14-09-2012, 05:16 PM
06-11-2012, 11:17 AM
Analog Circuits
Analog Circuits.ppt (Size: 1.46 MB / Downloads: 30) Introduction Two reasons of the differential amplifier suited for IC fabrication: IC fabrication is capable of providing matched devices. Utilizing more components than single-ended amplifier: Differential circuits are much less sensitive to noise and interference. Differential configuration enable us to bias the amplifier and to couple amplifier stages without the need for bypass and coupling capacitors. Operation with a Common –Mode Input Voltage Symmetry circuit. Common-mode voltage. Current I divides equally between two transistors. The difference between two drains is zero. The differential pair rejects the common-mode input signals. Operation with a Differential Input Voltage Differential input voltage. Response to the differential input signal. The current I can be steered from one transistor to the other by varying the differential input voltage in the range: When differential input voltage is very small, the differential output voltage is proportional to it, and the gain is high. Basic Operation The differential pair with a common-mode input signal vCM. Two transistors are matched. Current source with infinite output resistance. Current I divide equally between two transistors. The difference in voltage between the two collector is zero. The differential pair rejects the common-mode input signal as long as two transistors remain in active region. |
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