LMH2110_15 Datasheet, PDF (22/36 Pages) Texas Instruments – LMH2110 8-GHz Logarithmic RMS Power Detector with 45-dB Dynamic Range

LMH2110
SNWS022D – JANUARY 2010 – REVISED JUNE 2015
Typical Applications (continued)
8.2.1.1 Design Requirements
Some of the design requirements for this logarithmic RMS power detector include:
Table 1. Design Parameters
DESIGN PARAMETER
Supply voltage
RF input frequency (unmodulated continuous wave)
Minimum power level
Maximum power level
Maximum output voltage
EXAMPLE VALUE
2.7 V
1900 MHz
–36 dBm
0 dBm
1.5 V
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8.2.1.2 Detailed Design Procedure
8.2.1.2.1 Specifying Detector Performance
The performance of the LMH2110 can be expressed by a variety of parameters.
8.2.1.2.1.1 Dynamic Range
The LMH2110 is designed to have a predictable and accurate response over a certain input power range. This is
called the dynamic range (DR) of a detector. For determining the dynamic range a couple of different criteria can
be used. The most commonly used ones are:
• Log conformance error, E_LC
• Variation over temperature error, E_VOT
• 1-dB step error, E_{1 dB}
• 10-dB step error, E_{10 dB}
• Variation due to modulation, E_MOD
The specified dynamic range is the range in which the specified error metric is within a predefined window. See
Log Conformance Error, Variation Over Temperature Error, Variation Over Temperature Error, 1-dB Step Error,
10-dB Step Error, and Variation Due to Modulation for an explanation of these errors.
8.2.1.2.1.2 Log Conformance Error
The LMH2110 implements a logarithmic function. In order to describe how close the transfer is to an ideal
logarithmic function the log conformance error is used. To calculate the log conformance error the detector
transfer function is modeled as a linear-in-dB relationship between the input power and the output voltage.
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