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 - 19

HMC909LP4E

v02.0511

RMS POWER DETECTOR

SINGLE-ENDED, DC - 5.8 GHz

example: the logarithmic intercept can also be adjusted by choosing appropriate rFBK, rsHUNt, and rset

values.

setting rFBK = 4.7KΩ, rsHUNt =2.2KΩ, and rset = 24KΩ results in an optimized slope of:

Optimized Slope = ß * log_slope = 1.67 * 36.9 mV / dB

optimized slope = 62 mV / dB

Optimized Intercept = log_intercept –(RFBK/RSET)*VBLINE

Optimized Intercept = log_intercept - 0.196 * VBLINE

Intercept Adjustment

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

-70

-60

-50

-40

-30

-20

-10

0

VBLINE = -3.2 V

VBLINE = -1.6 V

VBLINE = -0.8 V

VBLINE =

0 V

VBLINE = +0.8 V

VBLINE = +1.6 V

VBLINE = +3.2 V

INPUT POWER (dBm)

Rset = 24 Kohm

Rfbk = 4.7 Kohm

Rshunt = 2.2 Kohm

DC Offset Compensation Loop

Internal Dc offsets, which are input signal dependant, require continuous cancellation. offset cancellation is a critical

function needed for maintenance of measurement accuracy and sensitivity. the Dc offset cancellation loop performs

this function, and its response is largely defined by the capacitance (COFS) connected between COFSA, COFSB

pins.

coFs sets the loop bandwidth of the Dc offset compensations. Higher coFs values are required for measuring

lower rF frequencies. the optimal loop bandwidth setting will allow internal offsets to be cancelled at a minimally

acceptable speed.

Dc offset cancellation Loop ≈

Bandwidth , Hz

For example: loop bandwidth for Dc cancellation with coFs = 1nF, bandwidth is ~62 kHz

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