US4684832A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Analog circuit improvement in a digital integrated circuit technology
Assignee: Nortel Networks Ltd
•
Filing: 1986-04-29
•
Granted: 1987-08-04
•
Expires: 2006-04-29
Abstract
Abstract A CMOS integrated filter includes a passive network of resistive and capacitive paired elements and a first differential amplifier, for implementing a second order low pass filter function. A second amplifier is connected in voltage following configuration at an input of the first amplifier. A filter output is provided by an output of the second amplifier.
Inventors
- 👤 Thomas N. Little
- 👤 Lorenzo L. Longo
- 👤 Sun-Shiu D. Chan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:12
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/1204; H03H11/1217
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
137 words
A filter, for analog signals, comprising: a filter input electrode, for receiving an analog signal; a filter output electrode, for providing a filtered analog signal; a first amplifier being a differential amplifier and having an output and inverting and non-inverting inputs; a first resistive capacitive element and a second resistive capacitive element being connected in series between the filter input electrode and the non-inverting input to provide a resistive path therebetween, a capacitance electrode of the first resistive capacitive element being connected to the output and the inverting input, and a capacitance electrode of the second resistive capacitive element being connected to ground; and a second amplifier being connected in voltage follower configuration between the non-inverting input of the first amplifier and the filter output electrode, for providing the filterd analog signal at the filter output electrode.
Claim 2
Dependent Claim
137 words
A filter, for analog signals, comprising: a filter input electrode, for receiving an analog signal; a filter output electrode, for providing a filtered analog signal; a first amplifier being a differential amplifier and having an output and inverting and non-inverting inputs; a first resistive capacitive element and a second resistive capacitive element being connected in series between the filter input electrode and the non-inverting input to provide a resistive path therebetween, a capacitance electrode of the first resistive capacitive element being connected to the output and the inverting input, and a capacitance electrode of the second resistive capacitive element being connected to ground; and a second amplifier being connected in voltage follower configuration between the non-inverting input of the first amplifier and the filter output electrode, for providing the filterd analog signal at the filter output electrode.
Claim 3
Dependent Claim
163 words
In a CMOS integrated circuit, power and ground electrodes for connection across a source of power, an active filter circuit and a digital circuit means, the active filter circuit comprising: input and output electrodes, the output electrode being connected to the digital circuit means; a first differential amplifier having an output and inverting and non-inverting inputs; a first resistive capacitive element and a second resistive capacitive element being connected in series between the input electrode and the non-inverting input, to provide a resistive path therebetween, a capacitance electrode of the first resistive capacitive element being connected to the output and to the inverting input, and a capacitance electrode of the second resistive capacitive element being connected to the ground electrode; and a second differential amplifier including an output and an inverting input being connected together to said output electrode, and a non-inverting input being connected to a junction of the second resistive capacitive element and the non-inverting input of the first differential amplifier.
Claim 4
Dependent Claim
163 words
In a CMOS integrated circuit, power and ground electrodes for connection across a source of power, an active filter circuit and a digital circuit means, the active filter circuit comprising: input and output electrodes, the output electrode being connected to the digital circuit means; a first differential amplifier having an output and inverting and non-inverting inputs; a first resistive capacitive element and a second resistive capacitive element being connected in series between the input electrode and the non-inverting input, to provide a resistive path therebetween, a capacitance electrode of the first resistive capacitive element being connected to the output and to the inverting input, and a capacitance electrode of the second resistive capacitive element being connected to the ground electrode; and a second differential amplifier including an output and an inverting input being connected together to said output electrode, and a non-inverting input being connected to a junction of the second resistive capacitive element and the non-inverting input of the first differential amplifier.
References Cited (Backward Citations)
US3204192A
Cited
US3621407A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-08-03 | 1991-02-02 | 1991-08-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-08-03 | 1995-02-02 | 1995-08-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-08-03 | 1999-02-02 | 1999-08-04 | $7700.00 | Window Closed / Lapsed |