from Google Patents.
US5285168A
Expired / Lapsed
US
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Operational amplifier for stably driving a low impedance load of low power consumption
Assignee: Hitachi Ltd
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Filing: 1992-09-15
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Granted: 1994-02-08
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Expires: 2012-09-15
Abstract
Abstract An operational amplifier is equipped at its input stage with a folded cascode type differential amplifier and at its downstream stage with pre-buffers, which include a differential amplification stage of PMOS input and a differential amplification stage of NMOS input, as level shifters. A MOS resistor having its gate terminal fed with an intermediate bias potential between a supply voltage V DD and an earth potential is connected between every one of the drain terminals of current-mirror connected load MOSFETs in the pre-buffers. As a result, the gains of the pre-buffers in the steady state can be suppressed to about 10 dB or less. The individual MOSFETs of the push-pull output stage are individually driven by the pre-buffers of low gains.
Inventors
- 👤 Takashi Tomatsu
- 👤 Takaaki Noda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:42
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/45; H03F3/45071; H03F3/45076; H03F3/45179; H03F3/45183; H03F3/45192; H03F3/30; H03F3/3001; H03F2203/00; H03F2203/30; H03F2203/30036; H03F2203/30096; H03F2203/30129; H03F2203/45; H03F2203/45028; H03F2203/45182; H03F2203/45281; H04; H04L; H04L25/00; H04L25/02; H04L25/0264; H04L25/028
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
96 words
An operational amplifier comprising: a differential input stage; a push-pull type output stage; and level shifting means for level-shifting the output of said differential input stage to transmit the level-shifted output to said push-pull type output stage, wherein said level shifting means includes: a first differential amplifier having a current mirror type load including a pair of P-channel type MOSFETs; and a second differential amplifier having a current mirror type load including a pair of N-channel type MOSFETs, and wherein a resistance element is connected between the drain terminals of each of said pairs of MOSFETs.
Claim 2
Dependent Claim
96 words
An operational amplifier comprising: a differential input stage; a push-pull type output stage; and level shifting means for level-shifting the output of said differential input stage to transmit the level-shifted output to said push-pull type output stage, wherein said level shifting means includes: a first differential amplifier having a current mirror type load including a pair of P-channel type MOSFETs; and a second differential amplifier having a current mirror type load including a pair of N-channel type MOSFETs, and wherein a resistance element is connected between the drain terminals of each of said pairs of MOSFETs.
Claim 3
Dependent Claim
15 words
An operational amplifier according to claim 1, wherein each said resistance element includes a MOSFET.
Claim 4
Dependent Claim
50 words
An operational amplifier according to claim 2, wherein the resistance element connected between the drain terminals of said pair of P-channel type MOSFETs is a P-channel type MOSFET, and wherein the resistance element connected between the drain terminals of said pair of N-channel type MOSFETs is an N-channel type MOSFET.
Claim 5
Dependent Claim
31 words
An operational amplifier according to claim 3, wherein the resistance element that is a P-channel type MOSFET has a higher resistance than the resistance element that is the N-channel type MOSFET.
Claim 6
Dependent Claim
49 words
An operational amplifier according to claim 4, wherein the resistance element that is P-channel type MOSFET has its gate terminal coupled to a first supply voltage terminal, and wherein the resistance element that is an N-channel type MOSFET has its gate terminal coupled to a second supply voltage terminal.
Claim 7
Dependent Claim
62 words
An operational amplifier according to claim 4, wherein the resistance element that is a P-channel type MOSFET and the resistance element that is an N-channel MOSFET have their gate terminals fed with an intermediate voltage between a positive supply voltage to be fed to said first supply voltage terminal and a ground voltage to be fed to said second supply voltage terminal.
Claim 8
Dependent Claim
31 words
An operational amplifier according to claim 6, wherein said P-channel type MOSFET and said N-channel type MOSFET constituting said resistance elements individually operate from an unsaturated range to a saturated range.
Claim 9
Dependent Claim
67 words
An operational amplifier according to claim 7, wherein said differential input stage is a folded cascode type differential amplifier including: a differential amplifier having an output; and amplification means having a current source for feeding a bias current, and a gate-grounded type MOSFET for receiving the bias current, for receiving the output of said differential amplifier at its source terminal, and for outputting from its drain terminal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-02-07 | 1997-08-09 | 1998-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-02-07 | 2001-08-09 | 2002-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-02-07 | 2005-08-09 | 2006-02-08 | $7700.00 | Window Closed / Lapsed |