Timeline for Differential Pairs and GND
Current License: CC BY-SA 4.0
8 events
| when toggle format | what | by | license | comment | |
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| Jan 6, 2020 at 21:27 | comment | added | Circuit fantasist | @ peufeu, You are right about the connection between the differential stage and next stage. Designers alternate transistors: if the input stage is implemented with p-n-p, the next stage is implemented with n-p-n transistors and vice versa. Thus the output of each stage is alternatively referenced to the negative and positive rails. | |
| Jan 6, 2020 at 19:41 | comment | added | Circuit fantasist | @ Kinka-Byo, When the lower end of the current source is connected to a negative power supply, the MOSFET sources can go down below zero so the gates are at zero input voltage. This means there is no need of some biasing from the side of gates since the transistors are biased from the side of sources. Only the gates should be somehow connected to ground - either through the input single-ended sources or through additional resistors (see the picture below). | |
| Jan 6, 2020 at 18:28 | comment | added | bobflux | @Kinka-Byo With positive and negative supplies the circuit can process and output both positive and negative voltage, and reference is really 0V. | |
| Jan 6, 2020 at 18:25 | comment | added | Kinka-Byo | Regarding the power supply, which is the advantage of choosing 2 supplies? | |
| Jan 6, 2020 at 18:16 | comment | added | bobflux | Indeed... but I've never seen a circuit where the next stage is referenced to GND, usually it's a VAS stage like this or another diff pair, or a folded cascode, all referenced to positive supply... | |
| Jan 6, 2020 at 18:13 | history | edited | bobflux | CC BY-SA 4.0 |
added 4 characters in body
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| Jan 6, 2020 at 18:09 | comment | added | Circuit fantasist | I have a note about "the output is Voltage on resistor 'R', so it is referenced to Vdd. Your schematic shows it referenced to ground, which is incorrect." Really, the voltage drop across R is the true voltage output of the stage. R acts as a current-to-voltage converter that converts the output collector current to output voltage and this voltage is tied to Vcc. But usually the input of the next stage is tied to ground; so we use the complementary voltage Vcc - VR as an output instead the original VR. We can use VR directly if the next stage is with the opposite P-channel transistors. | |
| Jan 6, 2020 at 16:15 | history | answered | bobflux | CC BY-SA 4.0 |
