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アナログ・デジタル電子回路基礎
FUNDAMENTALS OF ANALOG AND DIGITAL CIRCUIT
能動素子 トランジスタの特性
Kazu. TAKASHIO
Exercise: Germanium Radio ! Simulate a germanium radio circuit..
Exercise: Germanium Radio ! Amplitude Modulation (AM)
! Modulation: Amplitude of carrier wave x Amplitude of modulation wave
! Amplitude modulation factor: m = (A - B)/(A + B) A: Peak of amplitude envelope curve B: Valley of amplitude envelope curve
! Input wave A ! Modulation wave: 10kHz (2.5mVp-p)
with 5mV offset voltage ! Carrier wave: 594kHz (NHK 1)
! Input wave B ! Modulation wave: 20kHz (2.5mVp-p)
with 5mV offset voltage ! Carrier wave: 954kHz (TBS)
Exercise: Germanium Radio ! Tuning circuit (LC parallel resonance circuit) ! At resonance frequency (fr = 1/(2π√(LC))) extremely high impedance..
! C1 = 276pF -> fr = 594kHz ! C1 for receiving TBS?? ! D1: Wave detection (detector) ! C1: Filtering out the carrier (LPF)
ゲルマニウムダイオード 受信アンテナ
信号電流
レシーバ
同調回路 (並列型)
Tuning Parameters ! Resonance frequency: fr = 1/(2π√(LC))
! fr = 594kHz,L = 260μH ! C1 ≒ 107pF
Observation of Waveform ! V(am),V(lc) and V(out)
Transistor ! The greatest invention of the 20th century
! J. Bardeen, W. Shockley and W. Brattain at AT&T Bell Labs, 1948 ! H. Uchida’s work at NHK STRL was first?.. ignored by GHQ??
! Commercialized device by TOKYO Tsushin Kogyo (current SONY), 1954 ! The first commercially successful transistor radio (TR-55), 1955
! Two uses (applications..) ! As an amplifier
! Current gain ! Voltage gain ! Power gain
! As a switch ! Logic gates
Transistor ! Junction transistor
! Three regions of doped semiconductors ! PNP type ! NPN type
! As a current amplifier ! The smaller current in the base acts as a "valve", controlling the larger current from collector to emitter..
Types of Transistors ! Bipolar transistor >> Current driven
! NPN transistor ! PNP transistor
! Unipolar transistor (field-effect transistor) >> Voltage driven ! Junction field-effect transistor (J-FET)
! N channel J-FET ! P channel J-FET
! Metal‒oxide‒semiconductor field-effect transistor (MOS-FET) ! N channel MOS-FET ! P channel MOS-FET
Transistor: Operations ! Switching
! As a high-speed relay.. ! Mechanical relay < 10Hz ! Transistor >> 100MHz
! High-voltage / high-current switching.. ! An output current of a microcomputer or a gate IC is about 20mA..
! A transistor or a MOS-FET attached to a microcomputer’s I/O port enables to drive a relay, solenoid, motor or super luminosity LED, or to control a power source..
! Amplification ! Operate a transistor in intermediate state between ON and OFF, and have it generating a large signal similar to an input signal..
Exercise in the Kickoff Class ! ex: Switching operation of a NPN Transistor
LTspice: Simulation ! Run simulation.. : [Run] icon ! Select a signal.. : VIN/VOUT/IB(Base current)
! Voltage Probe
! Current Probe
Switching Operation
PMOSトランジスタのスイッチング動作
S����G����D
! MOS (Metal Oxide Semiconductor) transistor ! 3 terminals: Source (S) / Drain (D) / Gate (G) ! Field-effect transistor (FET)
! Logic gates
! NOT ! NAND ! NOR
Logical Operation (Operator..) Input Output A out 0 1 1 0
Input Output A B Y 0 0 0 0 1 1 1 0 1 1 1 1
Logic Operation
Boolean Expression Circuit Symbol (MIL)
NOT A OR A + B AND A・B XOR A + B NOR A + B NAND A・B
Logical Operation (Operator..) Input Output
A B Y 0 0 0 0 1 0 1 0 0 1 1 1
Logic Operation
Boolean Expression Circuit Symbol (MIL)
NOT A OR A + B AND A・B XOR A + B NOR A + B NAND A・B
Input Output A B Y 0 0 0 0 1 1 1 0 1 1 1 0
Logical Operation (Operator..) Input Output
A B Y 0 0 1 0 1 0 1 0 0 1 1 0
Logic Operation
Boolean Expression Circuit Symbol (MIL)
NOT A OR A + B AND A・B XOR A + B NOR A + B NAND A・B
Input Output A B Y 0 0 1 0 1 1 1 0 1 1 1 0
Transistor Amplifiers ! Grounded-emitter transistor amplifier
! Most often-used transistor amplifier circuit ! Base input, collector output (inverted phase) ! Good power gain, but not so good frequency characteristics ! Fixed bias
エミッタ接地 ベース接地 コレクタ接地
負荷抵抗
直流削除用 直流 削除用
固定 バイアス用 電流帰還用
バイアス抵抗
バイパス コンデンサ
直流削除用
電流制御用 抵抗(負荷)
負荷抵抗
負荷抵抗 固定 バイアス用
直流削除用 直流 削除用
Transistor Amplifiers ! Grounded-base transistor amplifier
! Emitter input, collector output ! High power gain, 0dB current gain ! Two powered bias for current control on emitter.. ! Good frequency characteristics
エミッタ接地 ベース接地 コレクタ接地
負荷抵抗
直流削除用 直流 削除用
固定 バイアス用 電流帰還用
バイアス抵抗
バイパス コンデンサ
直流削除用
電流制御用 抵抗(負荷)
負荷抵抗
負荷抵抗 固定 バイアス用
直流削除用 直流 削除用
Transistor Amplifiers ! Grounded-collector transistor amplifier (emitter follower)
! Base input, emitter output ! High current gain, 0dB voltage gain ! Good high-frequency property in over 100MHz.. ! Low output impedance
エミッタ接地 ベース接地 コレクタ接地
負荷抵抗
直流削除用 直流 削除用
固定 バイアス用 電流帰還用
バイアス抵抗
バイパス コンデンサ
直流削除用
電流制御用抵抗(負荷)
負荷抵抗
負荷抵抗 固定 バイアス用
直流削除用 直流 削除用
Transistor: Basic Characteristics ! DC amplification factor: hFE = IC / IB ! Base-emitter voltage: VBE = 0.6V ~ 0.7V (0.65V in normal) ! IC - VCE characteristics (static characteristics)
電源電圧
電源電圧/負荷抵抗
動作点
動作線
歪みが生じる
Grounded-Emitter Transistor Amplifier
VE
IE
IC
VC
VBE
VB
IB
Ibias
! Parameters ! Fixed bias for VB ! Current feedback bias with RE
! Calculation of resistance values ! Decide IC from the circuit spec.
>> ex. IC = 1mA ! Usually VE needs 0.5 - 2V for absorbing
the effect of temperature change.. >> ex. VE = 1.5V
! IB is quite small IC ≒ IE >> RE = VE / IC = 1.5kΩ
! VB = VE + VBE VBE = 0.65V >> VB = 1.5 + 0.65 = 2.15V
Grounded-Emitter Transistor Amplifier
VE
IE
IC
VC
VBE
VB
IB
Ibias
! Calculation of resistance values (contd.) ! Ibias should be define 10 times of IB (hFE of most transistors are
100 - 300, thus 1/10 - 1/30 of IC is appropriate).. >> ex. Ibias = 143μA
! Ibias >> IB RB2 = VB / Ibias >> RB2 = 2.15 / 140 ≒ 15kΩ >> RB1 = ... = 68kΩ
! Bypass capacitor CE ! Increase AC gain while maintaining
the temperature stability by RE.. ! Distortion increases in
proportion to the gain.. ! Gain depression in
low-frequency area >> ex. CE = 100μF
Grounded-Emitter Transistor Amplifier
VE
IE
IC
VC
VBE
VB
IB
Ibias
! Operating point of VC ! In case of no signal on CE
VC = VCC - RC IC ! RC = 4.7kΩ >> VC = 12 - 4.7k × 1m = 7.3V
! Voltage gain on AC amplification ! Inner resistances: rb,re,rc ! ZCE is quite small for AC signal..
vb = rb ib + re ie ! Replace “AC current gain hfe” as β..
ie = ib + βib = (1 + β) ib ! Input impedance Zie:
Zie = vb / ib = rb + (1 + β) re ! rb of Small signal transistor:
50 - 500Ω When the β is sufficiently-large Zie ≒ (1 + β) re ≒ βre
Grounded-Emitter Transistor Amplifier
VE
IE
IC
VC
VBE
VB
IB
Ibias
! Voltage gain on AC amplification (contd.) ! Voltage gain: Av = vout / vb ! vout = RC β ib and ib = vb / Zie
>> Av = vout / vb = βRC / (βre) = RC / re ! Emitter inner resistance: re
! Resistance in forward direction diode ! Determined by physical property
>> re ≒ (26 / IE [mA]) Ω
! Without CE ! Replace re with re + RE
>> Av = RC / (re + RE) ≒ RC / RE
Simulation ! Transistor 2N3904, collector current 1mA
Exercise: Circuit Evaluation ! Observe DC operation points in no signal case..
! DC bias point simulation ! In [LTspice directive] > [Analysis Cmd.] > [DC Bias Point] tab,
define “.op” and place on the schematic.. ! Operation points are saved in a log file (xxx.log).. ! Compare observed voltage values with expected values..
! Measure voltage gain from amplified waveform.. ! Transient analysis mode “.tran 10m” ! Measure amplitude of V(vout) and calculate gain..
! Observe distortion of waveform ! Transient analysis mode “.tran 100m” ! In waveform window, [View] > [FFT] ! Compare the level of basic wave and second order harmonics [dB].
Exercise: Circuit Evaluation ! Observe frequency characteristics of voltage gain..
! AC analysis mode “.ac dec 100 1 100MEG” ! Frequency characteristics of output voltage
! Display in dB (dBV) ! Display voltage gain with [Add Trace] command..
! Output voltage / input voltage ! R3 (after VIN): Inner resistance of power source
! Evaluate cutoff frequencies in low-frequency area and high-frequency area.. ! Cutoff frequency: -3dB (1/√2) point
! Bypass condenser and frequency characteristics ! Replace value of C2 with “{Cbp}”.. ! Parametric sweep analysis “.step param Cbp 20u 200u 20u” ! Observe the behavior of cutoff frequency..
Exercise: Circuit Evaluation ! Question
! Report the result of simulations..
! Submit to SFC-SFS ! Deadline: 23rd Oct. 23:59