CMOS Optical Preamplifier Design Using Graphical Circuit Analysis

More documents

Recommendations

Info

5.2 Developing an Analytic <strong>Circuit</strong> Model 126 effective transconductance of the transistor. Second, we can identify a region in the design space where the higher poles are in close enough proximity to the dominant- pole to have an effect on the overall preamplifier bandwidth. Figure 5.16 shows a plot of the simulated bandwidth from SPICE as well as the pole locations derived from the analytic expressions. The SPICE results merely indicate a path of slightly enhanced bandwidth that is marked by the arrow; the analytic results, however, pro- vide us with the underlying reason for the observation. Third, although SPICE can- not predict the effect of power dissipation on bandwidth, Equation (5.26) points out that the power dissipation — as represented by the sum of transconductances and gm3 — is secondary to the ratio of gm2 and gm3 , represented by the current mirror gain , in determining the dominant pole frequency. Furthermore, we can infer from Equation (5.26) that the sensitivity of the bandwidth to is greatly affected by the capacitive load present at the input and output of the preamplifier. Fourth, in fiber-optic applications where the input capacitance is much smaller, and in cases where is greater than two (6 dB) or so, Equation (5.26) can be simpli- fied to K cm ω p1 ≈ --------------------------------- . ( CL + C f )Rf We see in this situation that significant speed can be gained through increasing K cm K cm K cm . This is illustrated in Figure 5.17 in which the input capacitance has been reduced from 2pF down to 100fF. 1 We see that surface contour has changed signifi- cantly from Figure 5.16. While this result can be inferred from studying Equation (5.22), there is no way to predict such changes from the original SPICE simulations. The observations described above are but a few of the design insights that can be gleaned from the design equations, but not from numeric simulation results. The contribution of DPI/SFG analysis to this process is in giving the designer the ability to break down the dynamic feedback mechanisms of any circuit in order to make small, isolated decisions and simplifications which, taken as a whole, produce sim- plified analytic expressions that capture the essence of the circuit. 1. Note that the bandwidth improvement is not as dramatic due to the effect which K cm has on C L . K cm g m2
Frequency (MHz) 500 450 400 350 300 250 200 150 100 50 0 0 5 R f (kΩ) 10 15 20 15 10 5.2 Developing an Analytic <strong>Circuit</strong> Model 127 5 0 −5 −10 Current Gain Kcm (dB) surface:ω p1 Figure 5.16 Plot of pole frequencies and simulated bandwidth vs. feedback resistance and current mirror gain. Pole frequencies(MHz) 900 800 700 600 500 400 300 200 100 0 0 R f (kΩ) 5 10 R f (kohms) 15 w p1 and w o vs. R f and Current Mirror Gain 20 15 surface:ω p1 10 5 0 −5 −10 Current 20*logGain (Gain) K 10 cm (dB) −15 ω o −15 −20 ring mesh - simulated bandwidth Figure 5.17 Plot of pole frequencies vs. feedback resistance and current mirror gain. ω o −20
Page 1 and 2:
CMOS Optical Preamplifier Design Us
Page 3 and 4:
To achieve low-voltage operation, w
Page 5 and 6:
Table of Contents CHAPTER 1 INTRODU
Page 7 and 8:
CHAPTER 1 1.1 OVERVIEW Introduction
Page 9 and 10:
Information Source Modulator Drive
Page 11 and 12:
1.2 Thesis Outline 5 [Ohhata,1999].
Page 13 and 14:
1.2 Thesis Outline 7 technique call
Page 15 and 16:
1.2 Thesis Outline 9 Detector in St
Page 17 and 18:
E e + - V bias 2.1 Photodetectors 1
Page 19 and 20:
Diode Capacitance (pF) Diode capaci
Page 21 and 22:
2.2 Optical Preamplifier Structures
Page 23 and 24:
2.3 Transimpedance Amplifier Design
Page 25 and 26:
Page 27 and 28:
I dc 2.3 Transimpedance Amplifier D
Page 29 and 30:
Page 31 and 32:
Source Figure 2.11 General structur
Page 33 and 34:
A = = For = 1V , the solution is v
Page 35 and 36:
The gain of the forward amplifier c
Page 37 and 38:
Feedback Analysis Using Return Rati
Page 39 and 40:
2.4 Circuit Analysis Techniques 33
Page 41 and 42:
2.5 An Overview of Signal-Flow Grap
Page 43 and 44:
1 x1 x2 2.5 An Overview of Signal-F
Page 45 and 46:
2.6 SUMMARY REFERENCES • ∆ k =
Page 47 and 48:
Symp. Circuits Systems, vol. 3, pp.
Page 49 and 50:
CHAPTER 3 New Transimpedance Amplif
Page 51 and 52:
3.1 A Differential Transimpedance A
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
3.2 A Feedback Topology for Ambient
Page 59 and 60:
3.2 A Feedback Topology for Ambient
Page 61 and 62:
Transimpedance (dBΩ) 90 80 60 40
Page 63 and 64:
3.3 A Low-Voltage Transimpedance Am
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
C 3 Φ1VB M 3 V B- =0.7V M 7 Figure
Page 75 and 76:
Page 77 and 78:
3.4 SUMMARY 3.4 Summary 71 In this
Page 79 and 80:
3.4 Summary 73 Y. Nakagome et al.,
Page 81 and 82: 4.1 Introduction 75 back topology o
Page 83 and 84: 4.2 Circuit Analysis Using Driving-
Page 91 and 92: 4.3 DPI/SFG: Combining DPI Analysis
Page 93 and 94: 4.4 Determining Port Impedances 87
Page 95 and 96: v i R in v o R out 4.4 Determining
Page 97 and 98: id » ro and 1 ⁄ rid « Av ⁄ ro
Page 103 and 104: Z b r e g m 4.5 Analyzing Transisto
Page 105 and 106: 4.5 Analyzing Transistor Circuits 9
Page 107 and 108: Figure 4.25 SFG for the source foll
Page 115 and 116: 5.1 Analysis of the Low-Voltage Tra
Page 117 and 118: 5.1 Analysis of the Low-Voltage Tra
Page 119 and 120: 5.2 DEVELOPING AN ANALYTIC CIRCUIT
Page 121 and 122: Z in 5.2 Developing an Analytic Cir
Page 123 and 124: 5.2 Developing an Analytic Circuit
Page 125 and 126: I n1 : i in I n2 -I n1 i scin ( sCi
Page 129 and 130: I nRf : 5.2 Developing an Analytic
Page 131: DC transimpedance gain: Pole locati
Page 135 and 136: Pole frequencies(MHz) 500 450 400 3
Page 137 and 138: Optimizing Sensitivity 5.2 Developi
Page 141 and 142: Transimpedance Volts dB (lin) Gain
Page 143 and 144: CHAPTER 6 Implementation and Experi
Page 145 and 146: 6.1 A 1V Optical Receiver Front-End
Page 149 and 150: 6.1.2 Experimental Results 6.1 A 1V
Page 151 and 152: Gain(dB) 0 −1 −2 −3 −4 −5
Page 159 and 160: Clock signal of voltage doubler Eye
Page 161 and 162: 6.2 Variable-Gain Transimpedance Am
Page 163 and 164: 6.2.2 Experimental Results 6.2 Vari
Page 165 and 166: 6.3 Summary and State-of-the-Art Co
Page 167 and 168: Reference Outputs Technology Supply
Page 169 and 170: CHAPTER 7 Conclusions 7.1 SUMMARY A
Page 171 and 172: 7.2 Future Work 165 The significanc
Page 173 and 174: 7.2 Future Work 167 supply and subs
Page 175 and 176: v s i ti that part of the SFG for Q
Page 177 and 178: Thus, P1 ′ = b = 500Ω ∆1 ′
Page 179 and 180: itive representation of circuit dyn
Page 181 and 182: Bipolar Transistor i scb Z b v b b
show all

CMOS Optical Preamplifier Design Using Graphical Circuit Analysis

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?