Audio Engineering

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Audio Amplifi ers John Linsley Hood Solid-state device technologies, which are available to the amplifi er designer, fall, broad ...

284 Chapter 9 very high purity single crystal silicon. A few devices are still made in germanium, mainly for replacement purpose ...

Audio Amplifi ers 285 Ic hfe Ib Figure 9.1 : BJT nonlinearity. hfe Frequency Figure 9.2 : Decrease in hfe with frequency. shown ...

286 Chapter 9 is a grossly nonlinear amplifying device, even if some input (positive in the case of an NPN device) DC bias volta ...

Audio Amplifi ers 287 Figure 9.4 : Biasing circuits. R 2 R 1 Vb Vcc C 1 Q 1 0V Output Input (a) R 2 R 1 Vcc C 1 Q 1 0V Output ...

288 Chapter 9 R 4 will then determine the emitter and collector currents, and the operating conditions so provided will hold goo ...

Audio Amplifi ers 289 Q 2 will be relatively low because of the high effective source resistance seen by the Q 2 base. A similar ...

290 Chapter 9 The cascode layout is also used very widely as a voltage amplifi er stage, using a circuit arrangement of the kind ...

Audio Amplifi ers 291 amplifi er where there is a high impedance between cathode and ground—it is less good from the point of vi ...

292 Chapter 9 (a) Vcc Output Vref R 2 Q 1 Q 2 R 1 0V 0V Input Figure 9.8 : Long-tailed pair layouts. (b) Vref 2 Vref 1 Output  ...

Audio Amplifi ers 293 sit at a quiescent potential about 0.6 V more negative than that of the base, and this will follow, quite ...

294 Chapter 9 forward voltage drop, whereas the layout of Figure 9.11 will have two, giving a combined quiescent voltage offset ...

Audio Amplifi ers 295 in a BJT is the phenomenon known as thermal runaway. This can happen because the potential barrier of a P- ...

296 Chapter 9 characteristic, which is, in the case of an N-channel JFET, very similar to that of a triode valve, as shown in cu ...

Audio Amplifi ers 297 pentode valve, which the junction FET greatly resembles in its operational characteristics, the simplest w ...

298 Chapter 9 layout, coupled with the high stage gain of the BJT. The source potential of the JFET (Q 2 ) will be determined by ...

Audio Amplifi ers 299 arrangement is to allow a JFET amplifi er stage to operate at a much higher rail voltage than would be all ...

300 Chapter 9 rather worse noise fi gure than an equivalent JFET, but, on the plus side, they have rather more closely controlle ...

Audio Amplifi ers 301 techniques in a lateral MOSFET will be too long to allow a low channel “ on ” resistance. For high current ...