MODUL PRAKTIKUM CURRENT FEEDBACK OPERATIONAL AMPLIFIER
Oleh: Reinhard NIM: 612009002
Skripsi Untuk melengkapi salah satu syarat memperoleh Gelar Sarjana Teknik Program Studi Teknik Elektronika Fakultas Teknik Elektronika dan Komputer Universitas Kristen Satya Wacana Salatiga
Januari 2015
INTISARI
Dalam kegiatan belajar mengajar di Fakultas Teknik Elektro dan Komputer Universitas Kristen Satya Wacana, penggunaan komponen operational amplifier (op-amp) sebagai komponen utama praktikum sangat sering dijumpai, namun jenis op-amp yang digunakan adalah voltage feedback amplifier. Padahal ada jenis op-amp lain yang belum pernah dibahas maupun dipraktikumkan yaitu current feedback operational amplifier. Prinsip kerja dari CFA (current feedback operational amplifier) jauh berbeda dari op-amp yang biasa digunakan, CFA memanfaatkan arus yang mengalir antara kedua inputan (inverting dan non inverting) dalam melakukan fungsi penguatan, sedangkan VFA (voltage feedback amplifier) memanfaatkan perbedaan nilai tegangan antara kedua inputan. Perbedaan cara kerja antara kedua penguat ini membuat CFA memiliki beberapa keunggulan dibanding dengan VFA diantaranya CFA dapat bekerja pada frekuensi masukan yang sangat tinggi. Persamaan- persamaan yang berlaku pada CFA juga berbeda dengan persamaan- persamaan pada VFA, dimana penggunaan resistor umpan balik negatif pada aplikasi- aplikasi untai yang menggunakan CFA sangat perlu diperhatikan karena adanya factor transimpedansi (Z). penggunaan nilai resistor umpan balik yang besar dapat mempengaruhi nilai penguatan yang dihasilkan oleh CFA, dimana nilai penguatan akan turun dari yang diharapkan, karena adanya pengaruh dari transimpedansi (Z) Modul praktikum yang dibuat pada tugas akir ini terdiri atas 8 topik praktikum yang sebagian besar berisi panduan bagi mahasiswa untuk mempelajari karakteristik dari CFA dan aplikasi – aplikasi CFA dalam beberapa jenis rangkaian penguat maupun tapis aktif yang sudah dikenal oleh mahasiswa, untuk nantinya dapat dibandingkan hasilnya dengan penggunaan VFA
ABSTRACT
In the teaching and learning activities of electrical and computer engineering faculty at Satya Wacana Christian University, the use of operational amplifier (op-amp) as the practical training main component are often to be seen, however the type of op-amp used in the practical training is voltage feedback operational amplifier. Besides the is another type of op-amp that never been discussed before by the lecturer, it is the current feedback operational amplifier The working principle of CFA (current feedback operational amplifier) is far different compare to the common op-amp, CFA utilize current which is flowing between both input of the CFA, meanwhile the VFA (Voltage feedback amplifier) utilize the voltage diference between both input of the VFA, because of this contrast the CFA has some advantage compare to the VFA which are that the CFA can work on high frequencies input. The equations work on CFA are also different copare to the VFA, where the usage of negative feedback resistor while designing an amplifeing circuit using CFA have to be necessary concerned because of the transimpedance (Z) factor. Using a high value of the negative feedback resistor will affect the gain value produced by the CFA, where the gain value will reduced from what is expected. The practice module made in this final project consist of 8 topics which mainly contain guidances for electrical engineering students to study about the CFA characteristic, kinds of CFA application as an amplifeing circuits and, some active filters that they have known, so they can compare the CFA practical training result with the use of VFA
KATA PENGANTAR
Puji Syukur ke hadirat Tuhan Yang Maha Esa, atas segala berkat dan karunia-Nya sehingga penulis dapat menyelesaikan studi dan skripsi di Fakultas Teknik Elektronika dan Komputer Universitas Kristen Satya Wacana. Penulis ingin mengucapkan terima kasih sebesar-besarnya kepada: 1. Haryono Trisnadi dan Sinawati Sadikun selaku Ayah dan Ibu, yang telah membesarkan dan membiayai kuliah penulis dengan penuh kasih sayang dan kesabaran 2. Bapak Ir. F. Dalu Setiaji, M.T selaku pembimbing 1 3. Bapak Deddy Susilo, M.Eng selaku pembimbing 2 4. Aletheia Anggelia Tonoro yang telah banyak memberi dukungan semangat selama menjalankan studi di FTEK UKSW
5. Teman- teman kos Kalipengging Amsal, Yonas, Yohanes Inka, Gde, Hendry, dan Veto, yang telah banyak membantu dalam perkuliahan di FTEK UKSW
6. Ivan Dwinanda dan Awang Astu yang banyak membantu selama hidup di kota Salatiga 7. Teman-teman 2009 8. Teman-Teman kafe Rindang . 9. Teman-teman lab skripsi 10. Semua keluarga besar FTEK UKSW mulai dari dosen sampai pegawai gedung C. Walaupun masih banyak kekurangan dalam pembuatan skripsi ini, penulis berharap skripsi ini dapat berguna dan dapat disempurnakan suatu hari kelak. Salatiga, 9 januari 2015 Penulis,
Reinhard
DAFTAR ISI INTISARI ........................................................................................................................................ i ABSTRACT .................................................................................................................................... ii KATA PENGANTAR ................................................................................................................... iii DAFTAR ISI.................................................................................................................................. iv DAFTAR GAMBAR .................................................................................................................... vii DAFTAR TABEL.......................................................................................................................... xi BAB I PENDAHULUAN ................................................................................................................1 1.1.
Tujuan ...............................................................................................................................1
1.2.
Latar Belakang ..................................................................................................................1
1.3.
Spesifikasi Sistem .............................................................................................................2
1.4.
Sistematika Penulisan .......................................................................................................3
BAB II DASAR TEORI ..................................................................................................................4 2.1.
Current Feedback Operational Amplifier.........................................................................4
2.2.
Karakterisitik Operational Amplifier ................................................................................5 2.2.1. Penguat tegangan open loop .................................................................................5 2.2.2. Hambatan masukan ...............................................................................................7 2.2.3. Bandwidth .............................................................................................................7 2.2.4. Slew rate................................................................................................................7 2.2.5. Transimpedansi (Z) ...............................................................................................8
2.3.
Current Feedback Op-amp sebagai penguat non-inverting ..............................................8
2.4.
Current Feedback Op-amp sebagai penguat inverting ....................................................10
BAB III PERANCANGAN ..........................................................................................................12 3.1.
Perancangan susunan pedoman praktikum .....................................................................12
3.2.
Perancangan Pedoman Praktikum...................................................................................13 3.2.1. Pengukuran Karakteristik Op-amp CFA (Lampiran A)......................................13 3.2.1.1. Pengukuran hambatan masukan kaki inverting dan non inverting opamp (Rin)................................................................................................................14 3.2.1.2. Pengukuran nilai transimpedansi ...................................................................15 3.2.1.3. Pengukuran tegangan keluaran maksimum ....................................................15
3.2.1.4. Pengukuran slew rate opamp current feedback ..............................................16 3.2.2. Karakteristik Rangkaian dasar Op-amp CFA(penguat membalik, penguat tak membalik, penguat penjumlah. Lampiran B) .....................................................16 3.2.2.1. Penguat tak membalik ....................................................................................17 3.2.2.2. Penguat membalik (Inverting) .......................................................................17 3.2.2.3. Penguat penjumlah (Summing Amplifier) .....................................................18 3.2.3. Pembatasan Lebar Pita Pada Penguat Berbasis CFA (Lampiran C) ...................19 3.2.4. Integrator Berbasis Op-amp CFA (Lampiran D) ................................................20 3.2.4.1. Integrator dengan CFA ...................................................................................20 3.2.4.2. Diferensiator dengan CFA .............................................................................21 3.2.5. Stabilitas dan Kompensasi Pada Op-amp CFA (Lampiran E) ............................22 3.2.6. Penguat selisih dan Penguat Instrumentasi berbasis Op-amp CFA (Lampiran F) ..............................................................................................24 3.2.6.1. Penguat selisih (Differential Amplifier) .........................................................25 3.2.6.2. Penguat Instrumentasi ....................................................................................26 3.2.7. Tapis-Tapis Aktif Berbasis Op-amp CFA (Lampiran G) ...................................27 3.2.8. Penguat Photocurrent Berbasis Op-amp CFA (Lampiran H) .............................33 BAB IV PENGUJIAN DAN ANALISIS ......................................................................................36 4.1.
Pengukuran Karakteristik Op-amp CFA .........................................................................36 4.1.1. Pengukuran hambatan masukan kaki inverting dan non inverting opamp (Rin) 36 4.1.2. Pengukuran nilai transimpedansi ........................................................................38 4.1.3. Pengukuran tegangan keluaran maksimum ........................................................42 4.1.4. Pengukuran slew rate ..........................................................................................44
4.2.
Karakteristik Rangkaian dasar Op-amp CFA(penguat membalik, penguat tak membalik, penguat penjumlah) .........................................................................................................45 4.2.1. Penguat tak membalik (non inverting amplifier) ................................................45 4.2.2. Penguat Inverting ................................................................................................52 4.2.3. Penguat penjumlah (summing amplifier)............................................................58
4.3.
Pembatasan Lebar Pita Pada Op-amp CFA ....................................................................62
4.4
Integrator Berbasis CFA .................................................................................................67 4.4.1. Integrator berbasis CFA ......................................................................................67
4.4.2. Diferensiator Berbasis CFA ................................................................................70 4.5.
Stabilitas dan Kompensasi Pada Op-amp CFA ..............................................................73
4.6.
Penguat selisih dan Penguat Instrumentasi berbasis Op-amp CFA ................................78 4.6.1. Penguat selisih (Differntial amplifier) ................................................................78 4.6.2. Penguat Instrumentasi Berbasis CFA .................................................................83
4.7.
Tapis-Tapis Aktif Berbasis Op-amp CFA ......................................................................86 4.7.1. Low pass filter orde 1 .........................................................................................86 4.7.2. High pass filter orde 1 .........................................................................................88 4.7.3. Low pass filter orde 2 .........................................................................................90 4.7.4. High pass filter orde 2 .........................................................................................93
4.8.
Penguat Photocurrent Berbasis Op-amp CFA ................................................................97
BAB V KESIMPULAN DAN SARAN ......................................................................................101 5.1.
Kesimpulan ...................................................................................................................101
5.2.
Saran Pengembangan ....................................................................................................102
DAFTAR PUSTAKA ..................................................................................................................103 LAMPIRAN A .............................................................................................................................104 LAMPIRAN B .............................................................................................................................108 LAMPIRAN C .............................................................................................................................114 LAMPIRAN D .............................................................................................................................115 LAMPIRAN E .............................................................................................................................118 LAMPIRAN F .............................................................................................................................122 LAMPIRAN G .............................................................................................................................125 LAMPIRAN H .............................................................................................................................133
DAFTAR GAMBAR Gambar 3.1. Konfigurasi pin LT-1227 ........................................................................13 Gambar 3.2.(a). Rangkaian Pengukur Hambatan masukan kaki non inverting ...........14 Gambar 3.2.(b). Rangkaian Pengukur Hambatan masukan kaki inverting..................14 Gambar 3.3. Internal CFA ...........................................................................................14 Gambar 3.4. Rangkaian Pengukur Transimpedansi .....................................................15 Gambar 3.5. Untai penguat Membalik untuk mencari Vomax ....................................15 Gambar 3.6. Untai penguat non inverting untuk mencari Vomax ...............................16 Gambar 3.7. Rangkaian pengukur slew rate ................................................................16 Gambar 3.8. Penguat tak membalik (non inverting) ....................................................17 Gambar 3.9. Rangkaian penguat inverting ..................................................................17 Gambar 3.10. Rangkaian penguat penjumlah ..............................................................18 Gambar 3.11. Grafik Bandwidth vs Tegangan supply LT-1227 .................................19 Gambar 3.12. Untai penguat tak membalik untuk mencari bandwidth .......................20 Gambar 3.13. Integrator dengan CFA..........................................................................20 Gambar 3.14. Diferensiator dengan CFA ....................................................................21 Gambar 3.15. Rangkaian penguat tak membalik untuk mencari stabilitas CFA .........22 Gambar 3.16. Sinyal keluaran RLC seri underdamped ...............................................23 Gambar 3.17. Rangkaian RLC seri ..............................................................................24 Gambar 3.18. Rangkaian Penguat selisih ....................................................................25 Gambar 3.19. Rangkaian Penguat Instrumentasi .........................................................26 Gambar 3.20. Rangkaian dan Low pass Filter orde 1 ..................................................27 Gambar 3.21. Rangkaian High pass Filter orde 1 ........................................................28 Gambar 3.22. Respon Frekuensi Butterworth Filter ....................................................30 Gambar 3.23. VCVS(Voltage controlled voltage source) ...........................................30 Gambar 3.24. Rangkaian low pass Filter orde 2 ..........................................................32 Gambar 3.25. Rangkaian High pass Filter orde 2 ........................................................32 Gambar 3.26. Symbol photodiode ...............................................................................33 Gambar 3.27. Rangkaian penguat photocurrent ..........................................................34 Gambar 4.1.(a). Untai untuk mencari Hambatan masukan pada kaki non inverting ...36
Gambar 4.1.(b). Untai untuk mencari Hambatan masukan pada kaki inverting..........36 Gambar 4.2. Untai Penguat tak membalik untuk mencari nilai transimpedansi ..........38 Gambar 4.3. Grafik frekuensi terhadap transimpedansi ..............................................41 Gambar 4.4. Untai penguat membalik untuk mencari Vomax ....................................42 Gambar 4.5. Sinyal Vomax pada penguat inverting(Volt/div=5volt) .........................42 Gambar 4.6. Untai penguat non inverting untuk mencari Vomax ...............................43 Gambar 4.7. Sinyal Vomax pada penguat non inverting(Volt/div=5volt) ..................43 Gambar 4.8. Untai untuk mencari nilai slewrate .........................................................44 Gambar 4.9. slew rate CFA..........................................................................................44 Gambar 4.10. Slew rate dalam 1 sumbu ......................................................................44 Gambar 4.11. Rangkaian penguat non-inverting .........................................................45 Gambar 4.12. Output non-inverting ketika R2=2kΩ, R1=1kΩ (volt/div=0,5volt) .....45 Gambar 4.13. Output non-inverting ketika R2=20kΩ, R1=10kΩ (volt/div=0,5volt) .46 Gambar 4.14. Output non-inverting ketika R2=200kΩ, R1=100kΩ (volt/div=0,5volt) .........................................................................................................46 Gambar 4.15. Output non-inverting ketika R2=1MΩ, R1=500kΩ (volt/div=0,5volt) .........................................................................................................47 Gambar 4.16. Tanggapan frekuensi penguat non-inverting berbasis CFA ..................51 Gambar 4.17. Rangkaian penguat membalik ...............................................................52 Gambar 4.18. Output inverting ketika R2=2kΩ, R1=1kΩ (volt/div=0,5volt) .............52 Gambar 4.19. Output inverting ketika R2=20kΩ, R1=10kΩ (volt/div=0,5volt) .........53 Gambar 4.20. Output inverting ketika R2=200kΩ, R1=100kΩ (volt/div=0,5volt) .....53 Gambar 4.21. Output inverting ketika R2=1MΩ, R1=500kΩ (volt/div=0,5volt) .......54 Gambar 4.22. Tanggapan frekuensi penguat inverting ................................................57 Gambar 4.23. Rangkaian penguat penjumlah ..............................................................58 Gambar 4.24. Output summing R1=1k, R2=1k, R3=1k (volt/div=1volt) ...................58 Gambar 4.25. Output summing R1=1k, R2=1k, R3=2k (volt/div=1volt) ...................59 Gambar 4.26. Output summing R1=100k, R2=100k, R3=100k (volt/div=1volt) .......59 Gambar 4.27. Output summing R1=100k, R2=100k, R3=200k (volt/div=1volt) .......60 Gambar 4.28. Penguat tak membalik untuk mencari bandwidth .................................62 Gambar 4.29. Bandwidth ketika Rf=1kΩ, Rg=100Ω,Vcc/Vee=+15/-15 ....................63
Gambar 4.30. Bandwidth ketika Rf=1kΩ, Rg=100Ω,Vcc/Vee=+7/-7 ........................64 Gambar 4.31. Bandwidth ketika Rf=2kΩ, Rg=200Ω,Vcc/Vee=+15/-15 ....................64 Gambar 4.32. Bandwidth ketika Rf=2kΩ, Rg=200Ω,Vcc/Vee=+7/-7 ........................65 Gambar 4.33. Bandwidth ketika Rf=10kΩ, Rg=1kΩ,Vcc/Vee=+15/-15 ....................66 Gambar 4.34. Rangkaian integrator berbasis CFA ......................................................67 Gambar 4.35. sinyal Vo dan Vi integrator dengan R1=10kΩ dan C1=10nF ..............67 Gambar 4.36. sinyal Vo dan Vi integrator dengan R1=1kΩ dan C1=100pF ..............68 Gambar 4.37. sinyal Vo dan Vi integrator dengan R1=100Ω dan C1=100pF ............69 Gambar 4.38. Rangkaian diferensiator berbasis CFA .................................................70 Gambar 4.39. sinyal Vo dan Vi diferensiator dengan R1=1kΩ dan C1=100nF ..........70 Gambar 4.40. sinyal Vo dan Vi diferensiator dengan R1=1kΩ dan C1=1nF ..............71 Gambar 4.41. sinyal Vo dan Vi diferensiator dengan R1=1kΩ dan C1=100pF ..........72 Gambar 4.42. Untai penguat tak membalik untuk mencari stabilitas CFA .................73 Gambar 4.43. Stabilitas saat R1 dan R2= 1kΩ ............................................................73 Gambar 4.44. Stabilitas saat R1 dan R2= 10kΩ ..........................................................73 Gambar 4.45. Stabilitas saat R1 dan R2= 5kΩ ............................................................74 Gambar 4.46. Stabilitas saat R1 dan R2= 500Ω ..........................................................74 Gambar 4.47. Rangkaian RLC seri pada Circuit maker ..............................................77 Gambar 4.48. Hasil Simulasi Rangkaian RLC pada Circuit maker .............................77 Gambar 4.49. Rangkaian penguat selisih (differential amp) .......................................78 Gambar 4.50. Vi1 dan Vo diff amp saat R1,R3=1kΩ dan R2,R4=1kΩ ......................79 Gambar 4.51. Vi2 dan Vo diff amp saat R1,R3=1kΩ dan R2,R4=1kΩ ......................80 Gambar 4.52. Vi1 dan Vo diff amp saat R1,R3=100Ω dan R2,R4=1kΩ ....................81 Gambar 4.53. Vi2 dan Vo diff amp saat R1,R3=100Ω dan R2,R4=1kΩ ....................81 Gambar 4.54. Vi1 dan Vo diff amp saat R1,R3=100Ω dan R2,R4=1kΩ ....................82 Gambar 4.55. Vi2 dan Vo diff amp saat R1,R3=100Ω dan R2,R4=1kΩ ....................82 Gambar 4.56. Rangkaian penguat instrumentasi .........................................................83 Gambar 4.57. Vo1 penguat instrumentasi (volt/div=0,5volt) ......................................85 Gambar 4.58. Vo2 penguat instrumentasi (volt/div=0,1volt) ......................................85 Gambar 4.59. Vo akir penguat instrumentasi (volt/div=0,5volt) .................................85 Gambar 4.60. rangkaian low pass filter orde 1 ............................................................86
Gambar 4.61. Tanggapan frekuensi LPF orde 1 berbasis CFA ...................................87 Gambar 4.62. rangkaian high pass filter orde 1 ...........................................................88 Gambar 4.63. Tanggapan frekuensi HPF orde 1 berbasis CFA ...................................89 Gambar 4.64. rangkaian lowpass filter orde 2 .............................................................90 Gambar 4.65. Tanggapan frekuensi LPF orde 2 berbasis CFA ...................................92 Gambar 4.66. faktor kualitas LPF orde 2 .....................................................................93 Gambar 4.67. rangkaian highpass filter orde 2 ............................................................93 Gambar 4.68. Respon frekuensi HPF orde 2 ...............................................................96 Gambar 4.69. rangkaian penguat photocurrent ............................................................97 Gambar 4.70. untai internal penguat photocurrent ......................................................98 Gambar 4.71. Rangkaian penyusun photodioda ........................................................100
DAFTAR TABEL Tabel 4.1. Respon frekuensi Rin pada kaki non-inverting.............................................................36 Tabel 4.2. Tegangan keluaran berdasarkan perubahan R1 dan r2 dalam mencari nilai Transimpedansi ......................................................................................................................38 Tabel 4.3. Transimpedansi saat R1 dan R2= 1kΩ .........................................................................39 Tabel 4.4. Transimpedansi saat R1 dan R2= 10kΩ .......................................................................40 Tabel 4.5. Transimpedansi saat R1 dan R2= 100kΩ .....................................................................40 Tabel 4.6. Transimpedansi saat R1 dan R2= 200kΩ .....................................................................40 Tabel 4.7. Respon Frekuensi penguat non inverting saat R2=2kΩ, R1=1kΩ ...............................45 Tabel 4.8. Respon Frekuensi penguat non inverting saat R2=20kΩ, R1=10kΩ ...........................46 Tabel 4.9. Respon Frekuensi penguat non inverting saat R2=200kΩ, R1=100kΩ .......................47 Tabel 4.10. Respon Frekuensi penguat non inverting saat R2=1MΩ, R1=500kΩ ........................47 Tabel 4.11. Respon Frekuensi penguat inverting saat R2=2kΩ, R1=1kΩ ....................................52 Tabel 4.12. Respon Frekuensi penguat inverting saat R2=20kΩ, R1=10kΩ ................................53 Tabel 4.13. Respon Frekuensi penguat inverting saat R2=200kΩ, R1=100kΩ ............................53 Tabel 4.14. Respon Frekuensi penguat inverting saat R2=1MΩ, R1=500kΩ ...............................54 Tabel 4.15. Respon Frekuensi penguat penjumlah R1=1k,R2=1k,R3=1k ....................................58 Tabel 4.16. Respon Frekuensi penguat penjumlah R1=1k,R2=1k,R3=2k ....................................59 Tabel 4.17. Respon Frekuensi penguat penjumlah R1=100k,R2=100k,R3=100k ........................59 Tabel 4.18. Respon Frekuensi penguat penjumlah R1=100k,R2=100k,R3=200k ........................60 Tabel 4.19. Respon frekuensi low pass filter orde 1 dengan Ra dan Rb =1kΩ, R1=1kΩ,C1=100pF ..........................................................................................86 Tabel 4.20. Respon frekuensi low pass filter orde 1 dengan Ra dan Rb =100kΩ, R1=1kΩ,C1=100pF ......................................................................................86 Tabel 4.21. Respon frekuensi high pass filter orde 1 dengan Ra dan Rb =1kΩ, R1=1kΩ,C1=10nF ............................................................................................88 Tabel 4.22. Respon frekuensi high pass filter orde 1 dengan Ra dan Rb =100kΩ, R1=1kΩ,C1=10nF ........................................................................................88 Tabel 4.23. Respon frekuensi low pass filter orde 2 dengan Ra, Rb =1kΩ, R1,R2=1kΩ,C1,C2=100pF.....................................................................................90
Tabel 4.24. Respon frekuensi low pass filter orde 2 dengan Ra, Rb =100kΩ, R1,R2=1kΩ,C1,C2=100pF.................................................................................90 Tabel 4.25. Respon frekuensi high pass filter orde 2 dengan Ra, Rb =1kΩ, R1,R2=1kΩ,C1,C2=100pF.....................................................................................94 Tabel 4.26. Respon frekuensi High pass filter orde 2 dengan Ra, Rb =100kΩ, R1,R2=1kΩ,C1,C2=100pF.................................................................................94 Tabel 4.27. Respon frekuensi penguat photocurrent dengan Cf=100pF .......................................97 Tabel 4.28. Respon frekuensi penguat photocurrent dengan Cf=50pF .........................................97
