For price, delivery and to place orders: Hittite Microwave Corporation, 20 Alpha Road, Chelmsford, MA 01824

Phone: 978-250-3343

Fax: 978-250-3373

Order On-line at www.hittite.com

Application Support: Phone: 978-250-3343 or apps@hittite.com

11

11 - 20

HMC909LP4E

v02.0511

RMS POWER DETECTOR

SINGLE-ENDED, DC - 5.8 GHz

Standby Mode

the eNX can be used to force the power detector into a low-power standby mode. As eNX is deactivated, power is

restored to all of the circuits. there is no memory of previous conditions. coming-out of stand-by, internal integration

and coFs capacitors will require recharging, so if large scI values have been chosen, the wake-up time will be

lengthened.

Modulation Performance – Crest factor performance

the HMc909LP4e can detect modulated signals with very high crest factors accurately.

For example, up to 2.7 GHz, a modulated rF signal with a crest factor of 15 dB can be detected with 0.3 dB error.

RMSOUT Error vs.

Crest Factor over Frequency

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

3

4

5

6

7

8

9

10

11

12

13

14

15

900 MHz error from CW (-22 dBm)

1900 MHz error from CW (-22 dBm)

2700 MHz error from CW (-22 dBm)

3900 MHz error from CW (-22 dBm)

CREST FACTOR (dB)

System Calibration

Due to part-to-part variations in log-slope and log-intercept, a system-level calibration is recommended to satisfy

absolute accuracy requirements. when performing this calibration, choose at least two test points: near the top end

and bottom-end of the measurement range. It is best to measure the calibration points in the regions (of frequency

and amplitude) where accuracy is most important. Derive the log-slope and log-intercept, and store them in non-

volatile memory.

For example if the following two calibration points were measured at 2.2 GHz:

with rMsoUt = 1.81V at Pin= -20 dBm,

and rMsoUt = 1.03V at Pin= -40 dBm

slope calibration constant = scc

SCC = (-40+20)/(1.03-1.81) = 25.64 dB/V

intercept calibration constant = Icc

ICC = Pin – SCC*RMSOUT = -20 - 25.64 * 1.81 = -66.41 dBm

Now performing a power measurement at -30 dBm:

rMsoUt measures 1.40V

[Measured Pin] = [Measured RMSOUT]*SCC + ICC

[Measured Pin] = 1.40 * 25.64 - 66.41 = -30.51 dBm

An error of only 0.51 dB

Factory system calibration measurements should be made using an input signal representative of the application. If

the power detector will operate over a wide range of frequencies, choose a central frequency for calibration.

Information furnished by Analog Devices is believed to be accurate and reliable. However, no

responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other

rights of third parties that may result from its use. Specifications subject to change without notice. No

license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

Trademarks and registered trademarks are the property of their respective owners.

For price, delivery, and to place orders: Analog Devices, Inc.,

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106

Phone: 781-329-4700 • Order online at www.analog.com

Application Support: Phone: 1-800-ANALOG-D