07-01-2025: Design of biasing

Lecture: EE4109-13

Location: Pulse Hall 7 (33.A2.200)

Time: 15:45 - 17:30

Biasing design considerations

Biasing proceeds in two steps:

1. Design of the biasing with ideal voltage and current sources; this comprises the following actions:

   1. Biasing sources will be added to the transistors: four per transistor, as discussed in Chapter 3

   2. The power supply is added to the circuit

   3. Amplifier ports that should be referenced to the power supply are connected to one terminal of the power supply (called: signal reference)

   4. Bias current sources are redirected via the power supply, such that they can be impelemnted with passive elements

   5. The number of voltage sources in series with the signal path is minimized, by choosing N or P devices, by replacing CS with CD stages, or by changing the drain-source operating voltages

2. Design of the bias current and voltage sources

   1. A sufficiently accurate, stable and low-noise voltage or current reference (can be the power supply) is used as starting point for the design

   2. All other sources are derived from this reference, and their design procedure equals that of an amplifier. The most important characteristics are:

      1. Current source: current to be deliverd, accuracy, temperature stability, voltage handling capability, associated noise current, small-signal impedance

      2. Voltage source: voltage to be deliverd, accuracy, temperature stability, current handling capability, associated noise voltage, small-signal impedance

Guided group exersise

We will discuss the biasing of the single-stage and the dual stage solution of the hearing loop receive amplifier.

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