Compare BJT with FET
FET
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BJT
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It is unipolar device i.e. current in the device is carried either by electrons or holes
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It is bipolar device i.e. current in the device is carried either by both electrons & holes
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It is a voltage controlled device i.e. voltage at the gate (or drain) terminal controls amount of current flowing through the device.
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It is a current controlled device i.e. the base current controls the amount of collector current.
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Its input resistance is very high & is of order of several megaohms.
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Its input resistance is very low compared to FET.
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It has a negative temperature co-efficient at high current levels. It means that current decreases as temperature increases.
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It has a positive temperature coefficient at high current levels. It means that current increases as temperature increases.
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It is less noisy.
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It is comparatively noisier.
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It has relatively lower gain bandwidth product as compared to BJT.
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It has relatively higher gain bandwidth product as compared to FET.
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It is simpler to fabricate as IC & occupies less space on chip compared to BJT.
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It is comparatively difficult to fabricate on IC & occupies more space on chip compared to FET.
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It is relatively immune to radiation.
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It is susceptible to radiation
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It does not suffer from minority- carrier storage effects & therefore has higher switching speeds & cut-off frequencies.
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It suffers from minority- carrier storage effects & therefore has lower switching speeds & cut-off frequencies.
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