Analog Devices just announced the release of the latest version of their
applet for calculating cascaded RF component parameters. It takes typical input values for
up to 15 stages and returns typical cascaded values at the output. As I do with any such program,
I compared its results with those of my
RF Cascade Workbook (RFCW) spreadsheet. The numbers agree as expected since both use pretty
much the same set of well-established textbook formulas.
One difference in the two programs is that
appears to use the standard IP3 (3rd-order intercept point) cascade formula for calculating
P1dB (1 dB compression point)*, whereas
RFCW uses Psat (saturated power) instead since the P1dB formula is only an approximation
of widely varying nonlinear response and might lead to a false sense of security. RFCW's Psat
calculated values simply test what the output power level for a device would be if the gain
were always linear, and sets a warning flag if it exceeds the specified Psat value. Doing
so always errs on the side of caution. As long as the user is aware of the method used, he
can proceed with confidence with either option.
If you don't like using a spreadsheet and only need the information hard-coded into the
application, then ADISimRF is a good choice, but honestly, the flexibility of a spreadsheet
is probably worth reconsidering your preferences.
* I could not find anywhere that the ADI folks stipulate how P1dB
is calculated, but entering the device P1dB values into the IP3 fields results in the exact
same output value. Here is a write-up I did on
approximating cascaded P1dB
with the IP3 formula and why it is not always valid.
ADISimRF v1.7 Example Screen
RF Cascade Workbook 2005 Example Screen
Here is the full text of the press release:
Feb. 25, 2013 13:00 UTC
New Version of Analog Devices’ Simulation Tool Significantly Eases Development
of RF Systems
NORWOOD, Mass.--(BUSINESS WIRE)-- Analog Devices, Inc. (ADI) today announced the release
of a new version of its popular ADIsimRF™
design tool. The free design tool is the software accompaniment to ADI's complete portfolio
of RF-to-digital functional blocks, allowing engineers to model RF signal chains using devices
from across ADI's RF IC and data converter portfolio.
ADIsimRF Version 1.7 adds a number
of new device models along with enhanced support for inter-stage mismatch calculations. The
design tool provides calculations for the most important parameters within an RF signal chain,
including cascaded gain, noise figure, IP3, P1dB, and total power consumption. The ADIsimRF
design tool contains embedded data from many of ADI's RF ICs and data converters, which designers
can easily access using pull-down menus to assist in component selection.
Download ADIsimRF design tool:
View video demonstration of ADIsimRF:
View ADI's broad portfolio of RF ICs: http://www.analog.com/rf
View ADI's leading portfolio of data converters:
Browse ADI's RF design tools: http://www.analog.com/rftools
ADIsimRF Version 1.7 Key Features:
The new version of the ADIsimRF design tool includes significant enhancements to inter-stage
mismatch calculations. One of the tool’s unique capabilities as an RF signal chain calculator
is its ability to calculate scalar mismatch loss that results when two adjacent devices
have different output and input impedances. In ADIsimRF Version 1.7, device models for many
non-50 Ohm devices such as I/Q Demodulators, VGAs and ADC Drivers have been tweaked in order
to take full advantage of the tool’s ability to factor the effect of inter-stage mismatch
into cascaded IP3, P1dB, gain and noise figure calculations. The new version also adds device
models for ADI’s latest RF ICs, including the ADRF6755 I/Q Modulator and the ADL5324, ADL5321
and ADL5320 Driver Amplifiers.
About Analog Devices
Innovation, performance, and excellence are the cultural pillars on which Analog Devices
has built one of the longest standing, highest growth companies within the technology sector.
Acknowledged industry-wide as the world leader in data conversion and signal conditioning
technology, Analog Devices serves over 60,000 customers, representing virtually all types
of electronic equipment. Analog Devices is headquartered in Norwood, Massachusetts, with design
and manufacturing facilities throughout the world. Analog Devices is included in the S&P
Posted February 25, 2013