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COLORADO STATE UNIVERSITY
ECE 332: ELECTRONIC PRINCIPLES II
HOMEWORK 6
1. Sketch the p-channel counterpart of the current-source circuit in the figure shown below.
Note that the circuit should more appropriately be called a current sink, the corresponding
PMOS circuit is a current source. Let 𝑉𝐷𝐷 = 1.8 𝑉, |𝑉𝑡 | = 0.5 𝑉, 𝑄1 and 𝑄2 be matched, and
𝜇𝑝 𝐶𝑜𝑥 = 100𝜇𝐴/𝑉 2 . Find the device 𝑊/𝐿 ratios and the value of the resistor that sets the
value of 𝐼𝑅𝐸𝐹 so that a nominally 80𝜇𝐴 output current is obtained. The current source is
required to operate for 𝑉𝑜 as high as 1.6V. Neglect channel-length modulation.
2. For the current-steering circuit shown in the figure below, find 𝐼𝑂 in terms of 𝐼𝑅𝐸𝐹 and device
𝑊/𝐿 ratios of four transistors.
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3. The current-steering circuit shown in the figure below is fabricated in a CMOS technology for
which 𝜇𝑛 𝐶𝑜𝑥 = 200𝜇𝐴/𝑉 2 , 𝜇𝑝 𝐶𝑜𝑥 = 80𝜇𝐴/𝑉 2 , 𝑉𝑡𝑛 = 0.6 𝑉, 𝑉𝑡𝑝 = −0.6 𝑉, 𝑉′𝐴𝑛 = 10 𝑉/𝜇𝑚,
|𝑉′𝐴𝑝 | = 12 𝑉/𝜇𝑚. If all devices have 𝐿 = 0.8𝜇𝑚, design the circuit so that 𝐼𝑅𝐸𝐹 = 20 𝜇𝐴,
𝐼2 = 100 𝜇𝐴, 𝐼3 = 𝐼4 = 20 𝜇𝐴, and 𝐼5 = 50 𝜇𝐴. Use the minimum possible device widths
needed to achieve proper operation of the current source 𝑄2 for voltages at its drain as high
as +1.3V and proper operation of the current sink 𝑄5 with voltages at its drain as low as 1.3V. Specify the widths of all devices and the value R. Find the output resistance of the
current source 𝑄2 and the output resistance of the current sink 𝑄5 .
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