MPhil thesis of Lo Chi Wa - Department of Electronic & Computer ...

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Phase mismatchTypical designThis proposeddesignTimeFig. 80 Phase error with time of coupled LC oscillators without common source connection and withconnectionDesign considerationsIn addition to the LC oscillator, the size of the four coupling transistors and their biasneed to be designed. The four transistors form a 4-stage-ring-oscillator-like frame forthe two LC oscillators to be put inside as shown in Fig. 81. The frame tries to maintainthe quadrature-phase relationship between the two LC oscillators, while the twoimperfectly matched LC oscillators try to oscillate at different frequencies and break thequadrature-phase relationship. At the same time, the LC oscillators maintain the purityof the frequency while the ring oscillator gives a poor phase noise. Thus, it is a tradeoffbetween the quadrature-phase maintenance and the phase-noise performance. The ratioof transistor sizes and biases of the coupling transistors (the ring oscillator) to thenegative feedback transistors in LC oscillator determines whether the whole oscillator iscloser to being either a ring oscillator with poor phase noise but good phase matching ora LC oscillator with poor phase matching but good phase noise. The tradeoff should bemade based on the mismatches of the LC tanks, the quadrature phase, and phase noise84
equirements. Fortunately, by connecting the two bias current sources together, thequadrature-phase relationship becomes stronger and the coupling transistors can besmaller to reduce the noise and increase the tuning range of the oscillator. Similar to thetwo negative gm cells, the common source nodes of coupling transistors are alsoconnected together to increase the gain and improve the matchings. However, lesssignificant effect is observed due to the smaller size and bias.Layout considerationsFig. 81 Different views of the coupled-LC oscillatorsGood matching of the transistors is important to maintain a good quadrature outputswith amplitude and phase matchings. Instead of putting two identical oscillatorstogether, they have to be considered and laid out as a whole. Instead of pairs oftransistors, groups of four transistors have to be matched by layout techniques, such asinterleaving, common centroid and rotational symmetry. A special floorplan techniqueis used to match two oscillators. For good IQ matching, every transistor is split into twoto match with the transistors of 90-degree phase lag and 90-degree phase lead as shown85
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A 1.5-V 900-Mhz Monolithic CMOSFast
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A 1.5-V 900-Mhz Monolithic CMOS Fas
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Table of ContentsPageAcknowledgment
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Testing setup......................
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List of FiguresPageFig. 1 Block dia
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Fig. 76 Amplitudes and currents of
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Chapter 1 IntroductionBackgroundWir
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applications because it can provide
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existing monolithic frequency synth
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the receiver frequency band is from
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out-of-bandin-bandout-of-band0dBmin
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Based on the maximum interference,
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carrierdBcspur∆fFig. 8 Frequency
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Spurs requirement (dBc)Frequency of
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The frequency diversity can be perf
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Chapter 3 System DesignPhase-locked
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coarse tuning can be provided by th
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array is now possible. Moreover, th
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performance of the synthesizer 9 .
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signalquantizationnoisea) f b)signa
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esolution. The loop bandwidth is 80
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the output value between 0 and 0.5,
Page 45 and 46: The coupled-LC oscillators can be v
Page 47 and 48: 890MHzf25MHz243KHz865MHzFig. 23 Tun
Page 49 and 50: onoffCwellClinearCwellClinearCwellC
Page 51 and 52: spirals of similar sizes is around
Page 53 and 54: in Fig. 27a and Fig. 27b, the same
Page 55 and 56: conductance (Gm) and the reciprocal
Page 57 and 58: −19⎛ 900M⎞0.0259×1.6×10 ×
Page 59 and 60: GdoVinFig. 32 Gdo of the proposed L
Page 61 and 62: RzCzIcpCpR4C4a)IcpCzR4B.IcpCpRpC4b)
Page 63 and 64: Usually, capacitors in the filter o
Page 65 and 66: RVinFig. 38 Resistance of NMOS resi
Page 67 and 68: feedback path to prevent the proble
Page 69 and 70: 890MHz25MHz865MHzfA+∆A
Page 71 and 72: High-speed multi-modulus dividerThe
Page 73 and 74: CLKQBQDDBFig. 50 Schematic diagram
Page 75 and 76: ANDgateABclkclkclkclkQBFig. 54 Sche
Page 77 and 78: f o/2 /2,3 /2,3 /2 /2f div/4Combina
Page 79 and 80: next stage, as shown in the Fig. 59
Page 81 and 82: co10bDclkclkFig. 60 Schematic of th
Page 83 and 84: (1-Z -1 ) 23bDQBclkZ -1 (1-Z -1 )2b
Page 85 and 86: X 16clkDclkQBDclkQBFig. 66 Schemati
Page 87 and 88: ~90 oa) b) c)Fig. 68 Different meth
Page 89 and 90: (dotted line). As the oscillation c
Page 91 and 92: In practice, it is not desirable to
Page 93 and 94: and decrease in amplitude mismatch
Page 95: Current interactionThe two oscillat
Page 99 and 100: LC oscillators are put apart to red
Page 101 and 102: Gain mismatch (in %)Two oscillators
Page 103 and 104: equals to1 . By doubling the height
Page 105 and 106: 30 is obtained. It is because the s
Page 107 and 108: The spiral inductor is designed and
Page 109 and 110: oscillators (shown in the upper and
Page 111 and 112: Synthesizer LayoutThe layout and th
Page 113 and 114: Die LayoutFig. 98 shows the die pho
Page 115 and 116: Testing setupThe testing setup show
Page 117 and 118: Resistance (ohms)Freq (Hz)Fig. 101
Page 119 and 120: Resistance (ohms)Freq (Hz)Fig. 105
Page 121 and 122: VaractorFig. 109 shows the testing
Page 123 and 124: Table 5 Summary of parameters of va
Page 125 and 126: Table 6 Summary of N-well substrate
Page 127 and 128: Fig. 120 Quality factor of the swit
Page 129 and 130: The decrease in quality factor is d
Page 131 and 132: Fig. 126 Schematic diagram of the p
Page 133 and 134: Output frequency(MHz)Number of swit
Page 135 and 136: Gain (MHz/V)Tuning voltage (v)Fig.
Page 137 and 138: on the process variation. Therefore
Page 139 and 140: voltage (Vos = Rp x Ios) appeared.
Page 141 and 142: Although the spurs are quite large,
Page 143 and 144: GMSK signals with 0.3 BT and a bit
Page 145 and 146: Power spectral density (dB)(b)(a)(c
Page 147 and 148:
Summary of performanceA summary of
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Table 10 Comparison of performances
Page 151 and 152:
As the voltage-controlled oscillato
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Bibliography1 Thomas H. Lee, The De
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MPhil thesis of Lo Chi Wa - Department of Electronic & Computer ...

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