3D Time-of-flight distance measurement with custom - Universität ...

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DEMODULATION PIXELS IN CMOS/CCD 109 and the necessary correction of the measured data appear to be impractical. Summarizing, the 4-tap pixel approach is only partly suited to range measurements, since, for modulation frequencies higher than 1 MHz, it suffers from transfer inhomogeneities between the single transfer gates. 5.1.3 1-tap lock-in pixel Both pixel concepts introduced so far suffer from a low optical fill factor. In-pixel storage always occupies space, in proportion to the number of sampling points to be stored. The multitap approach only works up to 1MHz modulation frequency (realized with 4 storage sites) because the demodulation process happens in the extended area of a CCD line with design-rule-limited long CCD gates. The four-tap lock-in pixel accesses the photogate with four different transfer gates, resulting in an inhomogeneous response of the four sampling points. All of these limitations can be traced back to the requirement of realizing four independent in-pixel storage sites. The one-tap lock-in pixel ignores this requirement and offers only one storage site but attempts to maximize the fill factor. Therefore, the sampling points have to be stored externally. Figure 5.6 shows the layout and a cross-sectional view (including the potential distribution in the semiconductor) of the 1-tap pixel. The left and the right light sensitive photogates (PGL and PGR) have a length of 6 µm, the middle photogate a length of 2.5 µm; the pixel width is 21 µm. Each pixel also includes a reset transistor, a source follower transistor (buffer amplifier) and the select transistor (cascode with source follower). This leads to a pixel size of 65 µm by 21 µm and an optical fill factor of more than 20%. The pixel’s working principle is illustrated in Figure 5.7: By applying proper gate voltages to the photogates, the potential gradient in the semiconductor can be influenced (c.f. Chapter 3). If the control voltages of the photogates are changed synchronously with the modulated incoming light, optically generated charge carriers can either be integrated (if they belong to the sampling interval) or they are dumped to the dump diffusion (if they do not belong to the sampling interval). This process can be repeated until the integration gate (IG) has accumulated a sufficiently large signal. The addition or accumulation of single electrons under the integration gate is essentially noise free. This sampling mechanism is shown in Figure 5.7 (a), whereas (b) describes the
110 CHAPTER 5 same process in terms of a correlation of the optically generated input signal s(t) with the sampling signal f(t+τ). The fast channeling of the optical input signal and distribution either to the dump diffusion or to the integration gate can be interpreted as a multiplication of the electrooptical signal s(t) with the sampling function f(t+τ). With the integration under the IG this corresponds to a correlation process. See also Section 2.2.1. potential metal wire contact n+ diffusion poly 2 poly 1 light opening Dimensions: photogate: 21x14.5 µm 2 , pixel: 21x65 µm 2 , aspect ratio: 1:3, fill factor: 22%. sense IG diff. OUTG PGM PGL PGR dump diff. Figure 5.6 One-tap lock-in pixel: Pixel layout and cross sectional view of the CCD part. (IG: integration gate; PGL/ PGM/ PGR: left/ middle/ right photogate). The tradeoff of this mode of operation is that the overall integration time is longer than for the previously introduced pixels and a certain amount of light is wasted because the incoming light is either integrated or rejected. In both previous approaches, the dead-time of one sampling point was always the active-time of some other sampling point, thus all incoming modulated light was used for evaluation during the demodulation period. This drawback can be partly compensated by choosing half the modulation period as integration time for each
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3D Time-of-flight distance measurem
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To my parents
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Meinen Eltern
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II 4. Power budget and resolution l
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Abstract Since we are living in a t
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centimeter accuracy. With the singl
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X Eine elegantere Methode zur Entfe
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INTRODUCTION 1 1. Introduction One
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INTRODUCTION 3 light source observe
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INTRODUCTION 5 Propagation time, ho
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INTRODUCTION 7 Chapter 3 gives a sh
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OPTICAL TOF RANGE MEASUREMENT 9 2.
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OPTICAL TOF RANGE MEASUREMENT 13 pr
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OPTICAL TOF RANGE MEASUREMENT 15 hi
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OPTICAL TOF RANGE MEASUREMENT 17 Pu
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OPTICAL TOF RANGE MEASUREMENT 19 Ad
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OPTICAL TOF RANGE MEASUREMENT 21 pr
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OPTICAL TOF RANGE MEASUREMENT 23 wh
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OPTICAL TOF RANGE MEASUREMENT 25 δ
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OPTICAL TOF RANGE MEASUREMENT 27 c(
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OPTICAL TOF RANGE MEASUREMENT 29 A
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OPTICAL TOF RANGE MEASUREMENT 31 ph
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OPTICAL TOF RANGE MEASUREMENT 33 Ts
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OPTICAL TOF RANGE MEASUREMENT 35 f1
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OPTICAL TOF RANGE MEASUREMENT 37 an
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OPTICAL TOF RANGE MEASUREMENT 39 in
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OPTICAL TOF RANGE MEASUREMENT 41 Ss
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OPTICAL TOF RANGE MEASUREMENT 43 Fr
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OPTICAL TOF RANGE MEASUREMENT 45 1
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50 CHAPTER 3 the smearing effect, r
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52 CHAPTER 3 3.1 Silicon properties
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54 CHAPTER 3 (a) Figure 3.3 Optical
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56 CHAPTER 3 Quantum efficiency in
Page 75 and 76: 58 CHAPTER 3 The different operatio
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Page 79 and 80: 62 CHAPTER 3 Very special processes
Page 81 and 82: 64 CHAPTER 3 1 kT Dn = ⋅ vth ⋅
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Page 85 and 86: 68 CHAPTER 3 difference of only 1 V
Page 87 and 88: 70 CHAPTER 3 Flicker noise is cause
Page 89 and 90: 72 CHAPTER 3 A s = sf ⋅ q C ⎡ V
Page 91 and 92: 74 CHAPTER 3 amount of the charge p
Page 93 and 94: 76 CHAPTER 3 substrate (Equation 3.
Page 95 and 96: 78 CHAPTER 3 charge carriers the CT
Page 97 and 98: 80 CHAPTER 3 without causing short
Page 99 and 100: 82 CHAPTER 3 Over an address decode
Page 101 and 102: 84 CHAPTER 3 Orbit’s 2.0µm CMOS/
Page 103 and 104: 86 CHAPTER 4 Figure 4.1 P lens Lamb
Page 105 and 106: 88 CHAPTER 4 Required optical power
Page 107 and 108: 90 CHAPTER 4 4.2 Noise limitation o
Page 109 and 110: 92 CHAPTER 4 number of pseudo-backg
Page 111 and 112: 94 CHAPTER 4 Cmod = 1 QE(λ) = 0.65
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Page 116 and 117: DEMODULATION PIXELS IN CMOS/CCD 99
Page 168 and 169: IMAGING TOF RANGE CAMERAS 151 6. Im
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IMAGING TOF RANGE CAMERAS 159 6.2 2
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IMAGING TOF RANGE CAMERAS 161 n+ di
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IMAGING TOF RANGE CAMERAS 163 pixel
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IMAGING TOF RANGE CAMERAS 165 Power
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IMAGING TOF RANGE CAMERAS 167 Delay
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IMAGING TOF RANGE CAMERAS 169 6.3 3
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IMAGING TOF RANGE CAMERAS 171 Gate
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IMAGING TOF RANGE CAMERAS 173 Bound
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IMAGING TOF RANGE CAMERAS 175 Figur
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IMAGING TOF RANGE CAMERAS 177 Final
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IMAGING TOF RANGE CAMERAS 179 #5 #6
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SUMMARY AND PERSPECTIVE 181 7. Summ
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SUMMARY AND PERSPECTIVE 183 into th
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SUMMARY AND PERSPECTIVE 185 or phas
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188 CHAPTER 8 8.2 Typical parameter
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190 CHAPTER 8 Spectral luminous int
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192 CHAPTER 8 MCD03S: Conditions SC
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194 CHAPTER 8 MCD06S: Measurement c
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196 [BRK] Brockhaus, “Naturwissen
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198 [KAI] I. Kaisto, et al., “Opt
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200 [SP1] T. Spirig et al., “The
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ACKNOWLEDGMENTS 203 Acknowledgments
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206 Publication list 1. R. Lange, P
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