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Dear Team,
Please kindly help about the specific bandwidth value of log114.Can it be used for amplify the 1Mhz small current signal effectively?Tks!
Hello Honle,
The LOG114 is usable for a 1 MHz input current providing the current resides within the ranges specified in the Electrical Characteristics tables. The information is shown below for +/-5 V operation, and an IREF of 1 uA. The bottom four lines indicate that the -3 dB bandwidth is greater than 1 MHz for the listed current levels. If the input current falls somewhere below 1 uA, then the bandwidth of the LOG114 will be less than 1 MHz. Therefore, it 1 uA would be a safe minimum input current level to assure 1 MHz operation.
Note that the configurable op amps A4 and A5 have a typical unity gain bandwidth of 15 MHz, and won't have much remaining open-loop gain (Aol) at 1 MHz. The upper left-hand graph on Pg. 10, A4 and A5 GAIN AND PHASE vs FREQUENCY, indicates only about 30 dB of Aol remaining at 1 MHz. Therefore, it is best to keep them in low closed-loop gain (Acl) configurations (a few volts per volt, as a maximum) to obtain reasonable performance from them.
Regards, Thomas
Precision Amplifiers Applications Engineering
