DC-STABILIZED FAST AMPLIFIER

This amplifier functions over a wide range of gains, typically 1 - 10. It combines the LT1010 and a fast discrete stage with an LT1008 based dc stabilizing loop. Q1 and Q2 form a differential stage which single-ends into the LT1010. The circuit delivers 1 V pk-pk in to a typical 75-ohm video load. At A = 2, the gain is within 0.5 dB to 10 MHz with the -3-dB point occurring at 16 MHz. At A = 10, the gain is flat(plus or minus 0.5 dB to 4 MHz) with a -3- dB point at 8 MHz. The peaking adjustment should be optimized under loaded output conditions. This is a simple stage for fast applications where relatively low output swing is required. Its 1 V pk-pk output works nicely for video circuits. A possible problem is the relatively high bias current, typically 10 uA. Additional swing is possible, but more circuitry is needed. Circuit Diagram