PA1

ANTENNA

RFIN1

LMV232

RF

INPUT

OUT

R1

6.2 k:

RFIN2

PA2

RF

INPUT

FB

BS

SD

VDD

GND

A3

B3

C1

B1

A1

C3

C2

A2

R3

50:

C1

1.5 nF

COUPLER

COUPLER

TO BASEBAND

R2

50:

LMV232

www.ti.com

SNWS017C – DECEMBER 2004 – REVISED MARCH 2013

Figure 21. Typical Application

The detection curves of Figure 22 show the detector response to RF input power. To show the complete dynamic

range on a logarithmic scale, the pedestal voltage (VPEDESTAL) is subtracted from the output. The pedestal

voltage is defined as the output voltage in the absence of an RF input signal (at 25°C). The best-fit ideal mean

square response is represented by the fitted curve in Figure 22. The input referred error of the detection curves

with respect to this best-fit mean square response is determined as follows:

•

Determine the best-fit mean square response.

•

Determine the output referred error between the actual detector response and the ideal mean square

response.

•

Translate the output referred error to an input referred error.

Figure 22. Detection Curve

The best-fit linear curve is obtained from the detector response by means of linear regression. The output

referred error is calculated with the formula:

ErrordBV = 20*log[ (VOUT-VPEDESTAL)/(KDET*PIN) ]

Where,

Conversion gain of the ideal fitted curve KDET is in V/mW and the RF input power PIN in mW.

To translate this output referred error (in dB) to an input referred error, it has to be divided by a factor of 2. This

is due to the mean square characteristic of the device. The response of a mean square detector changes by 2

dB for every dB change of the input power. Figure 23 depicts the resulting curve.

Copyright © 2004–2013, Texas Instruments Incorporated

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