LT1191 OUUWUAPPLICATIS I FOR ATIO The ability to maintain shutoff is shown on the curve Other precautions include: Shutdown Supply Current vs Temperature in the Typical 1. Use a ground plane (see Design Note 50, High Fre- Performance Characteristics section. At very high quency Amplifier Evaluation Board). elevated temperatures it is important to hold the SHDN pin close to the negative supply to keep the supply current 2. Do not use high source impedances. The input from increasing. capacitance of 2pF and RS = 10k, for instance, will give an 8MHz – 3dB bandwidth. Murphy Circuits 3. PC board socket may reduce stability. There are several precautions the user should take when 4. A feedback resistor of 1k or lower reduces the effects using the LT1191 in order to realize its full capability. of stray capacitance at the inverting input. (For in- Although the LT1191 can drive a 30pF load, isolating the stance, closed-loop gain of 2 can use R capacitance with 10Ω can be helpful. Precautions prima- FB = 300Ω and R rily have to do with driving large capacitive loads. G = 300Ω.) Driving Capacitive LoadDriving Capacitive Load LT1191 • TA11 LT1191 • TA12 AV = –1, IN DEMO BOARD, CL = 30pF AV = –1, IN DEMO BOARD, CL = 30pF WITH 10Ω ISOLATING RESISTOR Murphy Circuits 5V 5V 5V 3 7 3 3 7 7 + + + COAX 6 6 6 LT1191 LT1191 LT1191 2 2 2 – 4 – 4 – 4 1X SCOPE –5V –5V –5V PROBE SCOPE PROBE LT1191 • TA13 An Unterminated Cable IsA 1X Scope Probe Is aA Scope Probe on the Invertinga Large Capacitive LoadLarge Capacitive LoadInput Reduces Phase Margin 10