Patent US4363004A successfully refreshed from Google Patents.
US4363004A
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Combining and filter circuit for a phase locked loop
Assignee: Ericsson Inc
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Filing: 1980-10-20
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Granted: 1982-12-07
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Expires: 2000-10-20
Abstract
Abstract A combining and filter circuit is provided to connect the acquisition circuit and phase detector circuit to the voltage controlled oscillator in a phase locked loop. The combining and filter circuit includes twin-T filters for removing reference frequency signals. An output circuit includes series resistors and capacitors, and reverse poled Schottky diodes which provide rapidly changing acquisition signals that are relatively noise free.
Inventors
- 👤 Arvid E. Englund, Jr.
- 👤 Gregory N. Mears
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:37
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/08; H03L7/10; H03L7/085; H03L7/093
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
105 words
An improved combining and filter circuit for use in a phase locked loop comprising: a. a first input for phase detector signals; b. a second input for acquisition circuit signals; c. first means for connecting said first and second inputs together; d. an output for control signals; e. second means including a first pair of diodes for connecting said first means to said output; f. a resistor and a first capacitor connected in series across said output; g. a second capacitor connected in parallel with said resistor; h. and a second pair of diodes each connected in parallel with said resistor in reverse poled directions.
Claim 2
Dependent Claim
105 words
An improved combining and filter circuit for use in a phase locked loop comprising: a. a first input for phase detector signals; b. a second input for acquisition circuit signals; c. first means for connecting said first and second inputs together; d. an output for control signals; e. second means including a first pair of diodes for connecting said first means to said output; f. a resistor and a first capacitor connected in series across said output; g. a second capacitor connected in parallel with said resistor; h. and a second pair of diodes each connected in parallel with said resistor in reverse poled directions.
Claim 3
Dependent Claim
16 words
The improved circuit of claim 1 wherein said second pair of diodes are the Schottky type.
Claim 4
Dependent Claim
17 words
The improved circuit of claim 1 or claim 2 wherein said second means include a twin-T filter.
Claim 5
Dependent Claim
17 words
The improved circuit of claim 1 or claim 2 wherein said first means include a twin-T filter.
Claim 6
Dependent Claim
14 words
The improved circuit of claim 3 wherein said first means include a twin-T filter.
Claim 7
Dependent Claim
148 words
An improved circuit for connecting a phase detector and an acquisition circuit to a voltage controlled oscillator in a phase locked loop comprising: a. a first input terminal for connection to said phase detector; b. a second input terminal of connection to said acquisition circuit; c. an output terminal for connection to said voltage controlled oscillator; d. a common terminal for said input and output terminals; e. filter means having inputs connected to said first and second input terminals and said common terminal, and having an output; f. a first resistor connected between said filter output and said output terminal; g. a second resistor and a first capacitor connected in series between said output terminal and said common terminal; h. a second capacitor connected in parallel with said second resistor; i. and first and second diodes each connected in parallel with said second resistor in reverse poled directions.
Claim 8
Dependent Claim
148 words
An improved circuit for connecting a phase detector and an acquisition circuit to a voltage controlled oscillator in a phase locked loop comprising: a. a first input terminal for connection to said phase detector; b. a second input terminal of connection to said acquisition circuit; c. an output terminal for connection to said voltage controlled oscillator; d. a common terminal for said input and output terminals; e. filter means having inputs connected to said first and second input terminals and said common terminal, and having an output; f. a first resistor connected between said filter output and said output terminal; g. a second resistor and a first capacitor connected in series between said output terminal and said common terminal; h. a second capacitor connected in parallel with said second resistor; i. and first and second diodes each connected in parallel with said second resistor in reverse poled directions.
Claim 9
Dependent Claim
16 words
The improved circuit of claim 6 wherein said filter means comprise first and second twin-T filters.
Claim 10
Dependent Claim
44 words
The improved circuit of claim 6 or claim 7 and further comprising third and fourth diodes connected between an intermediate terminal of said filter means and said output terminal, said third and fourth diodes being poled in reverse directions relative to said output terminal.
Claim 11
Dependent Claim
18 words
The improved circuit of claim 6 or claim 7 wherein said first and second diodes are Schottky type.
Claim 12
Dependent Claim
15 words
The improved circuit of claim 8 wherein said first and second diodes are Schottky type.
Claim 13
Dependent Claim
29 words
The improved circuit of claim 6 or claim 7 wherein said second resistor is connected to said output terminal and said first capacitor is connected to said common terminal.
Claim 14
Dependent Claim
26 words
The improved circuit of claim 8 wherein said second resistor is connected to said output terminal and said first capacitor is connected to said common terminal.
Claim 15
Dependent Claim
26 words
The improved circuit of claim 9 wherein said second resistor is connected to said output terminal and said first capacitor is connected to said common terminal.
Claim 16
Dependent Claim
26 words
The improved circuit of claim 10 wherein said second resistor is connected to said output terminal and said first capacitor is connected to said common terminal.
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) | 1985-12-06 | 1986-06-07 | 1986-12-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-12-06 | 1990-06-07 | 1990-12-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-12-06 | 1994-06-07 | 1994-12-07 | $7700.00 | Window Closed / Lapsed |