SISTEM ELEKTROMETER BERBASIS MIKROKONTROLER UNTUK KARAKTERISASI ARUS TEROBOSAN PADA MOSFET TESIS
SISTEM ELEKTROMETER BERBASIS MIKROKONTROLER
UNTUK KARAKTERISASI ARUS TEROBOSAN PADA MOSFET
TESIS
Karya tulis sebagai salah satu syarat
Untuk memperoleh gelar Magister dari
Institut Teknologi Bandung
Oleh
MUHAMMAD MIFTAHUL MUNIR
NIM: 20203018
DEPARTEMEN FISIKA
FAKULTAS MATEMATIKA DAN ILMU PENGETAHUAN ALAM
INSTITUT TEKNOLOGI BANDUNG
2005
SISTEM ELEKTROMETER BERBASIS MIKROKONTROLER
UNTUK KARAKTERISASI ARUS TEROBOSAN PADA MOSFET
Oleh
Muhammad Miftahul Munir
NIM: 20203018
Menyetujui
Pembimbing
Dr. Eng. Khairurrijal, M.Si.
NIP: 131 967 089
ABSTRAK
SISTEM ELEKTROMETER BERBASIS MIKROKONTROLER
UNTUK KARAKTERISASI ARUS TEROBOSAN PADA MOSFET
Oleh
Muhammad Miftahul Munir
NIM: 20203018
Elektrometer arus yang biasanya digunakan untuk mengukur sangat rendah pada range
pengukuran miliampere sampai dengan picoampere bahkan femtoampere banyak diaplikasikan
pada bidang berbeda seperti spektroskopi massa, akselerator, nuklir, vakum, atmosfer,
pengukuran optik dan eksperimen semikonduktor. Pada tesis ini sistem elektrometer berbasis
mikrokontroler yang terdiri atas komputer, antamuka RS232, mikrokontroler 8 bit C8051F006
dari Silicon Laboratories, DAC 12 bit, pengkondisi sinyal, pengali, fixture, penguat logaritmik
LOG112 dari Burr-Brown dan ADC 12 bit telah dikembangkan dan dikalibrasi menggunakan
kalibrator seri 5100B dari Fluke Corporation. Sistem elektrometer ini dapat mengukur arus pada
range 100 pA sampai dengan 14 mA dan sumber tegangan dapat diatur dari 0 Volt sampai
dengan 9.6 Volt. MOSFET tipe-n BS170 dan tipe-p BS250 dikarakterisasi menggunakan sistem
pengukuran ini. Hasil pengukuran menunjukkan karakteristik arus-tegangan menggunakan
elektrometer ini hasilnya sangat mirip dibandingkan dengan hasil karakterisasi menggunakan
HP4140B pA meter/DC voltage source dari Hewlett-Packard.
i
ABSTRACT
MICROCONTROLLER BASED ELECTROMETER SYSTEM
FOR CHARACTERIZING TUNNELING CURRENT IN MOSFET
By
Muhammad Miftahul Munir
NIM: 20203018
A current electrometer, which is commonly used for measuring very low currents in the range of
milliamperes down to picoamperes even femtoamperes, finds applications in many diverse areas
such as mass spectroscopy, particle accelerators, ultrahigh vacuum technology, photometric
measurements, atmospheric research, and semiconductor measurement. In this thesis
microcontroller based electrometer system consisting of a computer, an RS232 interface, the
Silicon Laboratories C8051F006 8-bit microcontroller, a 12-bit DAC, signal conditioners, a
multiplier, a 12-bit ADC, a fixture, and the Burr-Brown LOG112 logarithmic amplifier was
developed and calibrated by using the Fluke 5100B series calibrator. This electrometer system
is capable of measuring currents from 100 pA up to 14 mA and a programmable voltage source
in the range of 0 to 9.6 volts The BS170 n-channel MOSFET and The BS250 p-channel
MOSFET was characterized by the developed measurement system. It was shown that the I-V
characteristics obtained by the developed measurement system are comparable to those measured
by the Hewlett-Packard HP4140B pA meter/DC voltage source.
ii
PEDOMAN PENGGUNAAN TESIS
Tesis S2 yang tidak dipublikasikan terdaftar dan tersedia di Perpustakaan Institut Teknologi
Bandung dan terbuka untuk umum dengan ketentuan bahwa hak cipta ada pada pengarang.
Referensi kepustakaan diperkenankan dicatat, tetapi pengutipan atau peringkasan hanya dapat
dilakukan seizin pengarang dan harus disertai dengan kebiasaan ilmiah untuk menyebutkan
sumbernya.
Memperbanyak atau menerbitkan sebagian atau seluruh tesis haruslah seizin Direktur Program
Pascasarjana, Institut Teknologi Bandung.
Perpustakaan yang meminjam tesis ini untuk keperluan anggotanya harus mengisi nama dan
tanda tangan peminjam dan tanggal pinjam
iii
KATA PENGANTAR
Segala puji dan syukur penulis panjatkan kehadirat Allah SWT, karena dengan kuasa, kehendak
serta karunia-Nya penulis dapat menyelesaikan tesis ini.
Tesis ini ditulis sebagai persyaratan kelulusan program Magister pada Departemen Fisika Institut
Teknologi Bandung dan merupakan laporan atas diselesaikannya penelitian dengan judul
“Sistem Elektrometer Berbasis Mikrokontroler untuk Karakterisasi Arus Terobosan pada
MOSFET”.
Penulis menyadari bahwa dalam penulisan tesis ini masih banyak terdapat kekurangan. Oleh
karena itu saran dan kritik yang membangun akan penulis terima dengan senang hati. Akhir kata
penulis berharap agar tesis ini bermanfaat, khususnya bagi penulis maupun pihak-pihak yang
berkepentingan.
Bandung, Juni 2005
Penulis
iv
UCAPAN TERIMA KASIH
Dengan mengucap puji dan syukur ke hadirat Allah Yang Maha Agung, tidak lupa
penulis juga mengucapkan terima kasih kepada pihak-pihak yang membantu terselesaikannya
tesis ini :
x
Bapak Dr. Eng. Khairurrijal, M.Si., selaku dosen pembimbing yang senantiasa
mengarahkan, memotivasi dan membimbing selama penulis menyelesaikan S1 dan S2,
serta atas segala bantuannya yang sangat banyak baik materi maupun non materi. Mudahmudahan Allah SWT memberikan balasan yang berlipat ganda, memberikan rahmat dan
keberkahan kepada beliau dan keluargnya.
x
Bapak Dr. Sukirno, atas motivasi, pengajaran-pengajarannya, bantuan, serta kesediannya
menjadi dosen penguji.
x
Bapak Dr. Abdul Waris selaku dosen penguji dan atas ilmu-ilmu yang telah
disampaikannya.
x
Bapak Dr. Ing. Mitra Djamal, Bapak Dr. Zaki Su’ud, Bapak Dr. Maman Budiman beserta
seluruh staf pengajar Departemen Fisika khususnya yang tergabung dalam KBK
instrumentasi.
x
Institut Teknologi Bandung atas segala fasilitas dan beasiswa voucher yang diberikan
sehingga penulis dapat menyelesaikan S2 dengan baik dan lancar.
x
Ibu, adik dan saudara-saudara tercinta yang senantiasa tidak henti-hentinya memberi
support, do’a, kasih sayang kepada penyusun sejak kecil.
x
Almarhum Ayah, mudah-mudahan diampuni segala dosanya dan diterima disisi-Nya.
x
Teman-teman Pink House Amrih atas semua bantuannya yang sangat banyak, DSM
teman baik penulis sejak kecil, doni, widi dan rudi.
x
Rekan tim ELKAHFI yang sangat berkesan, Asep Suhendi dan Hendrayana Thaha atas
semua bantuannya yang sangat banyak.
x
Teman-teman Lab Elka Indra Chandra, Suryadi, Rijal Asshidiqi, Cahyo, Ismadi, Ivan,
Sandi, Aris, Maria, Emil, Rahmat, Arif, Johan, Marshandy dan teman-teman satu lab
lainnya.
x
Rekan-rekan S2 Syarif Riyadi, Umiatin, Topan, Rasih, Ardian, P’Zulhendri, P’Saumi,
P’Odan, Rozi serta rekan-rekan S2 lainnya.
v
x
P’Ohin, P’Dadang, P’Yeye, P’Daryat, P’ Dede dan seluruh karyawan Departemen Fisika
ITB.
x
Semua pihak yang telah membantu yang tidak dapat dituliskan namanya satu persatu.
vi
DAFTAR ISI
ABSTRAK ·····························································································································
i
ABSTRACT···························································································································
ii
PEDOMAN PENGGUNAAN TESIS ····················································································
iii
KATA PENGANTAR············································································································
iv
UCAPAN TERIMAKASIH ···································································································
v
DAFTAR ISI··························································································································
vii
DAFTAR GAMBAR ·············································································································
ix
BAB I
PENDAHULUAN
1.1
Latar Belakang dan Rumusan Masalah ··················································
1
1.1.1
Latar belakang ·······················································································
1
1.1.2
Rumusan masalah ··················································································
2
1.2
Ruang Lingkup Kajian ···········································································
3
1.3
Tujuan Penulisan····················································································
3
1.4
Metodologi Penelitian ············································································
3
1.5
Sistematika Pembahasan ········································································
3
BAB II TEORI DASAR SISTEM ELEKTROMETER PENGUKUR KARAKTERISTIK
ARUS-TEGANGAN
2.1
Elektrometer ··························································································
6
2.1.1
Dasar penguat logaritkmik ·····································································
6
2.1.2
Penguat logaritmik dengan pengkompensasi suhu ·································
8
2.1.3
Penguat logaritmik menggunakan dua buah transistor identik ··············
9
2.2
Mikrokontroler·······················································································
11
2.3
ADC (Analog to Digital Converter)·······················································
11
2.4
Prinsip Kerja DAC (Digital to Analog Converter) ·································
11
2.5
Arus Terobosan pada MOSFET (Metal-Oxide-Semiconductor Field-Effect
Transistor) ·····························································································
12
vii
BAB III PERANCANGAN DAN IMPLEMENTASI ELEKTROMETER BERBASIS
MIKROKONTROLER
3.1
Perancangan dan Implementasi Perangkat Keras ···································
15
3.1.1
Perancangan dan implementasi elektrometer ·········································
16
3.1.2
Error pada penguat logaritmik································································
17
3.1.3
Memperluas range pengukuran arus·······················································
19
3.1.4
Pemilihan dan implementasi mikrokontroler··········································
21
3.1.5
Implementasi sumber tegangan terprogram (programmable voltage
source) ···································································································
3.1.6
22
Implementasi ADC (analog to digital converter) dan pengkondisi
sinyal······································································································
24
3.1.7
Sistem antarmuka···················································································
25
3.2
Perancangan dan Implementasi Perangkat Lunak ·································
26
BAB IV PENGUJIAN ALAT DAN ANALISIS DATA
BAB V
4.1
Kalibrasi Sistem Elektrometer ······························································
28
4.1.1
Kalibrasi DAC (digital to analog converter)··········································
28
4.1.2
Kalibrasi ADC (analog to digital converter)··········································
31
4.1.3
Kalibrasi elektrometer ···········································································
34
4.2
Pengujian Sistem Elektrometer ······························································
37
4.2.1
Pengujian DAC (digital to analog converter) ········································
37
4.2.2
Pengujian ADC (analog to digital converter) ········································
38
4.2.3
Pengujian sistem ADC dan DAC ···························································
39
4.2.4
Pengujian sistem pengukuran arus dengan elektrometer ························
40
4.3
Hasil Pengukuran Karakteristik Arus-Tegangan Arus Terobosan
pada MOSFET (Metal Oxide Semiconductor Field Efect Transistor)····
42
4.3.1
Karakteristik arus-tegangan arus terobosan pada MOSFET tipe-p·········
44
4.3.2
Karakteristik arus-tegangan arus terobosan pada MOSFET tipe-n·········
45
KESIMPULAN DAN SARAN
5.1
Kesimpulan ····························································································
47
5.2
Saran ······································································································
47
DAFTAR PUSTAKA·············································································································
48
viii
DAFTAR GAMBAR
Gambar II.1.
Diagram blok sistem elektrometer pengukur karakteristik arus-tegangan ····
5
Gambar II.2.
Rangkaian dasar penguat logaritmik ····························································
7
Gambar II.3.
Rangkaian penguat logaritmik dengan pengkompensasi suhu······················
8
Gambar II.4.
Rangkaian penguat logaritmik menggunakan dua buah transistor identik····
10
Gambar II.5.
DAC 4 bit·····································································································
12
Gambar II.6.
Diagram struktur dari MOS n+ poly-Si pada kondisi flat-band ···············
13
Gambar II.7.
Arus terobosan terukur dan berdasarkan perhitungan menggunakan
hubungan dispersi non-parabolic E-k ··························································
14
Gambar III.1.
Diagram blok sistem elektrometer berbasis mikrokontroler·························
16
Gambar III.2.
Rangkaian penguat logaritmik dalam LOG112 ············································
17
Gambar III.3.
Persen error terhadap keluaran skala penuh dalam range pengukuran
5 dekade·······································································································
Gambar III.4
19
Persen error terhadap keluaran skala penuh dalam range pengukuran
7,5 dekade ···································································································
19
Gambar III.5.
Rangkaian pembagi arus untuk memperluas daerah pengukuran ·················
20
Gambar III.6.
Arsitektur mikrokontroler C8051F006 ·······················································
22
Gambar III.7.
Diagram blok DAC 12 bit dalam mikrokontroler C8051F006 ····················
23
Gambar III.8.
Rangkaian pengali (multiplier) dan penyangga ( buffer) ······························
24
Gambar III.9.
Diagram blok ADC 12 bit dalam mikrokontroler C8051F006 ····················
24
Gambar III.10. Rangkaian pengkondisi sinyal yang menghubungkan elektrometer dan
ADC·············································································································
25
Gambar III.11. Diagram alir program mikrokontroler ··························································
26
Gambar III.12. Diagram alir program komputer···································································
27
Gambar IV.1.
Diagram blok proses kalibrasi DAC ····························································
28
Gambar IV.2.
Grafik fungsi transfer konversi digital ke analog pada kalibrasi DAC ·········
29
Gambar IV.3.
Grafik selisih antara fungsi transfer ideal dengan fungsi transfer terukur
pada kalibrasi DAC······················································································
30
Gambar IV.4.
Grafik koreksi fungsi transfer DAC ·····························································
31
Gambar IV.5.
Diagram blok proses kalibrasi ADC ····························································
32
ix
Gambar IV.6.
Grafik fungsi transfer konversi analog ke digital pada kalibrasi ADC ·········
Gambar IV.7.
Grafik selisih antara fungsi transfer ideal dengan fungsi transfer terukur
32
pada kalibrasi ADC······················································································
33
Gambar IV.8.
Grafik koreksi fungsi transfer ADC ·····························································
33
Gambar IV.9.
Diagram blok proses kalibrasi elektrometer untuk arus 10 ȝA sampai
dengan 3,5 mA·····························································································
34
Gambar IV.10. Diagram blok proses kalibrasi elektrometer untuk arus 100 pA sampai
dengan 10 ȝA·······························································································
35
Gambar IV.11. Grafik fungsi transfer konversi digital ke analog pada kalibrasi
elektrometer ·································································································
35
Gambar IV.12. Grafik selisih antara fungsi transfer ideal dengan fungsi transfer terukur
pada kalibrasi elektrometer ··········································································
36
Gambar IV.13. Grafik koreksi fungsi transfer elektrometer··················································
37
Gambar IV.14. Grafik kesalahan pengukuran DAC ·····························································
38
Gambar IV.15. Grafik kesalahan pengukuran ADC ·····························································
38
Gambar IV.16. Digram blok proses pengujian sistem DAC dan ADC ·································
39
Gambar IV.17. Grafik kesalahan total pengukuran sistem DAC dan ADC···························
40
Gambar IV.18. Diagram blok proses pengujian sistem pengukuran arus dengan
elektrometer ·································································································
40
Gambar IV.19. Grafik kesalahan sistem pengukuran arus untuk range pengukuran
7,5 dekade····································································································
41
Gambar IV.20. Grafik kesalahan sistem pengukuran arus untuk range pengukuran
5 dekade·······································································································
42
Gambar IV.21. Grafik konfigurasi pengukuran karakteristik arus-tegangan arus terobosan
pada MOSFET tipe-p panjar maju dan MOSFET tipe-n panjar mundur ······
43
Gambar IV.22. Grafik konfigurasi pengukuran karakteristik arus-tegangan arus terobosan
pada MOSFET tipe-p panjar mundur dan MOSFET tipe-n panjar maju ······
44
Gambar IV.23. Grafik arus-tegangan arus terobosan pada MOSFET tipe BS250 panjar
maju ·············································································································
45
Gambar IV.24. Grafik arus-tegangan arus terobosan pada MOSFET tipe BS250 panjar
mundur·········································································································
45
x
Gambar IV.25. Grafik arus-tegangan arus terobosan pada MOSFET tipe BS170 panjar
maju ·············································································································
46
Gambar IV.26. Grafik arus-tegangan arus terobosan pada MOSFET tipe BS170 panjar
mundur·········································································································
46
xi
UNTUK KARAKTERISASI ARUS TEROBOSAN PADA MOSFET
TESIS
Karya tulis sebagai salah satu syarat
Untuk memperoleh gelar Magister dari
Institut Teknologi Bandung
Oleh
MUHAMMAD MIFTAHUL MUNIR
NIM: 20203018
DEPARTEMEN FISIKA
FAKULTAS MATEMATIKA DAN ILMU PENGETAHUAN ALAM
INSTITUT TEKNOLOGI BANDUNG
2005
SISTEM ELEKTROMETER BERBASIS MIKROKONTROLER
UNTUK KARAKTERISASI ARUS TEROBOSAN PADA MOSFET
Oleh
Muhammad Miftahul Munir
NIM: 20203018
Menyetujui
Pembimbing
Dr. Eng. Khairurrijal, M.Si.
NIP: 131 967 089
ABSTRAK
SISTEM ELEKTROMETER BERBASIS MIKROKONTROLER
UNTUK KARAKTERISASI ARUS TEROBOSAN PADA MOSFET
Oleh
Muhammad Miftahul Munir
NIM: 20203018
Elektrometer arus yang biasanya digunakan untuk mengukur sangat rendah pada range
pengukuran miliampere sampai dengan picoampere bahkan femtoampere banyak diaplikasikan
pada bidang berbeda seperti spektroskopi massa, akselerator, nuklir, vakum, atmosfer,
pengukuran optik dan eksperimen semikonduktor. Pada tesis ini sistem elektrometer berbasis
mikrokontroler yang terdiri atas komputer, antamuka RS232, mikrokontroler 8 bit C8051F006
dari Silicon Laboratories, DAC 12 bit, pengkondisi sinyal, pengali, fixture, penguat logaritmik
LOG112 dari Burr-Brown dan ADC 12 bit telah dikembangkan dan dikalibrasi menggunakan
kalibrator seri 5100B dari Fluke Corporation. Sistem elektrometer ini dapat mengukur arus pada
range 100 pA sampai dengan 14 mA dan sumber tegangan dapat diatur dari 0 Volt sampai
dengan 9.6 Volt. MOSFET tipe-n BS170 dan tipe-p BS250 dikarakterisasi menggunakan sistem
pengukuran ini. Hasil pengukuran menunjukkan karakteristik arus-tegangan menggunakan
elektrometer ini hasilnya sangat mirip dibandingkan dengan hasil karakterisasi menggunakan
HP4140B pA meter/DC voltage source dari Hewlett-Packard.
i
ABSTRACT
MICROCONTROLLER BASED ELECTROMETER SYSTEM
FOR CHARACTERIZING TUNNELING CURRENT IN MOSFET
By
Muhammad Miftahul Munir
NIM: 20203018
A current electrometer, which is commonly used for measuring very low currents in the range of
milliamperes down to picoamperes even femtoamperes, finds applications in many diverse areas
such as mass spectroscopy, particle accelerators, ultrahigh vacuum technology, photometric
measurements, atmospheric research, and semiconductor measurement. In this thesis
microcontroller based electrometer system consisting of a computer, an RS232 interface, the
Silicon Laboratories C8051F006 8-bit microcontroller, a 12-bit DAC, signal conditioners, a
multiplier, a 12-bit ADC, a fixture, and the Burr-Brown LOG112 logarithmic amplifier was
developed and calibrated by using the Fluke 5100B series calibrator. This electrometer system
is capable of measuring currents from 100 pA up to 14 mA and a programmable voltage source
in the range of 0 to 9.6 volts The BS170 n-channel MOSFET and The BS250 p-channel
MOSFET was characterized by the developed measurement system. It was shown that the I-V
characteristics obtained by the developed measurement system are comparable to those measured
by the Hewlett-Packard HP4140B pA meter/DC voltage source.
ii
PEDOMAN PENGGUNAAN TESIS
Tesis S2 yang tidak dipublikasikan terdaftar dan tersedia di Perpustakaan Institut Teknologi
Bandung dan terbuka untuk umum dengan ketentuan bahwa hak cipta ada pada pengarang.
Referensi kepustakaan diperkenankan dicatat, tetapi pengutipan atau peringkasan hanya dapat
dilakukan seizin pengarang dan harus disertai dengan kebiasaan ilmiah untuk menyebutkan
sumbernya.
Memperbanyak atau menerbitkan sebagian atau seluruh tesis haruslah seizin Direktur Program
Pascasarjana, Institut Teknologi Bandung.
Perpustakaan yang meminjam tesis ini untuk keperluan anggotanya harus mengisi nama dan
tanda tangan peminjam dan tanggal pinjam
iii
KATA PENGANTAR
Segala puji dan syukur penulis panjatkan kehadirat Allah SWT, karena dengan kuasa, kehendak
serta karunia-Nya penulis dapat menyelesaikan tesis ini.
Tesis ini ditulis sebagai persyaratan kelulusan program Magister pada Departemen Fisika Institut
Teknologi Bandung dan merupakan laporan atas diselesaikannya penelitian dengan judul
“Sistem Elektrometer Berbasis Mikrokontroler untuk Karakterisasi Arus Terobosan pada
MOSFET”.
Penulis menyadari bahwa dalam penulisan tesis ini masih banyak terdapat kekurangan. Oleh
karena itu saran dan kritik yang membangun akan penulis terima dengan senang hati. Akhir kata
penulis berharap agar tesis ini bermanfaat, khususnya bagi penulis maupun pihak-pihak yang
berkepentingan.
Bandung, Juni 2005
Penulis
iv
UCAPAN TERIMA KASIH
Dengan mengucap puji dan syukur ke hadirat Allah Yang Maha Agung, tidak lupa
penulis juga mengucapkan terima kasih kepada pihak-pihak yang membantu terselesaikannya
tesis ini :
x
Bapak Dr. Eng. Khairurrijal, M.Si., selaku dosen pembimbing yang senantiasa
mengarahkan, memotivasi dan membimbing selama penulis menyelesaikan S1 dan S2,
serta atas segala bantuannya yang sangat banyak baik materi maupun non materi. Mudahmudahan Allah SWT memberikan balasan yang berlipat ganda, memberikan rahmat dan
keberkahan kepada beliau dan keluargnya.
x
Bapak Dr. Sukirno, atas motivasi, pengajaran-pengajarannya, bantuan, serta kesediannya
menjadi dosen penguji.
x
Bapak Dr. Abdul Waris selaku dosen penguji dan atas ilmu-ilmu yang telah
disampaikannya.
x
Bapak Dr. Ing. Mitra Djamal, Bapak Dr. Zaki Su’ud, Bapak Dr. Maman Budiman beserta
seluruh staf pengajar Departemen Fisika khususnya yang tergabung dalam KBK
instrumentasi.
x
Institut Teknologi Bandung atas segala fasilitas dan beasiswa voucher yang diberikan
sehingga penulis dapat menyelesaikan S2 dengan baik dan lancar.
x
Ibu, adik dan saudara-saudara tercinta yang senantiasa tidak henti-hentinya memberi
support, do’a, kasih sayang kepada penyusun sejak kecil.
x
Almarhum Ayah, mudah-mudahan diampuni segala dosanya dan diterima disisi-Nya.
x
Teman-teman Pink House Amrih atas semua bantuannya yang sangat banyak, DSM
teman baik penulis sejak kecil, doni, widi dan rudi.
x
Rekan tim ELKAHFI yang sangat berkesan, Asep Suhendi dan Hendrayana Thaha atas
semua bantuannya yang sangat banyak.
x
Teman-teman Lab Elka Indra Chandra, Suryadi, Rijal Asshidiqi, Cahyo, Ismadi, Ivan,
Sandi, Aris, Maria, Emil, Rahmat, Arif, Johan, Marshandy dan teman-teman satu lab
lainnya.
x
Rekan-rekan S2 Syarif Riyadi, Umiatin, Topan, Rasih, Ardian, P’Zulhendri, P’Saumi,
P’Odan, Rozi serta rekan-rekan S2 lainnya.
v
x
P’Ohin, P’Dadang, P’Yeye, P’Daryat, P’ Dede dan seluruh karyawan Departemen Fisika
ITB.
x
Semua pihak yang telah membantu yang tidak dapat dituliskan namanya satu persatu.
vi
DAFTAR ISI
ABSTRAK ·····························································································································
i
ABSTRACT···························································································································
ii
PEDOMAN PENGGUNAAN TESIS ····················································································
iii
KATA PENGANTAR············································································································
iv
UCAPAN TERIMAKASIH ···································································································
v
DAFTAR ISI··························································································································
vii
DAFTAR GAMBAR ·············································································································
ix
BAB I
PENDAHULUAN
1.1
Latar Belakang dan Rumusan Masalah ··················································
1
1.1.1
Latar belakang ·······················································································
1
1.1.2
Rumusan masalah ··················································································
2
1.2
Ruang Lingkup Kajian ···········································································
3
1.3
Tujuan Penulisan····················································································
3
1.4
Metodologi Penelitian ············································································
3
1.5
Sistematika Pembahasan ········································································
3
BAB II TEORI DASAR SISTEM ELEKTROMETER PENGUKUR KARAKTERISTIK
ARUS-TEGANGAN
2.1
Elektrometer ··························································································
6
2.1.1
Dasar penguat logaritkmik ·····································································
6
2.1.2
Penguat logaritmik dengan pengkompensasi suhu ·································
8
2.1.3
Penguat logaritmik menggunakan dua buah transistor identik ··············
9
2.2
Mikrokontroler·······················································································
11
2.3
ADC (Analog to Digital Converter)·······················································
11
2.4
Prinsip Kerja DAC (Digital to Analog Converter) ·································
11
2.5
Arus Terobosan pada MOSFET (Metal-Oxide-Semiconductor Field-Effect
Transistor) ·····························································································
12
vii
BAB III PERANCANGAN DAN IMPLEMENTASI ELEKTROMETER BERBASIS
MIKROKONTROLER
3.1
Perancangan dan Implementasi Perangkat Keras ···································
15
3.1.1
Perancangan dan implementasi elektrometer ·········································
16
3.1.2
Error pada penguat logaritmik································································
17
3.1.3
Memperluas range pengukuran arus·······················································
19
3.1.4
Pemilihan dan implementasi mikrokontroler··········································
21
3.1.5
Implementasi sumber tegangan terprogram (programmable voltage
source) ···································································································
3.1.6
22
Implementasi ADC (analog to digital converter) dan pengkondisi
sinyal······································································································
24
3.1.7
Sistem antarmuka···················································································
25
3.2
Perancangan dan Implementasi Perangkat Lunak ·································
26
BAB IV PENGUJIAN ALAT DAN ANALISIS DATA
BAB V
4.1
Kalibrasi Sistem Elektrometer ······························································
28
4.1.1
Kalibrasi DAC (digital to analog converter)··········································
28
4.1.2
Kalibrasi ADC (analog to digital converter)··········································
31
4.1.3
Kalibrasi elektrometer ···········································································
34
4.2
Pengujian Sistem Elektrometer ······························································
37
4.2.1
Pengujian DAC (digital to analog converter) ········································
37
4.2.2
Pengujian ADC (analog to digital converter) ········································
38
4.2.3
Pengujian sistem ADC dan DAC ···························································
39
4.2.4
Pengujian sistem pengukuran arus dengan elektrometer ························
40
4.3
Hasil Pengukuran Karakteristik Arus-Tegangan Arus Terobosan
pada MOSFET (Metal Oxide Semiconductor Field Efect Transistor)····
42
4.3.1
Karakteristik arus-tegangan arus terobosan pada MOSFET tipe-p·········
44
4.3.2
Karakteristik arus-tegangan arus terobosan pada MOSFET tipe-n·········
45
KESIMPULAN DAN SARAN
5.1
Kesimpulan ····························································································
47
5.2
Saran ······································································································
47
DAFTAR PUSTAKA·············································································································
48
viii
DAFTAR GAMBAR
Gambar II.1.
Diagram blok sistem elektrometer pengukur karakteristik arus-tegangan ····
5
Gambar II.2.
Rangkaian dasar penguat logaritmik ····························································
7
Gambar II.3.
Rangkaian penguat logaritmik dengan pengkompensasi suhu······················
8
Gambar II.4.
Rangkaian penguat logaritmik menggunakan dua buah transistor identik····
10
Gambar II.5.
DAC 4 bit·····································································································
12
Gambar II.6.
Diagram struktur dari MOS n+ poly-Si pada kondisi flat-band ···············
13
Gambar II.7.
Arus terobosan terukur dan berdasarkan perhitungan menggunakan
hubungan dispersi non-parabolic E-k ··························································
14
Gambar III.1.
Diagram blok sistem elektrometer berbasis mikrokontroler·························
16
Gambar III.2.
Rangkaian penguat logaritmik dalam LOG112 ············································
17
Gambar III.3.
Persen error terhadap keluaran skala penuh dalam range pengukuran
5 dekade·······································································································
Gambar III.4
19
Persen error terhadap keluaran skala penuh dalam range pengukuran
7,5 dekade ···································································································
19
Gambar III.5.
Rangkaian pembagi arus untuk memperluas daerah pengukuran ·················
20
Gambar III.6.
Arsitektur mikrokontroler C8051F006 ·······················································
22
Gambar III.7.
Diagram blok DAC 12 bit dalam mikrokontroler C8051F006 ····················
23
Gambar III.8.
Rangkaian pengali (multiplier) dan penyangga ( buffer) ······························
24
Gambar III.9.
Diagram blok ADC 12 bit dalam mikrokontroler C8051F006 ····················
24
Gambar III.10. Rangkaian pengkondisi sinyal yang menghubungkan elektrometer dan
ADC·············································································································
25
Gambar III.11. Diagram alir program mikrokontroler ··························································
26
Gambar III.12. Diagram alir program komputer···································································
27
Gambar IV.1.
Diagram blok proses kalibrasi DAC ····························································
28
Gambar IV.2.
Grafik fungsi transfer konversi digital ke analog pada kalibrasi DAC ·········
29
Gambar IV.3.
Grafik selisih antara fungsi transfer ideal dengan fungsi transfer terukur
pada kalibrasi DAC······················································································
30
Gambar IV.4.
Grafik koreksi fungsi transfer DAC ·····························································
31
Gambar IV.5.
Diagram blok proses kalibrasi ADC ····························································
32
ix
Gambar IV.6.
Grafik fungsi transfer konversi analog ke digital pada kalibrasi ADC ·········
Gambar IV.7.
Grafik selisih antara fungsi transfer ideal dengan fungsi transfer terukur
32
pada kalibrasi ADC······················································································
33
Gambar IV.8.
Grafik koreksi fungsi transfer ADC ·····························································
33
Gambar IV.9.
Diagram blok proses kalibrasi elektrometer untuk arus 10 ȝA sampai
dengan 3,5 mA·····························································································
34
Gambar IV.10. Diagram blok proses kalibrasi elektrometer untuk arus 100 pA sampai
dengan 10 ȝA·······························································································
35
Gambar IV.11. Grafik fungsi transfer konversi digital ke analog pada kalibrasi
elektrometer ·································································································
35
Gambar IV.12. Grafik selisih antara fungsi transfer ideal dengan fungsi transfer terukur
pada kalibrasi elektrometer ··········································································
36
Gambar IV.13. Grafik koreksi fungsi transfer elektrometer··················································
37
Gambar IV.14. Grafik kesalahan pengukuran DAC ·····························································
38
Gambar IV.15. Grafik kesalahan pengukuran ADC ·····························································
38
Gambar IV.16. Digram blok proses pengujian sistem DAC dan ADC ·································
39
Gambar IV.17. Grafik kesalahan total pengukuran sistem DAC dan ADC···························
40
Gambar IV.18. Diagram blok proses pengujian sistem pengukuran arus dengan
elektrometer ·································································································
40
Gambar IV.19. Grafik kesalahan sistem pengukuran arus untuk range pengukuran
7,5 dekade····································································································
41
Gambar IV.20. Grafik kesalahan sistem pengukuran arus untuk range pengukuran
5 dekade·······································································································
42
Gambar IV.21. Grafik konfigurasi pengukuran karakteristik arus-tegangan arus terobosan
pada MOSFET tipe-p panjar maju dan MOSFET tipe-n panjar mundur ······
43
Gambar IV.22. Grafik konfigurasi pengukuran karakteristik arus-tegangan arus terobosan
pada MOSFET tipe-p panjar mundur dan MOSFET tipe-n panjar maju ······
44
Gambar IV.23. Grafik arus-tegangan arus terobosan pada MOSFET tipe BS250 panjar
maju ·············································································································
45
Gambar IV.24. Grafik arus-tegangan arus terobosan pada MOSFET tipe BS250 panjar
mundur·········································································································
45
x
Gambar IV.25. Grafik arus-tegangan arus terobosan pada MOSFET tipe BS170 panjar
maju ·············································································································
46
Gambar IV.26. Grafik arus-tegangan arus terobosan pada MOSFET tipe BS170 panjar
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