US4888562A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low noise, high speed current or voltage amplifier
Assignee: National Semiconductor Corp
•
Filing: 1987-09-09
•
Granted: 1989-12-19
•
Expires: 2007-09-09
Abstract
Abstract A low noise, high speed current transimpedance amplifier system (20) includes AC bootstrapping for the photodiode D1 by capacitor C2 connected between the source of the JFET Q1 and the cathode of the photodiode D1 by line (56). Line (58) also provides AC bootstrapping to the case of the module (40) through capacitor C2. Similarly, the source resistor R3 and drain of JFET Q1 are AC bootstrapped through capacitors C1 and C4 to the emitters of the transistors Q2 and Q4 by lines (60) and (62). The collectors of the second stage transistors Q2 and Q4 are bootstrapped to the third stage transistor Q3 emitter through capacitor C8 by line (64). This bootstrapping reduces the effective input capacitance at the front end of the amplifier system (20) by a factor of up to about 100, thus reducing signal noise component in the subsequent stage or stages to negligible compared to front end noise.
Inventors
- 👤 Peter A. Edler
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:53
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/08; H03F1/14; H03F3/00; H03F3/04; H03F3/08; H03F3/082; H03F2200/00; H03F2200/261
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
152 words
An amplifier system, which comprises a front end transistor having a control electrode, an input current flow electrode and an output current flow electrode, first coupling means for alternating current coupling the output current flow electrode of said front end transistor to at least one contributor of an effective input capacitance of said amplifier system to reduce the effective input capacitance of said amplifier system, a second stage transistor coupled to said front end transistor having a control electrode, an input current flow electrode and an output current flow electrode, second coupling means for coupling the output current flow electrode of said front end transistor to the control electrode of said second stage transistor, and third coupling means for alternating current coupling the output current flow electrode of said second stage transistor to the input current flow electrode of said front end transistor to reduce the effective input capacitance of said amplifier.
Claim 2
Dependent Claim
152 words
An amplifier system, which comprises a front end transistor having a control electrode, an input current flow electrode and an output current flow electrode, first coupling means for alternating current coupling the output current flow electrode of said front end transistor to at least one contributor of an effective input capacitance of said amplifier system to reduce the effective input capacitance of said amplifier system, a second stage transistor coupled to said front end transistor having a control electrode, an input current flow electrode and an output current flow electrode, second coupling means for coupling the output current flow electrode of said front end transistor to the control electrode of said second stage transistor, and third coupling means for alternating current coupling the output current flow electrode of said second stage transistor to the input current flow electrode of said front end transistor to reduce the effective input capacitance of said amplifier.
Claim 3
Dependent Claim
88 words
The amplifier system of claim 1 additionally comprising a third stage transistor coupled to said second stage transistor having a control electrode and two current flow electrodes, means for coupling the control electrode of said third stage transistor to the output current flow electrode of the second stage transistor, and means for alternating current coupling the output current flow electrode of said third stage transistor to the input current flow electrode of said front end or second transistor to reduce the effective input capacitance of said amplifier system.
Claim 4
Dependent Claim
27 words
The amplifier system of claim 2 in which said front end transistor comprises a field effect transistor and said second and third stage transistors comprise bipolar transistors.
Claim 5
Dependent Claim
21 words
The amplifier system of claim 1 additionally comprising an additional second stage transistor connected in parallel with said second stage transistor.
Claim 6
Dependent Claim
26 words
The amplifier system of claim 1 in which said front end transistor comprises a field effect transistor and said second stage transistor comprises a bipolar transistor.
Claim 7
Dependent Claim
61 words
The amplifier system of claim 1 in which said amplifier system additionally includes a source of an input signal connected to the control electrode of said front end transistor, and in which the input signal provided by said source is a current waveform and said amplifier system is configured to provide a voltage waveform at the output of said amplifier system.
Claim 8
Dependent Claim
17 words
The amplifier system of claim 6 in which said source of an input signal is a photodiode.
Claim 9
Dependent Claim
43 words
The amplifier system of claim 7 in which said first coupling means alternating current couples the output current flow electrode of said front end transistor to an electrode of said photodiode as a contributor to the effective input capacitance of said amplifier system.
Claim 10
Dependent Claim
59 words
The amplifier system of claim 8 in which at least one of said front end transistor and said photodiode are provided in a case, said system further including means for alternating current coupling the output current flow electrode of said front end transistor additionally to said case as a contributor to the effective input capacitance of said amplifier system.
Claim 11
Dependent Claim
24 words
The amplifier system of claim 9 in which said front end transistor and said photodiode are provided as a hybrid circuit in said case.
Claim 12
Dependent Claim
25 words
The amplifier system of claim 1 additionally comprising a resistive and capacitive network compensation circuit connected to receive an output signal from said amplifier system.
Claim 13
Dependent Claim
24 words
The amplifier system of claim 11 additionally comprising a diode connected to supply the output signal from said amplifier system to said compensation circuit.
Claim 14
Dependent Claim
92 words
The amplifier system of claim 1 additionally comprising a first operational amplifier coupled to said second stage transistor with an input coupled to receive an output signal from said second stage transistor, a second operational amplifier coupled to said first operational amplifier with an input coupled to receive an output signal from said first operational amplifier, a first video clamping diode circuit connected between said first operational amplifier and the input of said second operational amplifier, and a second video clamping diode circuit coupled to an output of said second operational amplifier.
Claim 15
Dependent Claim
24 words
The amplifier system of claim 1 in which at least one of said first coupling means and said third coupling means includes a capacitor.
Claim 16
Dependent Claim
52 words
The amplifier system of claim 1 including a sequence of coupled stage transistors, a bias element coupled to the input or output current flow electrode of one of said stage transistors, and means for alternating current coupling said bias element to the output electrode of a subsequent one of said stage transistors.
Claim 17
Dependent Claim
38 words
The amplifier system of claim 15 including a bias resistor coupled to the output current flow electrode of said front end transistor, and means for coupling the output electrode of said second stage transistor to said bias resistor.
Claim 18
Dependent Claim
23 words
The amplifier system of claim 1 in which said front end transistor is connected as an amplifier having a substantially unit voltage gain.
Claim 19
Dependent Claim
23 words
The amplifier system of claim 17 in which said second stage transistor is connected as an amplifier having a substantially unity voltage gain.
Claim 20
Dependent Claim
24 words
The amplifier system of claim 17 in which said second stage transistor is connected as an amplifier having a greater than unity voltage gain.
Claim 21
Dependent Claim
68 words
The amplifier system of claim 1 in which said amplifier system additionally includes a source of an input signal connected to the control electrode of said front end transistor, a case which houses said source of an input signal, and means for alternating current coupling said front end transistor to the case of said source of an input signal to reduce the effective input capacitance of said amplifier.
Claim 22
Dependent Claim
46 words
The amplifier system of claim 1 including a case which houses said front end transistor, and means for alternating current coupling the signal output of said front end transistor to the case of said front end transistor to reduce the effective input capacitance of said amplifier.
Claim 23
Dependent Claim
142 words
An amplifier system, which comprises a first amplifier having a control input, a current flow input and a current flow output, first coupling means for alternating current coupling the current flow output of said first amplifier to at least one contributor of an effective input capacitance of said amplifier system to reduce the effective input capacitance of said amplifier system, a second amplifier coupled to said first amplifier having a control input, a current flow input and a current flow output, second coupling means for coupling the current flow output of said first amplifier to the control input of said second amplifier, and third coupling means for alternating current coupling the current flow output of said second amplifier to at least one contributor of an effective input capacitance of said first amplifier to reduce the effective input capacitance of said amplifier system.
Claim 24
Dependent Claim
142 words
An amplifier system, which comprises a first amplifier having a control input, a current flow input and a current flow output, first coupling means for alternating current coupling the current flow output of said first amplifier to at least one contributor of an effective input capacitance of said amplifier system to reduce the effective input capacitance of said amplifier system, a second amplifier coupled to said first amplifier having a control input, a current flow input and a current flow output, second coupling means for coupling the current flow output of said first amplifier to the control input of said second amplifier, and third coupling means for alternating current coupling the current flow output of said second amplifier to at least one contributor of an effective input capacitance of said first amplifier to reduce the effective input capacitance of said amplifier system.
Claim 25
Dependent Claim
87 words
The amplifier system of claim 22 additionally comprising a third amplifier coupled to said second amplifier having a control input, a current flow input and a current flow output, means for coupling the control input of said third amplifier to the current flow output of the second amplifier, means for alternating current coupling the current flow output of said third amplifier to at least one contributor of an effective input capacitance of said first or second amplifier to reduce the effective input capacitance of said amplifier system.
Claim 26
Dependent Claim
64 words
The amplifier system of claim 22 in which said amplifier system additionally includes a source of an input signal connected to the control input of said first amplifier, and in which the input signal provided by said source of an input signal is a current waveform and said amplifier system is configured to provide a voltage waveform at the output of said amplifier system.
Claim 27
Dependent Claim
17 words
The amplifier system of claim 24 in which said source of an input signal comprises a photodiode.
Claim 28
Dependent Claim
37 words
The amplifier system of claim 25 including means for coupling the output current flow electrode of said first amplifier to an electrode of said photodiode as a contributor to the effective input capacitance of said amplifier system.
Claim 29
Dependent Claim
56 words
The amplifier system of claim 25 in which at least one amplifier and said photodiode are provided in a case, said amplifier system further including means for alternating current coupling the output current flow electrode of said front end transistor additionally to said case as a contributor to the effective input capacitance of said amplifier system.
Claim 30
Dependent Claim
23 words
The amplifier system of claim 27 in which said first amplifier and said photodiode are provided as a hybrid circuit in a case.
Claim 31
Dependent Claim
25 words
The amplifier system of claim 22 additionally comprising a resistive and capacitive network compensation circuit connected to receive an output signal from said amplifier system.
Claim 32
Dependent Claim
23 words
The amplifier system of claim 29 comprising a diode connected to supply the output signal from said amplifier system to said compensation circuit.
Claim 33
Dependent Claim
90 words
The amplifier system of claim 22 additionally comprising a first operational amplifier coupled to said second amplifier with an input coupled to receive an output signal from said second amplifier, a second operational amplifier coupled to said first operational amplifier with an input coupled to receive an output signal from said first operational amplifier, a first video clamping diode circuit connected between said first operational amplifier and the input of said second operational amplifier, and a second video clamping diode circuit coupled to an output of said second operational amplifier.
Claim 34
Dependent Claim
46 words
The amplifier system of claim 22 including a bias impedance coupled to the current flow output of said first amplifier, and means for coupling the current flow output of said second amplifier to said bias impedance to reduce the effective input capacitance of said amplifier system.
Claim 35
Dependent Claim
24 words
The amplifier system of claim 22 in which at least one of said first coupling means and said third coupling means includes a capacitor.
Claim 36
Dependent Claim
29 words
The amplifier system of claim 22 in which at least one of said first and second amplifiers additionally has a transistor connected in common collector or common drain configuration.
Claim 37
Dependent Claim
31 words
The amplifier system of claim 34 in which said first amplifier has said transistor connected in common drain configuration and said second amplifier has said transistor connected in common collector configuration.
Claim 38
Dependent Claim
129 words
An amplifier system comprising: a first amplifier having a control input, a signal input and a signal output, coupling means for alternating current coupling the signal output of said first amplifier to at least one contributor of an effective input capacitance of said amplifier to reduce the effective input capacitance of said amplifier; and a second amplifier coupled to said signal output of said first amplifier; said first amplifier having a voltage gain of unity and said second amplifier having a voltage gain greater than unit; at least one of said first amplifier and said second amplifier packaged in a case, said amplifier system including means for alternating current coupling the signal output of said amplifier to said case to reduce the effective input capacitance of said amplifier system.
Claim 39
Dependent Claim
129 words
An amplifier system comprising: a first amplifier having a control input, a signal input and a signal output, coupling means for alternating current coupling the signal output of said first amplifier to at least one contributor of an effective input capacitance of said amplifier to reduce the effective input capacitance of said amplifier; and a second amplifier coupled to said signal output of said first amplifier; said first amplifier having a voltage gain of unity and said second amplifier having a voltage gain greater than unit; at least one of said first amplifier and said second amplifier packaged in a case, said amplifier system including means for alternating current coupling the signal output of said amplifier to said case to reduce the effective input capacitance of said amplifier system.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-12-18 | 1993-06-19 | 1993-12-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-12-18 | 1997-06-19 | 1997-12-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-12-18 | 2001-06-19 | 2001-12-19 | $7700.00 | Window Closed / Lapsed |