For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, 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

16

HMC992LP5E

v03.1013

IF AUTOMATIC GAIN CONTROLLER

(IF-AGC), 50 - 800 MHz

Figure 2: Pout vs. Pin at 100 MHz, 1 attenuator

-40

-30

-20

-10

0

10

20

-70

-60

-50

-40

-30

-20

-10

0

10

VCTRL=1 V

VCTRL=2 V

VCTRL=3 V

VCTRL=4 V

INPUT POWER (dBm)

HMC992LP5E’s VGA is defined by the value of the gain control voltage applied to the VCTRL pin. Refer to the Figure 2

for the useable input power range at different VCTRL levels.

When VCTRL=1V, the gain of HMC992LP5E’s VGA with 2 attenuators is 39 dB at 100 MHz. The input power required for

1 dB compression point at the output is given by: Pin1dB = Pout1dB – Gain (dB) = 18 – 39 = -21 dB.

When VCTRL=2V, the gain of the HMC992LP5E’s VGA with 2 attenuators is 25 dB at 100 MHz. The input power required

for 1 dB compression point at the output is given by: Pin1dB = Pout1dB – Gain (dB) = 18 – 25 = -7 dB.

Therefore, increasing the VCTRL pin voltage reduces the gain of the HMC992LP5E’s VGA and increases input power

level required for power saturation. When the input signal is weak, the attenuation level of the variable attenuators

should be reduced. When the input signal is large; the attenuation level of the variable attenuators should be increased

to achieve a constant output level.

The gain control performance of the HMC992LP5E at 300 MHz is shown in Figures 3a and 3b. The HMC992LP5E

provides 24 dB of gain control range with a maximum gain of 41.2 dB when it is configured in 1 attenuator + 2 ampli-

fiers mode, and similarly a 48 dB of gain control range with a maximum gain of 39 dB of gain when it is configured in 2

attenuators + 2 amplifiers mode. The HMC992LP5E’s VGA has a very flat linear-in-dB gain control characteristic with a

slope of -18.2 dB/V for the 2 attenuator configuration and -9.1 dB/V for the 1 attenuator configuration. The log-linearity

error of the HMC992LP5 VGA is typically less than ± 1dB over the entire gain control range as shown in Figure 3a and

Figure 3b. The relation between the gain of HMC992LP5E’s VGA and VCTRL pin voltage can be approximated as given

in Equation (1).

Gain (dB) = 52.5 – 9.1 x VCTRL with one attenuator

Equation (1a)

Gain (dB) = 61.0 – 18.2 x VCTRL with two attenuators

Equation (1b)

Figure 3a: Gain & Gain Conformance Error vs. VCTRL at 300 MHz, 1 attenuator + 2 amplifiers configuration.

15

20

25

30

35

40

45

1

1.5

2

2.5

3

3.5

4

Ideal

Gain

-3

-2

-1

0

1

2

3

Error

VCTRL (V)

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.

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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