tailieunhanh - FET Circuit Applications

The 2N4393 is operated as a Miller integrator. The high Yfs of the 2N4393 (over 12,000 mmhos @ 5 mA) yields a stage gain of about 60. Since the equivalent capacitance looking into the gate is C times gain and the gate source resistance can be as high as 10 MX, time constants as long as a minute can be achieved. | FET Circuit Applications The 2N4339 JFET was selected because of its low Igss 100 pA very-low Id OFF 50 pA and low pinchoff volt- TL H 6791 -2 Long Time Comparator The 2N4393 is operated as a Miller integrator. The high Yfs of the 2N4393 over 12 000 mmhos @ 5 mA yields a stage gain of about 60. Since the equivalent capacitance looking into the gate is C times gain and the gate source resistance can be as high as 10 MX time constants as long as a minute can be achieved. National Semiconductor Application Note 32 February 1970 age. Leakages of this level put the burden of circuit performance on clean solder-resin free low leakage circuit layout. TL H 6791 -3 JFET AC Coupled Integrator This circuit utilizes the m-amp technique to achieve very high voltage gain. Using Ci in the circuit as a Miller integrator or capacitance multiplier allows this simple circuit to handle very long time constants. FET Circuit Applications AN-32 1995 National Semiconductor corporation TL H 6791 RRD-B30M115 Printed in U. S. A. TL H 6791-4 Ultra-High Zin AC Unity Gain Amplifier Nothing is left to chance in reducing input capacitance. The 2N4416 which has low capacitance in the first place is operated as a source follower with bootstrapped gate bias resistor and drain. Any input capacitance you get with this circuit is due to poor layout techniques. SHUNT PEAKING COIL TL H 6791-6 TL H 6791-5 FET Cascode Video Amplifier The FET cascode video amplifier features very low input loading and reduction of feedback to almost zero. The 2N3823 is used because of its low capacitance and high Yfs. Bandwidth of this amplifier is limited by Rl and load capacitance. JFET Pierce Crystal Oscillator The JFET Pierce crystal oscillator allows a wide frequency range of crystals to be used without circuit modification. Since the JFET gate does not load the crystal good Q is maintained thus insuring good frequency stability. 2 TL H 6791-7 FETVM-FET Voltmeter This FETVM replaces the function ot the VTVM while at .