Datasheet LT1223 (Analog Devices) - 7

LT1223
W U TYPICAL PERFOR A CE CHARACTERISTICS Voltage Gain and Phase vs Total Harmonic Distortion vs 2nd and 3rd Harmonic Frequency Frequency Distortion vs Frequency
20 225 0.1 –20 V = 15V S ± V = 15V S ± V = 15V S ± 15 180 RF = RG = 1k V = 7V V = 2V O RMS O P-P 2ND R = 400Ω R = 100 10 135 PHASE SHIFT (DEGREES) L –30 L GAIN RF = RG =1k RF = 1k 3RD 5 90 A = 10dB V R = 100 R 1k L Ω L ≥ 0 45 –40 PHASE –5 0 0.01 R 1k L ≥ –10 –45 R = 100Ω –50 L VOLTAGE GAIN (dB) –15 –90 THD DISTORTION (dBc) –20 –135 –60 TOTAL HARMONIC DISTORTION (%) –25 –180 –30 –225 0.001 –70 1M 10M 100M 1G 10 100 1k 10k 100k 1 10 100 FREQUENCY (Hz) FREQUENCY (Hz) FREQUENCY (MHz) LT1223 • TPC20 LT1223 • TPC21 LT1223 • TPC22
Noninverting Amplifier Settling Noninverting Amplifier Settling Inverting Amplifier Settling Time to 10mV vs Output Step Time to 1mV vs Output Step Time vs Output Step
10 10 10 A = +1 A = –1 V A = +1 V V 8 R 8 R = 1k 8 R = 1k TO 10mV F = 1k F F ± V = 15V V = 15V S ± V = 15V S ± 6 S TO 10mV 6 6 R = 1k R = 1k TO 1mV R = 1k L L L 4 4 4 TO 1mV 2 2 2 0 0 0 –2 –2 –2 OUTPUT STEP (V) OUTPUT STEP (V) OUTPUT STEP (V) –4 –4 –4 TO 1mV TO 10mV –6 –6 TO 1mV –6 TO 10mV –8 –8 –8 –10 –10 –10 0 20 40 60 80 100 0 1 2 0 20 40 60 80 100 SETTLING TIME (ns) SETTLING TIME ( s) µ SETTLING TIME (ns) LT1223 • TPC23 LT1223 • TPC24 LT1223 • TPC25
U U W U APPLICATIO S I FOR ATIO Current Feedback Basics
The small-signal bandwidth of the LT1223, like all current does in a voltage feedback op amp, the closed-loop feedback amplifiers, isn’t a straight inverse function of the bandwidth does not change. This is because the equiva- closed-loop gain. This is because the feedback resistors lent gain bandwidth product of the current feedback am- determine the amount of current driving the amplifier’s plifier is set by the Thevenin equivalent resistance at the internal compensation capacitor. In fact, the amplifier’s inverting input and the internal compensation capacitor. feedback resistor (R By keeping R F) from output to inverting input F constant and changing the gain with RG, the works with internal junction capacitances of the LT1223 to Thevenin resistance changes by the same amount as the set the closed-loop bandwidth. change in gain. As a result, the net closed-loop bandwidth of the LT1223 remains the same for various closed-loop Even though the gain set resistor (RG) from inverting input gains. to ground works with RF to set the voltage gain just like it 1223fb 7