LTC6268 – 500MHz Ultra-Low Bias Current FET Input Op Amp


  • Gain Bandwidth Product: 500MHz
  • –3dB Bandwidth (A = 1): 350MHz
  • Low Input Bias Current:
    ±3fA Typ. Room Temperature
    4pA Max at 125°C
  • Current Noise (100kHz): 5.5fA/√Hz
  • Voltage Noise (1MHz): 4.3nV/√Hz
  • Extremely Low CIN 450fF
  • Rail-to-Rail Output
  • Slew Rate: 400V/μs
  • Supply Range: 3.1V to 5.25V
  • Quiescent Current: 16.5mA
  • Harmonic Distortion (2VP-P):
    –100dB at 1MHz
    –80dB at 10MHz
  • Operating Temp Range: –40°C to 125°C
  • Single in 8-Lead SO-8, 6-Lead TSOT-23 Packages
  • Dual in 8-Lead MS8, 3mm × 3mm 10-Lead DFN 10 Package

The LTC®6268/LTC6269 is a single/dual500MHzFET-input operational amplifier with extremely low input bias current and low input capacitance. It also features low input referred current noise and voltage noise making it an ideal choice for high speed trans impedance amplifiers, CCD output buffers, and high-impedance sensor amplifiers. Its low distortion makes the LTC6268/LTC6269 an ideal amplifier for driving SAR ADCs.
LTC6268 – 500MHz Ultra-Low Bias Current FET Input Op Amp

Product Lifecycle
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Demonstration Circuit 2414A has layouts for three channels of SOT-23 trans impedance amplifiers. Each of the three layouts applies different techniques achieving various parasitic feedback capacitances (CF). The upper channel, Ub3, assumes a low Trans impedance gain, has a parasitic CF of 0.1pF, and provides a footprint for an additional component CbF in an 0402 footprint (C29). The lower channel, U1, assumes high trans impedance gain and was laid out to minimize CF, achieving approximately 7fF, although the real situation is more complex. The middle channel, U2, assumes a middle case. The outputs of the circuit are laid out for SMA edge connectors. The inputs consist of six pads per channel along the edge where a through-hole photodiode can be mounted, with provision for any photodiode pin out.

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