Radio Geek


Parallel Resonant Circuit

A parallel resonant RLC circuit is shown in Figure 1. The input admittance of a parallel R-L-C circuit is given by, (1)   By definition, at resonant frequnecy inductive and capacitive susceptances are equal in magnitude and opposite in phase. Therefore they cancel each other. (2)   Quality factor(Q) of […]


References – Phase Locked Loops

Phase-Locked Loops for High-Frequency Receivers and Transmitters, Mike Curtin &; Paul O’Brien, Analog Devices Part-1 |┬áPart-2 |┬áPart-3 Practical Tips for Phase Locked Loop Design, Dennis Fischette Fractional/Integer-N PLL Basics, Curtis Barrett, Texas Intruments PLL Performance, Simulation and Design Handbook 4th Edition Dean Banerjee, Natioanal Semiconductor A Fully Integrated Fractional-N Frequency […]


Cadence lock files 2 comments

If cadence is not properly exited or crashed, it results in edit locks on cadence files that were open at the time of exiting. These lock files have extension ‘.cdslck’. After restarting cadence, we have to remove edit locks to continue editing on those files. We have two options to […]


LTE Carrier Frequency and EARFCN

EARFCN stands for E-UTRA Absolute Radio Frequency Channel Number.In LTE, the carrier frequency in the uplink and downlink is designated by EARFCN, which ranges between 0-65535. EARFCN uniquely identify the LTE band and carrier frequency. For example Band-1 and Band-4 can have same Rx frequency 2110-2170 MHz,  but their EARFCN […]


Analog/RF IC Design Research Groups

Some Analog/RF IC design research groups around the world: Research in RFIC Design, Meyer/Niknejad Group, University of California, Berkeley. Research in Analog IC Design, Paul Gray/Robert Meyer Group,University of California, Berkeley. Communication Circuits Laboratory (CCL) , Razavi, University of California, Los Angeles. High Speed Electronics Laboratory , M.C. Frank Chang, […]


Carrier Triple Beat Test

Triple beat test is employed to mimic the cross-modulation distortion scenario and validate the performance in 3G and 4G/LTE devices. In Triple Beat test two tones and at Tx frequency and another tone at Rx frequency produces, intermod components at . If the two Tx tones are very close, then […]


Third order Intercept Point (IP3)

Thrid order intercept point(IP3) is a used to quantify weak non-linearity in an amplifier or RF system. It is an interpolated point where the fundamental component power curve meets the third order intermod(IMD3) component power curve. Consider a nonlinear amplifier whose input-output characteristic is represented by a 3rd order polynomial […]


Maximum Power Transfer

The power transfer from a source to it’s load is maximum when their respective impedance are complex conjugate of each other. Let and The power delivered to load is given by (1)   The condition for maximum power transfer is Therefore, and Under this condition, power delivered to load is […]


dBm Calculator

dBm is the power ratio of measured power referenced to 1 milliwatt (mW) in decibels (dB).     (1)   A change in power ratio by a factor of 10 is a 10 dB change. A change in power ratio by a factor of 2 is approximately a 3 dB […]