Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsLinear ICsLinear IC - Amplifier - Video buffering 140 MHz SOIC 8

LT1227

APPLICATIO S

DESCRIPTIO

FEATURES

TYPICAL APPLICATIO

140MHz Video Current

Feedback Amplifier

■

140MHz Bandwidth: A

= 2, R

= 150Ω

■

1100V/µs Slew Rate

■

Low Cost

■

30mA Output Drive Current

■

0.01% Differential Gain

■

0.01° Differential Phase

■

High Input Impedance: 14MΩ, 3pF

■

Wide Supply Range: ±2V to ±15V

■

Shutdown Mode: I

< 250µA

■

Low Supply Current: I

= 10mA

■

Inputs Common Mode to Within 1.5V of Supplies

■

Outputs Swing Within 0.8V of Supplies

The LT

1227 is a current feedback amplifier with wide

bandwidth and excellent video characteristics. The low

differential gain and phase, wide bandwidth, and 30mA

output drive current make the LT1227 well suited to drive

cables in video systems.

A shutdown feature switches the device into a high imped-

ance, low current mode, allowing multiple devices to be

connected in parallel and selected. Input to output isola-

tion in shutdown is 70dB at 10MHz for input amplitudes up

to 10V

P-P

. The shutdown pin interfaces to open collector

or open drain logic and takes only 4µs to enable or disable.

The LT1227 comes in the industry standard pinout and

can upgrade the performance of many older products. For

a dual or quad version, see the LT1229/1230 data sheet.

The LT1227 is manufactured on Linear Technology’s

proprietary complementary bipolar process.

Video Cable Driver Differential Gain and Phase

vs Supply Voltage

–

75Ω

CABLE

OUT

75Ω

LT1227

75Ω

OUT

= 1

1227 TA01

■

Video Amplifiers

■

Cable Drivers

■

RGB Amplifiers

■

Test Equipment Amplifiers

■

50Ω Buffers for Driving Mixers

SUPPLY VOLTAGE (±V)

DIFFERENTIAL PHASE (DEG)

0.12

0.16

0.20

LT1227 • TA02

0.08

0.04

0.12

0.16

0.20

0.08

0.04

DIFFERENTIAL GAIN (%)

NTSC COMPOSITE

f = 3.58MHz

∆φ

∆G

, LTC and LT are registered trademarks of Linear Technology Corporation.

Summary of content (12 pages)

PAGE 1
LT1227 140MHz Video Current Feedback Amplifier U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO 140MHz Bandwidth: AV = 2, RL = 150Ω 1100V/µs Slew Rate Low Cost 30mA Output Drive Current 0.01% Differential Gain 0.01° Differential Phase High Input Impedance: 14MΩ, 3pF Wide Supply Range: ±2V to ±15V Shutdown Mode: IS < 250µA Low Supply Current: IS = 10mA Inputs Common Mode to Within 1.5V of Supplies Outputs Swing Within 0.
PAGE 2
LT1227 U U RATI GS W W W W AXI U U ABSOLUTE PACKAGE/ORDER I FOR ATIO (Note 1) Supply Voltage ..................................................... ±18V Input Current ...................................................... ±15mA Output Short Circuit Duration (Note 2) ........ Continuous Operating Temperature Range LT1227C .................................................. 0°C to 70°C LT1227M (OBSOLETE) .................... – 55°C to 125°C Storage Temperature Range .................
PAGE 3
LT1227 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCM = 0, ±5V ≤ VS ≤ ±15V, pulse tested, unless otherwise noted.
PAGE 4
LT1227 U W TYPICAL PERFOR A CE CHARACTERISTICS Voltage Gain and Phase vs Frequency, Gain = 6dB 135 225 4 3 VS = ±15V RL = 100Ω RF = 910Ω 1 0 0.1 RF = 750Ω 100 RF = 1k 80 60 40 RF = 2k 20 0 1 10 FREQUENCY (MHz) 0 100 2 4 6 8 10 12 14 SUPPLY VOLTAGE (±V) LT1227 • TPC01 135 20 180 GAIN 225 18 17 16 VS = ±15V RL = 100Ω RF = 825Ω 15 14 0.1 120 100 RF = 250Ω RF = 500Ω 80 RF = 750Ω 60 RF = 1k 40 RF = 2k 41 135 40 180 225 37 35 34 0.
PAGE 5
LT1227 U W TYPICAL PERFOR A CE CHARACTERISTICS Maximum Capacitive Load vs Feedback Resistor Total Harmonic Distortion vs Frequency 0.1 10000 VS = ±5V VS = ±15V 100 10 2 1 FEEDBACK RESISTOR (kΩ) VO = 7VRMS 3 1k 10k FREQUENCY (Hz) OUTPUT SATURATION VOLTAGE (V) –1.5 –2.0 2.0 1.5 V – = –2V TO –18V –0.5 70 RL = ∞ ±2V ≤ VS ≤ ±18V –1.0 1.0 0.
PAGE 6
LT1227 U W TYPICAL PERFOR A CE CHARACTERISTICS Settling Time to 1mV vs Output Step Settling Time to 10mV vs Output Step 10 VS = ±15V RF = RG = 1k 8 13 12 4 NONINVERTING 2 INVERTING 0 –2 –4 4 2 NONINVERTING 0 INVERTING –2 –4 8 –8 5 60 40 SETTLING TIME (ns) 80 –10 100 4 4 0 12 16 8 SETTLING TIME (µs) 1M 10M FREQUENCY (Hz) 0.10 0.20 VS = ±15V AV = 2 RL = 1k RF = 1k RG = 1k 1M 10M 2ND 3RD –50 VS = ±15V AV = 2 RL = 1k RF = 1k RG = 1k 0.
PAGE 7
LT1227 W W SI PLIFIED SCHE ATIC 7 14k NULL 1 V+ NULL 5 CURRENT SOURCE BIAS 8 S/D +IN 3 2 –IN 6 VOUT 4 V– 1227 SS U W U UO APPLICATI S I FOR ATIO The LT1227 is a very fast current feedback amplifier. Because it is a current feedback amplifier, the bandwidth is maintained over a wide range of voltage gains. The amplifier is designed to drive low impedance loads such as cables with excellent linearity at high frequencies.
PAGE 8
LT1227 U W U UO APPLICATI S I FOR ATIO and inverting input bias current will change. The offset voltage changes about 500µV per volt of supply mismatch. The inverting bias current can change as much as 5.0µA per volt of supply mismatch, though typically the change is less than 0.5µA per volt.
PAGE 9
LT1227 U W U UO APPLICATI S I FOR ATIO Shutdown Large-Signal Transient Response, AV = +2 VOUT RF = 1k, RG= 1k, RL = 400Ω AI03 Large-Signal Transient Response, AV = –2 The LT1227 has a high impedance, low supply current mode which is controlled by Pin 8. In the shutdown mode, the output looks like a 12pF capacitor and the supply current drops to approximately the Pin 8 current. The shutdown pin is referenced to the positive supply through an internal pullup circuit (see the simplified schematic).
PAGE 10
LT1227 UO TYPICAL APPLICATI S MUX Amplifier MUX Amplifier The shutdown function can be effectively used to construct a MUX amplifier. A two-channel version is shown, but more inputs could be added with suitable logic. By configuring each amplifier as a unity-gain follower, there is no loading by the feedback network when the amplifier is off. The open drains of the 74C906 buffers are used to interface the 5V logic to the shutdown pin.
PAGE 11
LT1227 U PACKAGE DESCRIPTIO J8 Package 8-Lead CERDIP (Narrow .300 Inch, Hermetic) (Reference LTC DWG # 05-08-1110) 0.300 BSC (0.762 BSC) 0.008 – 0.018 (0.203 – 0.457) CORNER LEADS OPTION (4 PLCS) 0° – 15° 0.023 – 0.045 (0.584 – 1.143) HALF LEAD OPTION 0.045 – 0.068 (1.143 – 1.727) FULL LEAD OPTION NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS 0.405 (10.287) MAX 0.005 (0.127) MIN 0.015 – 0.060 (0.381 – 1.524) 8 0.014 – 0.026 (0.360 – 0.660) 0.100 (2.54) BSC 5 0.025 (0.
PAGE 12
LT1227 UO TYPICAL APPLICATI S Single Supply AC-Coupled Amplifier Noninverting Single Supply AC-Coupled Amplifier Inverting 3.58MHz Oscillator 15V 5V 5V 4.7µF + + AV = 10k 22µF 100pF 10k 2.2µF – 3.579545MHz + + VOUT 75pF 10k + LT1227 2N3904 510Ω ≈ 10 RS + 51Ω BW = 14Hz to 60MHz + VIN 1N4148 100k 4.