Single-Stage Integrated- Circuit Amplifiers 1

Table 6.3 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0601.jpg Figure 6.1 The intrinsic gain of the MOSFET versus bias current ID. Outside the subthreshold region, this is a plot of for the case: mnCox = 20 mA/V2, V9A = 20 V/mm, L = 2 mm, and W = 20 mm. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0602a.jpg Figure 6.2 Frequency response of a CS amplifier loaded with a capacitance CL and fed with an ideal voltage source. It is assumed that the transistor is operating at frequencies much lower than fT, and thus the internal capacitances are not taken into account. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0603.jpg Figure 6.3 Increasing ID or W/L increases the bandwidth of a MOSFET amplifier loaded by a constant capacitance CL. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0604.jpg Figure 6.4 Circuit for a basic MOSFET constant-current source. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0605.jpg Figure 6.5 Basic MOSFET current mirror. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0606.jpg Figure 6.6 Output characteristic of the current source in Fig. 6.4 and the current mirror of Fig. 6.5 for the case Q2 is matched to Q1. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0607.jpg Figure 6.7 A current-steering circuit. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0608.jpg Figure 6.8 The basic BJT current mirror. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0609.jpg Figure 6.9 Analysis of the current mirror taking into account the finite b of the BJTs. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0610.jpg Figure 6.10 A simple BJT current source. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0611.jpg Figure 6.11 Generation of a number of constant currents of various magnitudes. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_e0608.jpg Figure E6.8 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0612.jpg Figure 6.12 Frequency response of a direct-coupled (dc) amplifier. Observe that the gain does not fall off at low frequencies, and the midband gain AM extends down to zero frequency. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0613.jpg Figure 6.13 Normalized high-frequency response of the amplifier in Example 6.5. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0614a.jpg Figure 6.14 Circuits for Example 6.6: (a) high-frequency equivalent circuit of a MOSFET amplifier; (b) the equivalent circuit at midband frequencies; (c) circuit for determining the resistance seen by Cgs; and (d) circuit for determining the resistance seen by Cgd. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0615.jpg Figure 6.15 The Miller equivalent circuit. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0616a.jpg Figure 6.16 Circuit for Example 6.7. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_e0613.jpg Figure E6.13 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0617a.jpg Figure 6.17 (a) Active-loaded common-source amplifier. (b) Small-signal analysis of the amplifier in (a), performed both directly on the circuit diagram and using the small-signal model explicitly. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0618a.jpg Figure 6.18 The CMOS common-source amplifier; (a) circuit; (b) i–v characteristic of the active-load Q2; (c) graphical construction to determine the transfer characteristic; and (d) transfer characteristic. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0619a.jpg Figure 6.19 (a) Active-loaded common-emitter amplifier. (b) Small-signal analysis of the amplifier in (a), performed both directly on the circuit and using the hybrid-p model explicitly. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0620.jpg Figure 6.20 High-frequency equivalent-circuit model of the common-source amplifier. For the common-emitter amplifier, the values of Vsig and Rsig are modified to include the effects of rp and rx; Cgs is replaced by Cp, Vgs by Vp, and Cgd by Cm. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0621.jpg Figure 6.21 Approximate equivalent circuit obtained by applying Miller’s theorem while neglecting CL and the load current component supplied by Cgd. This model works reasonably well when Rsig is large and the amplifier high-frequency response is dominated by the pole formed by Rsig and Cin. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0622a.jpg Figure 6.22 Application of the open-circuit time-constants method to the CS equivalent circuit of Fig. 6.20. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0623.jpg Figure 6.23 Analysis of the CS high-frequency equivalent circuit. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0624.jpg Figure 6.24 The CS circuit at s 5 sZ. The output voltage Vo 5 0, enabling us to determine sZ from a node equation at D. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0625a.jpg Figure 6.25 (a) High-frequency equivalent circuit of the common-emitter amplifier. (b) Equivalent circuit obtained after the Thévenin theorem is employed to simplify the resistive circuit at the input. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0626a.jpg Figure 6.26 (a) High-frequency equivalent circuit of a CS amplifier fed with a signal source having a very low (effectively zero) resistance. (b) The circuit with Vsig reduced to zero. (c) Bode plot for the gain of the circuit in (a). Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0627a.jpg Figure 6.27 (a) Active-loaded common-gate amplifier. (b) MOSFET equivalent circuit for the CG case in which the body and gate terminals are connected to ground. (c) Small-signal analysis performed directly on the circuit diagram with the T model of (b) used implicitly. (d) Operation with the output open-circuited. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0628a.jpg Figure 6.28 (a) The output resistance Ro is found by setting vi 5 0. (b) The output resistance Rout is obtained by setting vsig 5 0. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0629.jpg Figure 6.29 The impedance transformation property of the CG configuration. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0630.jpg Figure 6.30 Equivalent circuit of the CG amplifier illustrating its application as a current buffer. Rin and Rout are given in Fig. 6.29, and Gis 5 Avo (Rs/Rout) . 1. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0631a.jpg Figure 6.31 (a) The common-gate amplifier with the transistor internal capacitances shown. A load capacitance CL is also included. (b) Equivalent circuit for the case in which ro is neglected. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0632a.jpg Figure 6.32 Circuits for determining Rgs and Rgd. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0633a.jpg Figure 6.33 (a) Active-loaded common-base amplifier. (b) Small-signal analysis performed directly on the circuit diagram with the BJT T model used implicitly. (c) Small-signal analysis with the output open-circuited. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0634.jpg Figure 6.34 Analysis of the CB circuit to determine Rout. Observe that the current ix that enters the transistor must equal the sum of the two currents v/rp and v/Re that leave the transistor, that is; ix 5 v/rp 1 v/Re. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0635.jpg Figure 6.35 Input and output resistances of the CB amplifier. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0636a.jpg Figure 6.36 (a) The MOS cascode amplifier. (b) The circuit prepared for small-signal analysis with various input and output resistances indicated. (c) The cascode with the output open-circuited. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0637ab.jpg Figure 6.37 (a and b) Two equivalent circuits for the output of the cascode amplifier. Either circuit can be used to determine the gain Av 5 vo/vi, which is equal to Gv because Rin 5 ¥ and thus vi 5 vsig. (c) Equivalent circuit for determining the voltage gain of the CS stage, Q1. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0638.jpg Figure 6.38 The cascode circuit with the various transistor capacitances indicated. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0639abc.jpg Figure 6.39 Effect of cascoding on gain and bandwidth in the case Rsig 5 0. Cascoding can increase the dc gain by the factor A0 while keeping the unity-gain frequency constant. Note that to achieve the high gain, the load resistance must be increased by the factor A0. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0640a.jpg Figure 6.40 (a) The BJT cascode amplifier. (b) The circuit prepared for small-signal analysis with various input and output resistances indicated. Note that rx is neglected. (c) The cascode with the output open-circuited. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0641a.jpg Figure 6.41 (a) Equivalent circuit for the cascode amplifier in terms of the open-circuit voltage gain Avo 5 –bA0. (b) Equivalent circuit in terms of the overall short-circuit transconductance Gm . gm. (c) Equivalent circuit for determining the gain of the CE stage, Q1. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0642.jpg Figure 6.42 Determining the frequency response of the BJT cascode amplifier. Note that in addition to the BJT capacitances Cp and Cm, the capacitance between the collector and the substrate Ccs for each transistor are also included. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0643.jpg Figure 6.43 A cascode current-source. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0644.jpg Figure 6.44 Double cascoding. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0645.jpg Figure 6.45 The folded cascode. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0646a.jpg Figure 6.46 BiCMOS cascodes. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0647a.jpg Figure 6.47 (a) A CS amplifier with a source-degeneration resistance Rs. (b) Circuit for small-signal analysis. (c) Circuit with the output open to determine Avo. (d) Output equivalent circuit. (e) Another output equivalent circuit in terms of Gm. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0648a.jpg Figure 6.48 (a) The CS amplifier circuit, with a source resistance Rs, prepared for frequency-response analysis. (b) Determining the resistance Rgd seen by the capacitance Cgd. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0649a.jpg Figure 6.49 A CE amplifier with emitter degeneration: (a) circuit; (b) analysis to determine Rin; and (c) analysis to determine Avo. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0650a.jpg Figure 6.50 (a) An IC source follower. (b) Small-signal equivalent-circuit model of the source follower. (c) A simplified version of the equivalent circuit. (d) Determining the output resistance of the source follower. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0651a.jpg Figure 6.51 Analysis of the high-frequency response of the source follower: (a) Equivalent circuit; (b) simplified equivalent circuit; and (c) determining the resistance Rgs seen by Cgs. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0652a.jpg Figure 6.52 (a) Emitter follower. (b) High-frequency equivalent circuit. (c) Simplified equivalent circuit. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0653a.jpg Figure 6.53 (a) CD–CS amplifier. (b) CC–CE amplifier. (c) CD–CE amplifier. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0654a.jpg Figure 6.54 Circuits for Example 6.13: (a) The CC–CE circuit prepared for low-frequency small-signal analysis; (b) the circuit at high frequencies, with Vsig set to zero to enable determination of the open-circuit time constants; and (c) a CE amplifier for comparison. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0655a.jpg Figure 6.55 (a) The Darlington configuration; (b) voltage follower using the Darlington configuration; and (c) the Darlington follower with a bias current I applied to Q1 to ensure that its b remains high. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0656a.jpg Figure 6.56 (a) A CC–CB amplifier. (b) Another version of the CC–CB circuit with Q2 implemented using a pnp transistor. (c) The MOSFET version of the circuit in (a). Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0657a.jpg Figure 6.57 (a) Equivalent circuit for the amplifier in Fig. 6.56(a). (b) Simplified equivalent circuit. Note that the equivalent circuits in (a) and (b) also apply to the circuit shown in Fig. 6.56(b). In addition, they can be easily adapted for the MOSFET circuit in Fig. 6.56(c), with 2rp eliminated, Cp replaced with Cgs, Cm replaced with Cgd, and Vp replaced with Vgs. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0658.jpg Figure 6.58 A cascode MOS current mirror. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0659.jpg Figure 6.59 A current mirror with base-current compensation. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0660a.jpg Figure 6.60 The Wilson bipolar current mirror: (a) circuit showing analysis to determine the current transfer ratio; and (b) determining the output resistance. Note that the current ix that enters Q3 must equal the sum of the currents that leave it, 2i. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0661a.jpg Figure 6.61 The Wilson MOS mirror: (a) circuit; (b) analysis to determine output resistance; and (c) modified circuit. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0662.jpg Figure 6.62 The Widlar current source. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0663a.jpg Figure 6.63 Circuits for Example 6.14. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0664.jpg Figure 6.64 Capture schematic of the CS amplifier in Example 6.15. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0665.jpg Figure 6.65 Transistor equivalency. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0665a.jpg Figure 6.66 (a) Voltage transfer characteristic of the CS amplifier in Example 6.15. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0665b.jpg Figure 6.66 (Continued) (b) Expanded view of the transfer characteristic in the high-gain region. Also shown are the transfer characteristics where process variations cause the width of transistor M1 to change by +15% and –15% from its nominal value of W1 = 12.5 mm. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0667.jpg Figure 6.67 Capture schematic of the CS amplifier in Example 6.16. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0668.jpg Figure 6.68 Frequency response of (a) the CS amplifier and (b) the folded-cascode amplifier in Example 6.16, with Rsig = 100 W and Rsig = 1 mW. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_0669.jpg Figure 6.69 Capture schematic of the folded-cascode amplifier in Example 6.16. Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06009a.jpg Figure P6.9 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06025.jpg Figure P6.25 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06026.jpg Figure P6.26 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06028.jpg Figure P6.28 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06033.jpg Figure P6.33 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06034.jpg Figure P6.34 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06035.jpg Figure P6.35 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06037.jpg Figure P6.37 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06046.jpg Figure P6.46 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06054.jpg Figure P6.54 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06057.jpg Figure P6.57 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06061.jpg Figure P6.61 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06063.jpg Figure P6.63 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06065.jpg Figure P6.65 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06072.jpg Figure P6.72 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06073.jpg Figure P6.73 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06075.jpg Figure P6.75 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06076a.jpg Figure P6.76 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06083.jpg Figure P6.83 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06084.jpg Figure P6.84 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06085.jpg Figure P6.85 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06093.jpg Figure P6.93 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06096.jpg Figure P6.96 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06098.jpg Figure P6.98 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06099a.jpg Figure P6.99 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06107a.jpg Figure P6.107 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06122.jpg Figure P6.121 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06123.jpg Figure P6.122 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06124.jpg Figure P6.123 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06125.jpg Figure P6.124 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06128a.jpg Figure P6.127 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06131.jpg Figure P6.130 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06136.jpg Figure P6.134 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06145.jpg Figure P6.143 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06146.jpg Figure P6.144 Microelectronic Circuits - Fifth Edition Sedra/Smith

sedr42021_p06147.jpg Figure P6.145 Microelectronic Circuits - Fifth Edition Sedra/Smith