US4237425A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic bias adjusting circuit
Assignee: Individual
•
Filing: 1979-05-03
•
Granted: 1980-12-02
•
Expires: 1999-05-03
Abstract
Abstract A bias adjusting circuit for a push-pull amplifier is disclosed, which automatically increases or decreases the bias in the amplifier circuit so that the desired bias level is maintained. The bias adjusting circuit measures the current consumption of both halves of the push-pull amplifier, determines the point at which output current zero crossings have occurred, and at these times makes any necessary changes to the bias current to conform to a desired level. The circuit has an insignificant effect on the amplifier's power efficiency, and offers a degree of bias stability unattainable with conventional techniques.
Inventors
- 👤 David A. Spiegel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 01:52
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/30; H03F3/3069; H03F3/3071; H03F1/00; H03F1/30; H03F1/307; H03F1/32; H03F1/3205; H03F3/3001; H03F3/301; H03F3/3016; H03F3/3076; H03F3/3077
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
73 words
A circuit for automatic bias adjustment of a push-pull amplifier comprising: a. current measuring means for comparing the current consumed by each half of said push-pull amplifier with a predetermined current level; b. logic means for generating a control signal depending upon the input to said current measuring means; c. means for integrating the control signals of said logic means, and d. bias control means connected to the output of said integrating means.
Claim 2
Dependent Claim
73 words
A circuit for automatic bias adjustment of a push-pull amplifier comprising: a. current measuring means for comparing the current consumed by each half of said push-pull amplifier with a predetermined current level; b. logic means for generating a control signal depending upon the input to said current measuring means; c. means for integrating the control signals of said logic means, and d. bias control means connected to the output of said integrating means.
Claim 3
Dependent Claim
12 words
The circuit of claim 1, wherein said integrating means comprises a capacitor.
Claim 4
Dependent Claim
24 words
The circuit of claim 1, wherein said integrating means comprises an operational amplifier with an integrating capacitor connected between its output and inverting input.
Claim 5
Dependent Claim
20 words
The circuit of claim 1, wherein said integrating means comprises a digital up-down counter and a digital to analog converter.
Claim 6
Dependent Claim
27 words
The circuit of claim 1, wherein said logic means comprises two equal and opposite current sources whose current paths are determined by a pair of relay equivalents.
Claim 7
Dependent Claim
13 words
The circuit of claim 5, wherein said relay equivalents comprise electronic differential amplifiers.
Claim 8
Dependent Claim
14 words
The circuit of claim 6, wherein said differential amplifiers comprise a pair of transistors.
Claim 9
Dependent Claim
22 words
The circuit of claim 7, further comprising an additional amplification stage connected in cascade with at least one of said differential amplifiers.
Claim 10
Dependent Claim
18 words
The circuit of claim 5, further comprising feedback means for equalizing the currents in said opposing current sources.
Claim 11
Dependent Claim
27 words
The circuit of claim 1, wherein said logic means comprises an electronic gating circuit, said gating circuit being connected between said current measuring and said integrating means.
Claim 12
Dependent Claim
26 words
The circuit of claim 1, wherein said current measuring means comprises a Hall sensor adapted for measuring the flow of output current through said push-pull amplifier.
Claim 13
Dependent Claim
32 words
The circuit of claim 1, wherein said current measuring means comprises at least one resistor connected between the power supply input of both sides of the output stage and the power supply.
Claim 14
Dependent Claim
49 words
The circuit of claim 1, wherein said bias control means comprises a light-emitting diode connected to said integrating means, a phototransistor positioned for actuation by said light-emitting diode, and means for connecting the output of said phototransistor to said push-pull amplifier in a way that will control bias levels.
Claim 15
Dependent Claim
33 words
The circuit of claim 1, wherein said bias control means comprises a voltage-to-current converting circuit to change the bias control voltage into a current which is amplified to control the output bias level.
Claim 16
Dependent Claim
115 words
A circuit for automatic bias adjustment of a push-pull amplifier comprising: a. first and second differential amplifiers, wherein the inputs of said first differential amplifier are connected to a voltage reference and a current sensing resistor, wherein the inputs of said second differential amplifier are connected to a negative voltage reference and a current sensing resistor; b. logic means comprising two equal and opposite current sources whose current flow is directed by said differential amplifiers; c. integrating means connected to the output of said logic means; and d. bias control means for connecting the output of said integrating means to said push-pull amplifier in a way that will control the amount of output bias current.
Claim 17
Dependent Claim
115 words
A circuit for automatic bias adjustment of a push-pull amplifier comprising: a. first and second differential amplifiers, wherein the inputs of said first differential amplifier are connected to a voltage reference and a current sensing resistor, wherein the inputs of said second differential amplifier are connected to a negative voltage reference and a current sensing resistor; b. logic means comprising two equal and opposite current sources whose current flow is directed by said differential amplifiers; c. integrating means connected to the output of said logic means; and d. bias control means for connecting the output of said integrating means to said push-pull amplifier in a way that will control the amount of output bias current.
Claim 18
Dependent Claim
12 words
The circuit of claim 15, wherein said integrating means comprises a capacitor.
Claim 19
Dependent Claim
23 words
The circuit of claim 15, wherein said integrating means comprises an operational amplifier with a capacitor connected between its output and inverting input.
Claim 20
Dependent Claim
16 words
The circuit of claim 15, further comprising feedback means for equalizing said two opposing current sources.
Claim 21
Dependent Claim
26 words
The circuit of claim 15, wherein said bias control means consists of a light-emitting diode optically coupled to a phototransistor which controls output bias current levels.
Claim 22
Dependent Claim
49 words
The circuit of claim 15, wherein said bias control means comprises means for converting the bias control voltage into one or more bias control currents, and means for using this current to control the operating point of driver transistors which directly control bias current levels of the output devices.
Claim 23
Dependent Claim
92 words
A circuit for automatic bias adjustment of a push-pull amplifier comprising: a. a pair of Hall sensors for measuring the current consumption of both halves of the push-pull output stage; b. an electronic gating circuit, wherein the outputs of said Hall sensors are the inputs to said gating circuit; c. a digital integrating means connected to the outputs of said gating circuit; and d. a bias control means connected to the output of said integrating means whereby the bias level of said amplifier is controlled by the output of said integrating means.
Claim 24
Dependent Claim
92 words
A circuit for automatic bias adjustment of a push-pull amplifier comprising: a. a pair of Hall sensors for measuring the current consumption of both halves of the push-pull output stage; b. an electronic gating circuit, wherein the outputs of said Hall sensors are the inputs to said gating circuit; c. a digital integrating means connected to the outputs of said gating circuit; and d. a bias control means connected to the output of said integrating means whereby the bias level of said amplifier is controlled by the output of said integrating means.
Claim 25
Dependent Claim
18 words
The circuit of claim 21, wherein said integrating means comprises an electronic counter and digital to analog converter.
Claim 26
Dependent Claim
19 words
The circuit of claim 22, further comprising an electronic latch between said digital counter and digital to analog converter.
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) | 1983-12-02 | 1984-06-02 | 1984-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-02 | 1988-06-02 | 1988-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-02 | 1992-06-02 | 1992-12-02 | $7700.00 | Window Closed / Lapsed |