Active Filters - Low Pass Filters Schematics

1MV Offset Clock-Tunable Monolithic 5-Pole Lowpass Filter - DN67  Design Notes (Linear Technology)

20 kHz MPX Low Pass Filter - This map, armored also enables automatic MONO / MPX through a low-pass filter, even with a multiplex on its entry by using an ON / ON, panning, the whole spectrum MPX more RDS is sent to the synthesizer, on the other hand when it is in a position MONO, the low-pass filter is activated and share its cutoff frequency at 15 KHz, only modulation G + D is sent to the synthesizer, as 19 KHz. 19 KHz carrier, the signal multiplex and subcarrier 57 KHz is thereby eliminated, which provides ease of use for example in a string of issue relay tuner, if the link between the issuer Departure and receiver re-issue was not of good quality stereo, you sufficient to switch to mono to improve sound quality, you can then connect the RDS encoder at the re-issuer.

3kHz Low Pass Filter Plus Audio AMP - This circuit uses a switched capacitor filter IC from National Semiconductor to filter signals with frequencies higher than the 3KHz needed for voice audio. The schematic includes an audio amplifier that is designed to drive a standard audio head phone. The circuit is described in more detail in the receiver section of Dave Johnson's Handbook of Optical Through the Air Communications. (this link is off-site)

8 bit microController implements Digital lowpass filter - 01/24/08 EDN-Design Ideas: A simple assembler routine fits a digital lowpass filter into a microcontroller..

Active 2nd Order Filters - The figures below illustrate using opamps as active 2nd order filters. Three 2nd order filters are shown, low pass, high pass, and bandpass. Each of these filters will attenuate frequencies outside their passband at a rate of 12dB per octave or 1/4 the voltage amplitude for each octave of frequency increase or decrease outside the passband.

Active Filter has Wideband Tuning Range - EDN-Design Ideas

Adjustable Filter Provides Lowpass Response - 03/01/01 EDN-Design Ideas: You can configure simple lowpass filters as pi sections with nominal three-pole, 0.1-dB Chebyshev response to provide a moderate amount of stopband selectivity. You can put four of these filters into one enclosure and then select discrete-filtering steps by using toggle switches. Manufacturers of commercially available stepped attenuators and adjustable baseband..

Akerberg-Mossberg AM Second Order Lowpass inverting

Applications for a DC Accurate Lowpass Switched-Capacitor Filter - AN20 Linear Technology Discusses  principles of operation of  LTC1062 and helpful hints for its application. Various application circuits are explained in detail with focus on how to cascade two LTC1062s and how to obtain notches. Noise and distortion performance are fully illustrated.

Audio AMP + 3kHz Filter - This circuit is the audio amp section for a complete optical transmitter. The circuit amplifies and filters the voice audio signals from an electret microphone. The circuit is described in more detail in the transmitter circuit section of Dave Johnson's Handbook of Optical Through the Air Communications. (this link is off-site)

Bach Second Order Lowpass non-inverting

Basic Introduction to Filters: Active, Passive & Switched-Capacitor - National Semiconductor Application Note

Berka-Herpy BH Second Order Lowpass non-inverting

Brick wall lowpass audio filter needs no tuning - EDN-Design Ideas Gyrator super capacitors eliminate the need for inductors in this 15-kHz filter.

Butterworth Filters

Centronics Port D/A converters & low-pass filter

Chebyshe Volt Bandpass Filter

Chebyshe Volt/Butterworth Filters

Chopper Amplifiers Complement a DC Accurate Low-Pass Filter - DN9  Design Notes (Linear Technology)

DC Accurate, Active RC Lowpass Filter - Extremely Easy to Use—A Single Resistor Value Sets the Cutoff Frequency (256Hz < fC < 256kHz)

Electric Field Disturbance Monitor-1 - This schematic is the power supply and front-end sections of the field monitor that is discussed in more detail at Electric Field Disturbance Monitor.  The system can detect human and animal motion by the electric fields they disturb.

Filter Akerberg-Mossberg (AM) Second Order Lowpass inverting

Filter Bach Second Order Lowpass non-inverting

Filter Berka-Herpy (BH) Second Order Lowpass non-inverting

Filter First Order Highpass III inverting

Filter First Order Highpass IV inverting

Filter First Order Lowpass I non-inverting

Filter First Order Lowpass II non-inverting

Filter First Order Lowpass III inverting

Filter Fliege Second Order Lowpass non-inverting

Filter KHN (Inverting Input) Second Order Lowpass inverting

Filter KHN (Non-Inverting Input) Second Order Lowpass non-inverting

Filter Mikhael-Bhattacharyya (MB) Second Order Lowpass non-inverting

Filter Multiple Feedback (MFB) Second Order Lowpass I inverting

Filter Multiple Feedback (MFB) Second Order Lowpass II inverting

Filter Sallen-Key (SK) Second Order Lowpass I non-inverting

Filter Sallen-Key (SK) Second Order Lowpass II non-inverting

Filter Tow-Thomas (TT) Second Order Lowpass non-inverting

Filter Twin-T Second Order Lowpass non-inverting

First Order Lowpass I non-inverting

First Order Lowpass II non-inverting

First Order Lowpass III inverting

Fliege Second Order Lowpass non-inverting

Generate CID/CIDCW Analog Signals - 12/07/00 EDN-Design Ideas: PDF contains multiple circuits, scroll to find this circuit….high-speed mP and active lowpass filters can generate CID (caller-ID)and CIDCW (caller-ID-on-callwaiting) analog signals (Figure 1). CID data transmits at 1200 baud FSK between the first and second 20-Hz ring of an incoming call. CIDCW uses a CAS (CPE Alert Signal) dual tone

KHN Inverting Input Second Order Lowpass inverting

KHN Non-Inverting Input Second Order Lowpass non-inverting

Low Pass Active Filter

Low Pass Active Filter Design Collection - This is a collection of inverting and non-inverting active low pass filter circuits.  I included one, two, three, four and six pole filter circuits.  You can change the component value ratios shown, to achieve any frequency cut-off you may need.  The circuit does not specify an operational amplifier.  The circuits should be used to select the needed resistor and capacitor components for a particular frequency knee and roll-off slope.

Low Pass Filter For FM 88-108 MHz - Filter used for eliminate unwanted harmonic frequency at second and third. Notch filter, Band Pass Filter (BPF), and High Pass Filter (HPF) sometime combined in constructing LPF design. Schematic below for FM Broadcast Lowpass Filter 88-108 MHz…

Low Pass Filter Subwoofer Circuit

Low pass filter-subwoofer filter

Low-Pass Filter RFI Filter - Circuit Ideas for Designers Application Notes Advanced Linear Devices, Inc.

Low-Sensitivity, Lowpass Filter Design - National Semiconductor Application Note

Lowpass 30 kHz Bessel filter offers high performance for audio applications - EDN-Design Ideas: Careful selection of amplifiers and components helps achieve the lowest levels of noise and distortion for higher-order filter.

Lowpass Filter Discriminates Step Input from Noise - EDN-Design Ideas

Lowpass Filter has Improved Step Response - EDN-Design Ideas

Lowpass Filter uses Only Two Values - 07/05/01 EDN-Design Ideas:. The composite lowpass filter uses interior constant-k full sections terminated by m-derived half-sections. For best passband response

LTC1560-1: Tiny 1MHz Lowpass Filter uses No Inductors - DN169  Design Notes (Linear Technology)

Mikhael-Bhattacharyya MB Second Order Lowpass non-inverting

OA-27: OA-27 Low-Sensitivity, Lowpass Filter Design - National Semiconductor Application Note

Precision Level Shifter has Excellent CMRR - 04/15/04 EDN-Design Ideas: Most designers make level shifters with op amps and 1%-tolerance discrete resistors. Discrete-resistor mismatching limits the op amp's CMMR (common-mode rejection ratio)to 40 dB, so you cannot use op amps in circuits that require high CMRR. Differential amplifiers.

RC Low-Pass Filter

RC lowpass filter expands microcomputer’s output Port - 06/21/07 EDN-Design Ideas: A simple lowpass RC filter allows a single output pin of a microcontroller to expand the number of output bits.

Replace Discrete Lowpass Filters with the LTC1563 Zero Design Effort Two Item Bom & No Surprises - DN251  Design Notes (Linear Technology)

Sallen-Key Low-Pass Filter

Sallen-Key SK Second order Lowpass I non-inverting

Sallen-Key SK Second order Lowpass II non-inverting

Single Resistor Tunes Lowpass Filter - 08/21/03 EDN-Design Ideas: Any tunable, second-order, active RC-filter section requires at least two thoroughly matched variable resistors. But the lowpass implementation in Figure 1 provides for wide-range cutoff-frequency control using only a single variable resistor, R. In addition to the resistor

SSB AF Filter - This is a simple filter that restricts the LF response a little as well providing quite a heavy HF roll-off. The prototype has enhanced a Yaesu FT101B that was only fitted with an AM IF filter. The IC is an LM358.

Tow-Thomas TT Second Order Lowpass non-inverting

Twin-T Second Order Lowpass non-inverting

Unique Applications for the LTC1062 Lowpass Filter - AN24 Linear Technology Highlights the LTC1062 as a lowpass filter in a phase lock loop. Describes how the loop's bandwidth can be increased and the VCO output jitter reduced when the LTC1062 is the loop filter. Compares it with a passive RC loop filter. Also discussed is the use of LTC1062 as simple bandpass and band stop filter.

Wideband filter uses image parameters - EDN-Design Ideas: You can design various lowpass and highpass filters using image parameters ( Reference 1 and Reference 2 ). By cascading a highpass and a lowpass filter.