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Re: plz can any one tell me ?expain Low-power design techniq
Hi, there is a very promising and actual technique for low power design (for voltages less tha 1 volt) called "log-domain design".
There was already a topic to this subject and I have responded to it on May 8 2008.
Here, I repeat the main items again:
1.) The motivation of this principle is connected with low power and low supply voltage requirements (Vss=1 Volt or even lower) of modern mobile communication units.
2.) The circuits (mostly in integrated form) consists of capacitors as well as BJTs and MOSFETs only. All transistors work either as U-I resp. I-U converters (with log characteristics) or as current sources.
3.) Therefore, transistors are biased with very small currents (mikro-amps) well below their saturation region, where the exponential law applies. This is true also to MOSFETS which are working in the subthreshold region (weak inversion).
4.) As a result – supply voltages in the order of 1 Volt and smaller are possible.
5.) Because input-output linearity is required, a symmetrical process of compressing/ expanding (companding) is applied.
6.) This principle leads to specific transistor arrangements which have been named by Barry Gilbert as “translinear” circuits.
Finally, if you are interested I can provide some good and introductory papers to the principle of log domain signal processing.
LvW
Hi, there is a very promising and actual technique for low power design (for voltages less tha 1 volt) called "log-domain design".
There was already a topic to this subject and I have responded to it on May 8 2008.
Here, I repeat the main items again:
1.) The motivation of this principle is connected with low power and low supply voltage requirements (Vss=1 Volt or even lower) of modern mobile communication units.
2.) The circuits (mostly in integrated form) consists of capacitors as well as BJTs and MOSFETs only. All transistors work either as U-I resp. I-U converters (with log characteristics) or as current sources.
3.) Therefore, transistors are biased with very small currents (mikro-amps) well below their saturation region, where the exponential law applies. This is true also to MOSFETS which are working in the subthreshold region (weak inversion).
4.) As a result – supply voltages in the order of 1 Volt and smaller are possible.
5.) Because input-output linearity is required, a symmetrical process of compressing/ expanding (companding) is applied.
6.) This principle leads to specific transistor arrangements which have been named by Barry Gilbert as “translinear” circuits.
Finally, if you are interested I can provide some good and introductory papers to the principle of log domain signal processing.
LvW
How does this handle process variation? usually when using micro amps the circuits are extremely sensitive to process variation. which means DFM is a problem.
Re: plz can any one tell me ?expain Low-power design techniq
Hi, I must confess - as an analog "guru" - I have assumed that the topic was directed to pure analog circuitry with low voltage requirements. Maybe, therefore, that my former post was not appropriate.
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