| Image | Part Number | Description / PDF | Quantity | Rfq |
|---|---|---|---|---|
 |
Broadcom |
IC FILTER DIGITAL 20QFN |
2898 |
|
|
Broadcom |
ACPL-0873T-500E: AUTO DIGITAL IC |
5932 |
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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.
| 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 |
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.
| Parameter | Description | Importance |
|---|---|---|
| Cutoff Frequency (fc) | Frequency at -3dB point | Determines passband boundary |
| Voltage Gain (Av) | 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 |
| 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 |
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)
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