Tag Archives: RF

Polar vs Cartesian RF Modulator Efficiency

By Poojan Wagh | Published: March 21, 2009
I’ve been fielding quite a few questions lately about polar modulation. Indeed, polar modulators are theoretically more efficient. However, this does not need to be the case. I will highlight (technically, self-promote) a Cartesian scheme that can produce an RF signal as efficiently as a polar modulator—with fewer implementation issues.
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Supply voltage, current, RF impedance, and CMOS scaling

By Poojan Wagh | Published: November 11, 2008
Consider the circuit below: Let’s say that you’ve designed the circuit with a supply voltage (VDD) of 2.4 V. It’s performing very well. You meet exactly the specified linearity and noise requirements, and are within the desired current limits. The power dissipated across the PMOS and NMOS devices which dictate SNR are: PMOS: IDP×VDSATP = 10 mA×0.6 [...]
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Fundamentals of Analog/RF design: Noise, Signal, Power

By Poojan Wagh | Published: November 5, 2008
Analog design does not scale the way digital design does. Namely, as process shrinks, one does not immediately benefit by having reduced power consumption for the same performance. I will show in this post the main constraint involved in analog/RF design: that to maintain a given SNR, a certain amount of power must be consumed [...]
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Definition of IP3

By Poojan Wagh | Published: August 28, 2008
This point, where |A×x| = |c×X3| is the third-order intercept point.
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