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HMC993LP5E

v00.0911

RF AUTOMATIC GAIN CONTROLLER

(RF-AGC), 700 - 3000 MHz

Figure 1b: The HMC993LP5E’s VGA configuration with 2 attenuators, 1900 MHz tune.

VGA Operation

The HMC993LP5E’s VGA core can be configured with one or two variable attenuators followed by two fixed gain

amplifiers for different control ranges as shown in Figure 1a and Figure 1b (basic connections are not shown). Note

that the link between VCTRL and DETOUT pins must be broken for correct VGA Operation. The VCTRL pin should be

used to set the attenuation of the HMC993LP5E.

Gain Control Interface VCTRL

The VCTRL pin is the gain control pin common to both of HMC993LP5E’s identical voltage variable attenuators. The

VCTRL gain control voltage ranges between 1V and 4V. A VCTRL control voltage of 1V provides the lowest attenuation,

while 4V provides the highest attenuation.

Figure 2 represents the VGA operation of HMC993LP5E with two attenuators and two amplifiers for different gain control

voltages applied to the VCTRL pin. The output power increases linearly with the input power until the power saturation is

reached when the VCTRL voltage is constant. The useable input power range of such a system is limited by the satura-

tion level of the final stage amplifier. So the input power level required for power saturation and the dynamic range of the

HMC993LP5E’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 HMC993LP5E’s VGA with 2 attenuators is 21.5 dB at 1900 MHz. The input power required

for 1 dB compression point at the output is given by: Pin1dB = Pout1dB – Gain (dB) + 1 = 25 – 21.5 + 1 = 4.5 dB.

When VCTRL=2V, the gain of the HMC993LP5E’s VGA with 2 attenuators is 11.7 dB at 1900 MHz. The input power

required for 1 dB compression point at the output is given by: Pin1dB = Pout1dB – Gain (dB) + 1 = 25 – 11.7 + 1 = 14.3

dB.