噪声作业 –SCUTEEE

噪声作业

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Among the output noise and the input-referred noise, which one is more popular to be used in the circuit simulation? Why?

Devices are often specified with input-referred noise, because, with an amplifier for example, the output noise will depend on gain so is not constant.

7.12 Assuming that $λ = γ = 0$ , calculate the input-referred thermal noise voltage of each circuit in Fig. 7.75. For part (a), assume that $g_{m 3, 4} = 0.5 g_{m 5, 6}$ .

Figure 7.75 解：(a)

\begin{aligned} | A_{v} | & = g_{m 1, 2} R_{out} \\ \overset{―}{V_{n, out}^{2}} & = 4 k T γ (2 g_{m 1, 2} + 2 g_{m 3, 4} + 2 g_{m 5, 6}) R_{out}^{2} \\ = 4 k T γ (2 g_{m 1, 2} + 3 g_{m 5, 6}) R_{out}^{2} \\ \overset{―}{V_{n, in}^{2}} & = 4 k T γ (\frac{2}{g_{m 1, 2}} + \frac{3 g_{m 5, 6}}{g_{m 1, 2}^{2}}) \end{aligned}

(b) The input-referred noise voltage of the five-transistor OTA is the same as that of the fully-differential circuit.

\begin{aligned} G_{m} & = g_{m 1, 2} \\ \overset{―}{I_{n, out}^{2}} & = 4 k T γ (g_{m 1} + g_{m 2} + g_{m 3} + g_{m 4}) \\ \overset{―}{V_{n, in}^{2}} & = \frac{\overset{―}{I_{n, out}^{2}}}{G_{m}^{2}} = 4 k T γ (\frac{2}{g_{m 1, 2}} + \frac{2 g_{m 3, 4}}{g_{m 1, 2}^{2}}) \end{aligned}

噪声