LT1228

PRODUCTION

100MHz Current Feedback Amplifier with DC Gain Control

Part Models: 6
1ku List Price: Starting From $5.02

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Overview

Very Fast Transconductance Amplifier
- Bandwidth: 75MHz
- Outputs Swing Within 0.8V of Supplies
- g_m = 10 × I_SET
- Low THD: 0.2% at 30mV_RMS Input
- Wide I_SET Range: 1µA to 1mA
Very Fast Current Feedback Amplifier
- Bandwidth: 100MHz
- Slew Rate: 1000V/µs
- Output Drive Current: 30mA
- Differential Gain: 0.04%
- Differential Phase: 0.1°
- High Input Impedance: 25MΩ, 6pF
Wide Supply Range: ±2V to ±15V
Inputs Common Mode to Within 1.5V of Supplies
Supply Current: 7mA
Available in 8-Lead PDIP and SOIC Packages

The LT1228 makes it easy to electronically control the gain of signals from DC to video frequencies. The LT1228 implements gain control with a transconductance amplifier (voltage to current) whose gain is proportional to an externally controlled current. A resistor is typically used to convert the output current to a voltage, which is then amplified with a current feedback amplifier. The LT1228 combines both amplifiers into an 8-pin package, and operates on any supply voltage from 4V (±2V) to 30V (±15V). A complete differential input, gain controlled amplifier can be implemented with the LT1228 and just a few resistors.

The LT1228 transconductance amplifier has a high impedance differential input and a current source output with wide output voltage compliance. The transconductance, g_m, is set by the current that flows into Pin5, I_SET. The small signal g_m is equal to ten times the value of I_SET and this relationship holds over several decades of set current. The voltage at Pin 5 is two diode drops above the negative supply, Pin 4.

The LT1228 current feedback amplifier has very high input impedance and therefore it is an excellent buffer for the output of the transconductance amplifier. The current feedback amplifier maintains its wide bandwidth over a wide range of voltage gains making it easy to interface the transconductance amplifier output to other circuitry. The current feedback amplifier is designed to drive low impedance loads, such as cables, with excellent linearity at high frequencies.

Applications

Video DC Restore (Clamp) Circuits
Video Differential Input Amplifiers
Video Keyer/Fader Amplifiers
AGC Amplifiers
Tunable Filters
Oscillators

Part Models: 6
1ku List Price: Starting From $5.02

Documentation

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal. View our quality and reliability program and certifications for more information.

Part Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LT1228CN8#PBF	8-Lead PDIP (Narrow 0.3 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1228CS8#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1228CS8#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1228IN8#PBF	8-Lead PDIP (Narrow 0.3 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1228IS8#PBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys
LT1228IS8#TRPBF	8-Lead SOIC (Narrow 0.15 Inch)	Material Declaration Reliablity Data Package Resources	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

Oct 8, 2024 - 24_0234 Migrating Bottom Trace Code Marking to Top Side Laser Marking for PDIP Package
		PCN24_0234_Form Material_Report Marking Comparison
LT1228CN8#PBF	PRODUCTION
LT1228IN8#PBF	PRODUCTION
Oct 11, 2022 - 22_0241 Epoxy Change from Henkel 8290 to 8290A for PDIP Package
		PCN22_0241_Form Material_Report Qualification Results Summary
LT1228CN8#PBF	PRODUCTION
LT1228IN8#PBF	PRODUCTION
Aug 6, 2022 - 22_0172 Laser Top Mark Conversion for PDIP Packages Assembled in ADPG [PNG]
		PCN22_0172_Form Material_Report Delta Qualification Matrix
LT1228CN8#PBF	PRODUCTION
LT1228IN8#PBF	PRODUCTION
Dec 14, 2023 - 22_0255 Epoxy Change from Henkel 8290 to 8290A for 8-Lead SOIC Package (PCN part 2 of 2)
		PCN22_0255_Form Material_Report Qualification Results Summary Delta Qualification Matrix
LT1228CS8#PBF	PRODUCTION
LT1228CS8#TRPBF	PRODUCTION
LT1228IS8#PBF	PRODUCTION
LT1228IS8#TRPBF	PRODUCTION
Jun 11, 2021 - 21_0060 Laser Top Mark for 8SOICN Assembled in ADPG, UTL and CRM
		PCN21_0060_Form Material_Report Delta Qualification Matrix
LT1228CS8#PBF	PRODUCTION
LT1228CS8#TRPBF	PRODUCTION
LT1228IS8#PBF	PRODUCTION
LT1228IS8#TRPBF	PRODUCTION

This is the most up-to-date revision of the Data Sheet.

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Tools & Simulations

LTspice

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LT1228

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