Bias Circuit

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Unit 9. MOSFET Current Sources With the evolution of integrated circuits, it was necessary to reduce the number of resistors in the circuit, and the solution was the transistor current source. An added bonus was that the circuit was generally greatly improved as well. Here, the basic principle is introduced, followed by a discussion of the standard method of increasing the current output resistance with source degeneration. The application of a current-source configuration for balancing a differential amplifier stage is discussed.
9.1 Basic Current Source An example of a current source based on PMOS transistors is shown here in Fig. 9.1. It consists of the reference circuit, consisting of transistor M3 and bias resistor Rbias. The reference-circuit transistor is diode connected. The induced VSG3 = VSD3 is applied to the current-source transistor M2. Thus, the drain current, or current-source current of M2 is the mirror of the reference current. In an integrated circuit, any number of current sources can be referenced to the reference current or voltage. Current ratios are implemented with the selection of the relative gate widths of the transistors. Figure 9.1. PMOS current source. The current set up by the reference circuit of M3 and Rbias is mirrored as the current of M2. The design of the reference circuit is based on a dc solution to the reference current, ID3. The solution is obtained from the loop equation Equation 9.1 and transistor equation Equation 9.2 The current in M2 is Equation 9.3 where
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Copyright Library of Congress Catal
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National Improvements | Virtual Ins
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formulations, the results from Math
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Hardware and Software Requirements
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Chan0_out Pin 21 Chan0_in Pin 68 Gn
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LabVIEW VI Libraries and Project an
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1.1 Resistor Voltage Divider and MO
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1.3 Frequency Response of the Ampli
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At f = flo, . This, by definition,
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1.5 Exercises and Projects Project
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2.1 BJT and MOSFET Schematic Symbol
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2.2 Fundamentals of Signal Amplific
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2.3 Basic NMOS Common-Source Amplif
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Using (2.4), (2.5), (2.9), and (2.1
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Unit 3. Characterization of MOS Tra
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In electronic circuit applications,
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The output-characteristic equation
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Equation 3.11 From the data measure
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The input circuit loop equation (Fi
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which leads to the result (3.5), re
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Unit 4. Signal Conductance Paramete
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4.2 Transistor Variable Incremental
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4.3 Transconductance Parameter The
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4.4 Body-Effect Transconductance Pa
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4.5 Output Conductance Parameter Th
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With a 1 - V drop across RS and a 5
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By the nature of the load-line func
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Unit 5. Common-Source Amplifier Sta
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5.2 Amplifier Voltage Gain This dc
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etween the drain and source of the
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5.3 Linearity of the Gain of the Co
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where av Vds/Vgs and where the appr
Page 70 and 71: is attached directly to the gate. B
Page 72 and 73: 5.5 Design of a Basic Common-Source
Page 74 and 75: = VGSo - Vtno at the high and low e
Page 76 and 77: RG can be selected somewhat arbitra
Page 78 and 79: 5.7 Exercises and Projects Project
Page 80 and 81: 6.1 Grounded-Source Amplifier: Coup
Page 82 and 83: and Equation 6.6 Note that the "RC"
Page 84 and 85: 6.4 Load Coupling Capacitor The com
Page 87 and 88: 6.5 Summary of Equations MOSFET cou
Page 89 and 90: Unit 7. MOSFET Source-Follower Buff
Page 91 and 92: 7.2 Source-Follower Voltage Transfe
Page 93 and 94: 7.3 Body Effect and Source-Follower
Page 95 and 96: 7.4 Summary of Equations Threshold
Page 97 and 98: Unit 8. MOSFET Differential Amplifi
Page 99 and 100: 8.2 DC Imbalances In a real transis
Page 101 and 102: 8.3 Signal Voltage Gain of the Idea
Page 103 and 104: 8.4 Effect of the Bias Resistor on
Page 105 and 106: 8.5 Differential Voltage Gain Suppo
Page 107 and 108: 8.7 Voltage Gains Including Transis
Page 109 and 110: 8.7.2 Common-Gate Amplifier Stage T
Page 111 and 112: with RD1 = RD2 and gm1 = gm2. In th
Page 113 and 114: It follows that the gain for the in
Page 115 and 116: 8.9 Amplifier Gain with Differentia
Page 117 and 118: 8.11 Summary of Equations Rs = Ris2
Page 119: 8.12 Exercises and Projects Project
Page 123 and 124: 9.2 Current Source with Source Dege
Page 125 and 126: If the magnitude of the voltage acr
Page 127 and 128: Any slight possible difference in
Page 129 and 130: Unit 10. Common-Source Amplifier wi
Page 131 and 132: 10.2 Signal Voltage Gain The expres
Page 133 and 134: 10.3 Summary of Equations Output dr
Page 135 and 136: Unit 11. Operational Amplifiers wit
Page 137 and 138: 11.1.1 Voltage Gain of the Noninver
Page 139 and 140: This expression can be manipulated
Page 141 and 142: 11.3 Operational Amplifier Offset I
Page 143 and 144: where the approximation usually app
Page 145 and 146: where Avo is the amplifier gain at
Page 149 and 150: 12.1 Operational Amplifier Integrat
Page 151 and 152: This demonstrates that for the circ
Page 153 and 154: with a steady-state value of Vop. A
Page 155 and 156: Equation 12.25 A good estimate come
Page 159 and 160: 13.1 Combining NMOS and PMOS Circui
Page 161 and 162: 13.3 Stabilization of Signal Gain a
Page 163 and 164: An estimate of the new output volta
Page 165 and 166: This produces (9.9) from Ro = Vo/Io
Page 167 and 168: Equation 13.13 where 13.12 has been
Page 169 and 170: The open-loop transconductance is G
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Unit 14. Development of a Basic CMO
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14.2 Current-Source Output Resistan
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14.3 Current-Source Load for the Co
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14.4 Current-Source Load for the Di
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the node (exclusive of the separate
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14.5 Two-Stage Amplifier with Curre
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14.6 Output Buffer Stage It is evid
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Suppose that ID6 = 400 µA, W6 = 50
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Av and Ro are calculated once, usin
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Since the source follower of M1 has
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14.9 Summary of Equations CMRR = 1
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Unit A. Communicating with the Circ
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Place AI Acquire Waveform.vi in the
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Click from the Front Panel or Diagr
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Now go to the Diagram (under Menu W
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To complete connections to the term
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Now use the Edit Text Tool to edit
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on the left in the diagram . The Wh
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Figure A.15. Frame of Sequence Stru
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The transition regions are nonabrup
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during the oscilloscope measurement
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Unit B. Characterization of the Bip
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junction diodes, the current is lar
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common to the input and output and
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B.2 Base-Width Dependence on Juncti
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Figure B.8. Diodelike characteristi
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The minus sign comes from having as
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Figure B.10. Circuit for measuring
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B.5 Output Characteristics of BJT i
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After measuring the output characte
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B.6 SPICE Solution for IC versus VC
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B.7 Collector-Emitter Voltage and C
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B.8 DC as a Function of Collector C
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B.10 Summary of Equations Common-em
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Unit C. Common-Emitter Amplifier St
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The equation set above has three un
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The output-resistance parameter, ro
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of βDC as possible. Signal paramet
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Equation C.17 We note that the magn
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C.4 Accuracy of Transistor Gain Mea
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C.5 Effect of Finite Slope of the T
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It follows that for this case, f3dB
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C.7 Common-Emitter Amplifier with A
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Equation C.41 where IC IC(VCE), tha
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Applied voltage Vo sums up to Equat
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C.7.3 DC (Bias) of the NPN - PNP Am
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where Equation C.58 and Equation C.
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Equation C.67 The result is signifi
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The following form of the result pr
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This is equivalent to a unity-gain
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C.11 Summary of Circuit Equations B
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C.12 Exercises and Projects Project
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P1.1 Resistor Voltage-Divider Measu
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• Place AO Update Channel.vi in F
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• (Optional) To install the circu
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Procedure • Set your value of RG2
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• In the Diagram, we will add Get
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P1.4 Resistor Voltage Divider with
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• Now move the capacitor C2 = C1
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P2.1 NMOS Common-Source Circuit wit
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• In the Diagram (below), place,
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P2.2 NMOS Common-Source Amplifier w
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P2.3 Amplifier with Signal and Gain
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• Connect to FG1Chan.vi, the vari
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P3.1 SPICE Parameters and Pin Diagr
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P3.3 PMOS Transistor Use pins 6 (ga
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Procedure • Run PMOSlinear.vi and
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Procedure • Run PMOSparsub.vi wit
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Procedure • Run PMOSparam.vi to r
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Active Region Procedure • Install
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Laboratory Project 4. Characterizat
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P4.2 NMOS Transistor Use CD4007 pin
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P4.4 NMOS Parameters from the Trans
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P4.5 NMOS Lambda from the Transfer
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P4.6 NMOS Gamma SubVI Components No
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• Set RS. With NMOSgamsub.vi open
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• A file can be obtained from the
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P5.1 SPICE Equations and Pin Diagra
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P5.3 Amplifier Gain at One Bias Cur
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P5.4 Amplifier Gain versus Bias Cur
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Laboratory Project 6. PMOS Common-
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P6.2 SPICE PMOS and Circuit Equatio
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P6.4 Amplifier Gain LabVIEW Computa
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P6.5 Amplifier Frequency Response P
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P7.1 Chip Diagram and SPICE Equatio
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P7.3 Amplifier Gain at Optimum Bias
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P7.4 Optimum Bias Stability Test
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P7.5 Amplifier Frequency Response P
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Laboratory Project 8. NMOS Source-
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P8.2 Source-Follower DC Evaluation
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available for the next VI. It is us
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Laboratory Project 9. MOSFET Differ
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P9.2 DC Evaluation of the Single-Po
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P9.3 Determination of the PMOS Para
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Gains will be obtained from the gra
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• Run SweepSim.vi to obtain the d
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Laboratory Project 10. Current Mirr
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P10.2 Evaluation of the Current-Sou
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P10.4 Evaluation of the Bias Setup
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Laboratory Project 11. Operational
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P11.2 Bias Circuit Setup 1 Offset N
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P11.3 Opamp Offset Voltage Componen
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P11.4 Evaluation of the Bias Balanc
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VOH • Reset the Chan0_out Range,
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P11.6 Evaluation of the Gain with S
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P11.7 Determination of the Opamp Fr
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Laboratory Project 12. Operational
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P12.2 Opamp Integrator Components R
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Procedure • Turn off the power su
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Laboratory Project A. Communicating
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PA.2 Sending and Receiving Voltages
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Bipolar TABLE PA.2 0 to +5V 1.22 mV
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PA.5 Observing the Oscilloscope Out
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of the DAC. The steps are 2.44 mV f
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• The example here illustrates th
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Laboratory Project B. Characterizat
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PB.2 SPICE Equations SPICE Equation
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parameters nF and IS. • Connect C
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PB.4 DC versus the Collector Curren
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• Now open VI, IC_VCE.vi. Set the
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Laboratory Project C1. NPN Common-
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PC.2 DC Circuit Setup and Parameter
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PC.3 Amplifier Gain at One Bias Cur
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PC.4 Amplifier Gain versus Bias Cur
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• Run FreqResp.vi. Verify that in
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PC.6 SPICE Equations and Pin Diagra
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• Determine the value of VAF spec
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• Set the Run Mode switch to Set
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• Now reset VCC(init) and VBB(ini
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Bias Circuit

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