Later, recovery nets (RV1+CV1 and RV2+ CV2) can be added in exactly the same manner as they were for the L-17C. They are now easier to design, as the cutoff voltage of A1 is now temperature independent.

Temperature compensation is discussed later.

Caution!  Do not apply input voltages exceeding +/- 2.2V to either input of A1 for extended periods.  Do not apply input pulses greater than +/-2.7 to either input.  Where there is a danger of this occurring, protection diodes should be used.  These conditions can cause reverse biasing of the input transistors that will degrade their performance. Similarly, the output of A1 is designed to drive positive pulses and has very little current available to drive negative output pulses.  (See section on bipolar operation on page 31 if it is necessary to use a bipolar output.)  To prevent reverse biasing the output transistors, if it is likely that negative outputs will occur that exceed the negative drive capability of A1, a protection diode should be placed from the output of A1, pin 6 or pin 34 to the compensation pin, pin 1.  The anode should be connected to the output and the cathode to the compensation pin.  Make sure to use a low capacitance diode or Schottky.

A2:    (Pins 29, 31, 32 33)

The DC comp pin (33) should not be used. Rather, use the same procedure as was described for A1, using the inverting input, pin 31. The PC17D-2 test board uses pin 31 because pin 32 is tied directly to a low output impedance source, the output of A1. If it is more convenient for your layout on your own board, pin 32 can be used, provided that you connect the output of A1 to the positive input of A2 through a 50, or 100Ω resistor. Use R10 VCC or R10 VEE.  There is a 200-ohm resistor from pin 31 to ground inside the IC, which should enable you to calculate the required resistor to the rails.

If A2 has an overshoot or undershoot, you can use a cap from pin 29 to 31 (C7 for overshoot removal and C9 to speed up), or a comp cap (C16) from pin 33 to ground to slow down. Cap sizes are in the 1 to 3 pf range. To run at 20 MHz, just increase the size of the comp cap to give the desired small signal rise time. In general, when one tries to slow an amp down using only a cap across the feedback, if you make this cap too large, you will see a notch, or a step in the front of the flat top of the pulse. Cut back a little on the feedback cap in this case, and increase the comp cap.

Connect pin 29 to pin 28 to couple A2 to A3. (They are already connected on the test board.) If you want to AC couple, connect through an appropriate size capacitor and connect a resistor to ground from pin 28 to provide base current for the positive input to A3.

The values used on our test board for high-speed operation were 2.2 pF (C7) across the feedback resistor and 0 pf for compensation.

A3:     (pins 24, 25, 26 and 28)

The DC trim pin (pin 25) functions exactly the same way as it did on the L-17C (R15) and associated pots.  The only other thing that needs adjustment on this amp is the speed.  To speed it up, we have found that it is most effective to use the RS3-CS3 combination connected to ground. You can also use C13 to speed up the rise time.