Interface - Filters

Interface - Filters - Active

Part Number	Description / PDF	Quantity
LTC1063CN8#PBF Analog Devices, Inc.	IC FILTER 50KHZ LOWPASS 8DIP	302
LTC1563-3CGN#PBF Analog Devices, Inc.	IC FILTER 256KHZ LOWPASS 16SSOP	436
LTC1062CSW#TRPBF Analog Devices, Inc.	IC FILTER 20KHZ LOWPASS 16SOIC	0
MAX7444ETA Analog Devices, Inc.	3-CH VIDEO RECONSTRUCTION FILTER	1946
LTC1068-200IG#PBF Analog Devices, Inc.	IC FILTER 25KHZ SWITCHED 28SSOP	362
MAX275ACPP Analog Devices, Inc.	CONTINUOUS-TIME ACTIVE FILTER	27
LTC1264-7CSW#TRPBF Analog Devices, Inc.	IC FILTER 200KHZ LINEAR 16SOIC	0
LTC1569CS8-6#TRPBF Analog Devices, Inc.	IC FILTER 64KHZ LINEAR PHS 8SOIC	0
HMC891ALP5E Analog Devices, Inc.	IC FILTER BAND PASS 32LFCSP	255
MAX292EPA-G095 Analog Devices, Inc.	LOWPASS SWTCHED-CAPACITOR FILTER	344
MAX280CWE Analog Devices, Inc.	ZERO DC ERROR, LOWPASS FILTER	351
LTC1065IN8#PBF Analog Devices, Inc.	IC FILTER 50KHZ LOWPASS 8DIP	0
HMC882ALP5E Analog Devices, Inc.	IC FILTER LOW PASS 32LFCSP	11
LTC1067CGN#TRPBF Analog Devices, Inc.	IC FILTER 20KHZ SWITCHED 16SSOP	0
LTC1564CG#PBF Analog Devices, Inc.	IC FILTR 150KHZ ANTIALIAS 16SSOP	0
MAX7427CPA+ Analog Devices, Inc.	MAX7427 5TH-ORDER, LOWPASS, ELLI	7809
LTC1066-1CSW#TRPBF Analog Devices, Inc.	IC FILTER 50KHZ LOWPASS 18SOIC	0
MAX268ACWG Analog Devices, Inc.	UNIVERSAL BANDPASS FILTER	0
LTC1068IG#TRPBF Analog Devices, Inc.	IC FILTER 50KHZ SWITCHED 28SSOP	0
LTC1060ACN#PBF Analog Devices, Inc.	IC FILTER 30KHZ UNIV SWTCH 20DIP	229

Interface - Filters - Active

1. Overview

Active filters are electronic integrated circuits (ICs) that use active components (e.g., operational amplifiers) combined with passive elements (resistors, capacitors) to selectively attenuate or amplify specific frequency ranges. Unlike passive filters, active filters can provide gain, high input impedance, and low output impedance. They are critical in modern electronics for signal conditioning, noise suppression, and frequency domain processing in communication systems, audio equipment, and industrial control systems.

2. Main Types and Functional Classification

Type	Functional Characteristics	Application Examples
Low-Pass Filter (LPF)	Attenuates frequencies above cutoff; smooths signals	Audio DAC output filtering, ECG signal processing
High-Pass Filter (HPF)	Blocks DC components and low-frequency noise	Speaker crossover networks, AC coupling circuits
Band-Pass Filter (BPF)	Allows frequencies within a specific range	Wireless receiver front-ends, spectral analysis
Band-Reject Filter (BRF)	Attenuates a specific frequency band	Power line noise cancellation (50/60Hz), RFID systems
All-Pass Filter	Phase shifting without amplitude modification	Phase equalization in data transmission, delay equalizers

3. Structure and Components

Active filters typically consist of:
- Operational Amplifiers (Op-Amps): Provide gain and buffering.
- RC Networks: Define frequency response through resistor-capacitor combinations.
- Feedback Circuits: Stabilize performance and control Q-factor.
- Power Supply Pins: For biasing active components.
Modern IC implementations integrate these elements in monolithic packages, such as 8-pin SOIC or TSSOP, with laser-trimmed precision components.

4. Key Technical Specifications

Parameter	Description	Importance
Cutoff Frequency (f_c)	Frequency at -3dB point	Determines passband boundary
Voltage Gain (A_v)	Amplification factor	Signal strength adjustment
Quality Factor (Q)	Selectivity of frequency response	Controls transition band steepness
Input/Output Impedance	Matching with external circuits	Minimizes signal reflection
Power Supply Rejection Ratio (PSRR)	Noise immunity from power rails	Improves signal integrity

5. Application Areas

Telecommunications: DSL line drivers, 5G transceivers
Consumer Electronics: Equalizers in smartphones, noise-canceling headphones
Industrial: Sensor signal conditioning in PLCs
Medical Devices: Biopotential amplifiers for EMG/EKG
Automotive: Radar signal processing in ADAS

6. Leading Manufacturers and Products

Manufacturer	Representative Products	Key Features
Texas Instruments	LMV721, PGA2500	Rail-to-rail output, programmable gain
Analog Devices	LTC1564, MAX275	Low-power operation, tunable cutoff
STMicroelectronics	TS272, LMC662	CMOS technology, high precision
NXP Semiconductors	SAF7741, TDA7409	Audio-specific filtering with DSP integration

7. Selection Guidelines

Key considerations include:
- Required frequency range and stability over temperature
- Power consumption constraints (e.g., portable devices)
- Package size for space-constrained applications
- Component tolerance and aging effects
- Cost vs. performance trade-offs (e.g., using switched-capacitor filters for adjustable cutoff)

8. Industry Trends

Future developments focus on:
- Higher integration with ADC/DACs and DSP cores
- Miniaturization via 3D packaging and MEMS technology
- Adaptive filters using AI-driven parameter optimization
- Enhanced radiation hardness for automotive/aerospace applications
- Energy-efficient designs for IoT edge devices