Electrical Engineering Department Network Lab.

Transcription

1 Electrcal Engneerng Department Network Lab. Objecte: - Experment on -port Network: Negate Impedance Conerter To fnd the frequency response of a smple Negate Impedance Conerter Theory: Negate Impedance conerson s a functon yeldng (normally grounded) mpedance that s proportonal to the negate of gen mpedance (grounded or floatng). The fgure shows a Negate Impedance Conerter (NIC). z _ + z 0 I z Assumng deal opamps V 0 V + V V0 I V I If then For proper nerson there must be a bas path for each opamp nput and more negate than poste feedback whch requres / >, Where s the source mpedance S / S The crcut nerts mpedances only at frequences. Where the op amp open-loop gan can be consdered nfnte

2 Crcut Dagram I To CO round 0 K 3 + _ + V V nf 0 K Ch- of CO Procedure. Connect the crcut as shown on a bread-board. Apply Snusodal Voltage wth Frequency aryng from KHz on wards wth a peak-to-peak ampltude of V (adjust for undstorted output) 3. Measure the phase as well magntude of the nput and output 4. Plot nput on a Sem-Log graph paper 5. Take the tracng for 3 cases Dscusson Questons. Why the negate mpedance characterstcs are not possble n all frequency range?. Can you synthesze an nductor from a capactor usng ths crcut? Justfy your answer. 3. What could be the reasons for dstorton of n the output oltage?

3 Electrcal Engneerng Department Network Lab. Objecte: - Study of the yrator crcut and ts applcaton n syntheszng Inductors To fnd the frequency response of a yrator Crcut A yrator s an deal two-port element defned by the followng equatons.v.v Fg. the yrator epresentaton Propertes of the deal gyrator crcut: The deal gyrator s a non-energetc element,.e. at all tmes the power delered to the two-port dentcally zero: Another nterestng property s the mpedance gyraton gen by. V V L L Fg. A gyrator termnated at the output port wth a resstor Capactor-to-Inductor Mutaton property: An nterestng property s the followng: f the output port of an deal gyrator s termnated wth a capactor as shown n fg.3, the nput port behaes lke an nductor. Thus a gyrator s a useful element n the desgn of nductor less flters.

4 C L Fg.- Capactor to Inductor Mutaton Property d C d L ( (3) dt dt ) C yrtor : L C ( 4 ) C0nF, 00 nf, µf 0K LK Buld the crcut as shown n Fg.4 ( V DD V and V SS V ). Let C s 0nF, 0nF, or uf. (You need to measure only one case). Let l be K. Verfy that the crcut works as an nductor

5 (.e., whether the nput mpedance s nducte, n the sense that the current lags the oltage 0 by 90 ). Set the output of the functon generator to a V PP, KHz sne wae 0 DC offset. Usng the scope, dsplay and measure both the oltage and the current of the nductor. Check whether the current of the nductor lags ts oltage. You can use the X/Y mode of the scope as well. Set dfferent sne wae frequences (from 00Hz, to 0 khz), and repeat the preous measurement. Procedure. Connect the crcut as shown on a bread-board. Apply Snusodal Voltage wth Frequency aryng from khz on wards wth a peak-to-peak ampltude of V (adjust for to get undstorted output) 3. Measure the phase as well magntude of the nput and output 4. Plot nput on Sem-log graph paper Dscusson Questons Q. Why ths crcut s named as a yrator crcut? Q. Dere the expresson (4) pertanng to Fg.4 Q 3. What s the frequency when there s an exact 90 phase shft? Explan the reason of ths behaor. Q4. Name few commercally aalable yrator chps state the applcatons